WO2025188723A1

WO2025188723A1 - Hybridized advanced additive manufacturing

Info

Publication number: WO2025188723A1
Application number: PCT/US2025/018297
Authority: WO
Inventors: Cody Alexander SHELTRA; Zane DUSTIN; Andrew SCHANCK; Roberto Antonio LOPEZ-ANIDO; William Glenn DAVIDS
Original assignee: University of Maine System
Current assignee: University of Maine System
Priority date: 2024-03-04
Filing date: 2025-03-04
Publication date: 2025-09-12
Anticipated expiration: 2026-09-04
Also published as: WO2025188723A8

Abstract

The present disclosure provides, inter alia, hybridized advanced additive manufacturing methods including prefabricating a workpiece that includes a melt layer disposed on at least one bonding surface, thereby forming a prefabricated portion of the workpiece; disposing the prefabricated portion of the workpiece onto a build platform within an additive manufacturing build area of an additive manufacturing system; activating the bonding surface using a light source; and printing, layer-by-layer, on top of the bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with the prefabricated portion of the workpiece.

Description

HYBRIDIZED ADVANCED ADDITIVE MANUFACTURING

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No. 63/561,281 filed March 04, 2024, the disclosure of which is incorporated by reference herein in its entirety.

BACKGROUND

[0002] The recent resurgence in additive manufacturing (AM) is characterized by a shift towards employing AM for production, customization, and flexible manufacturing, particularly in sectors requiring on-demand production. The industry's growth is propelled by a diverse range of materials, including polymers, metals, and ceramics, with a growing focus on sustainability. This focus includes the development of novel, recyclable polymers that align with global environmental sustainability trends. However, many modalities of AM faces unique challenges related to layer-by-layer deposition, which limits its widespread adoption beyond niche applications. These challenges include 1) the need to use extra material during printing for structural support (i.e., support structures), 2) limitations in the possible geometries that can be 3D printed (i.e., additively manufactured), and 3) limitations in the diversity of materials that are capable of being 3D printed, among various other challenges.

SUMMARY

[0003] Presented herein are hybridized advanced additive manufacturing (HAAM) systems and methodologies. The HAAM systems and methodologies include using additive manufacturing in connection with at least one other type of manufacturing. For example, a workpiece may be prefabricated using a first manufacturing process, and then brought within a manufacturing system where a 3D printing process may occur on the prefabricated workpiece, thereby resulting in a finished workpiece that includes both a prefabricated portion and a 3D-printed (or additively manufactured) portion. The prefabricated and 3D- printed portions may be composed of substantially similar materials, and may be joined via melt bonding. The resulting finish workpiece therefore, may include a smooth transition between the prefabricated portion and the 3D-printed such that the two portions are unitary, continuous, and/or monolithic with each other. In some embodiments, the prefabricated workpiece may include a melt layer that may be heated to help facilitate melt bonding with the 3D-printed layers, which may be heated to approximately the same temperature as the melt layer as part of the 3D-printing process.

[0004] In one aspect, the present disclosure is direct to a method including: prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece including a melt layer disposed on at least one bonding surface of the prefabricated workpiece (e.g., a top surface of a workpiece); disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system; applying heat to the at least one bonding surface and/or the melt layer; printing, layer-by- layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece including the prefabricated workpiece.

[0005] In some embodiments, printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system includes forming a transition layer between the prefabricated portion of the workpiece and the 3D-printed portion of the workpiece.

[0006] In some embodiments, the transition layer includes a thickness in a range from about 1pm to about 5pm.

[0007] In some embodiments, the method includes determining (e.g., predicting) (e.g., prior to layer-by-layer printing) (e.g., by a processor of a computer (e.g., using FEA)) thermal distortion(s) of the printed portion of the workpiece and the prefabricated portion of the workpiece induced during the layer-by-layer printing of the printed portion of the workpiece.

[0008] In some embodiments, the determination of the thermal distortion(s) includes: conducting a heat transfer analysis of the workpiece and the prefabricated portion of the workpiece at a plurality of time points (e.g., at least two, at least three, at least four or more) during the layer-by-layer printing process; and determining a plurality of nodal temperatures. [0009] In some embodiments, the method includes performing a structural analysis of the workpiece and the prefabricated portion of the workpiece at the plurality of time points based on, at least, the plurality of nodal temperature.

[0010] In some embodiments, the method includes mitigating (e.g., by heating, cooling, modifying a tool path, etc.) the determined thermal distortions.

[0011] In some embodiments, the thermal distortion(s) includes thermal strain and/or thermal stress.

[0012] In some embodiments, method includes cooling portions of prefabricated workpiece adjacent to and/or disposed beneath the melt layer.

[0013] In some embodiments, the method includes determining (e.g., predicting) (e.g., prior to layer-by-layer printing) (e.g., by a processor of a computer (e.g., using finite element analysis (FEA))) mechanical distortion(s) of the printed portion of the workpiece and the prefabricated portion of the workpiece induced during the layer-by-layer printing of the printed portion of the workpiece.

[0014] In some embodiments, the determination of the mechanical distortion(s) includes conducting an analysis of the workpiece and the prefabricated portion of the workpiece at a plurality of time points (e.g., at least two, at least three, at least four or more) during the layer-by-layer printing process.

[0015] In some embodiments, the method includes performing a structural analysis of the workpiece and the prefabricated portion of the workpiece at the plurality of time points.

[0016] In some embodiments, the method includes mitigating (e.g., by heating, cooling, modifying a tool path, etc.) the determined mechanical distortions.

[0017] In some embodiments, the method includes prefabricating the prefabricated workpiece using one or more of the following techniques: investment casting, injection molding, forging, composite manufacturing, continuous forming (e.g., via a continuous forming machine (CFM)), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, and machining.

[0018] In some embodiments, the method includes prefabricating the prefabricated portion using one or more of the following techniques: composite manufacturing, polymer matrix composites (PMC) manufacturing, metal matrix composites (MMC) manufacturing, and carbon matrix composites (CMC) manufacturing.

[0019] In some embodiments, the melt layer includes a thickness of about 200pm or less (e.g., 175pm or less, 150pm or less, e.g., from about 10pm to about 200pm, from about 25pm to about 150pm, and/or from about 50pm to about 100 pm).

[0020] In some embodiments, the method includes heating the prefabricated workpiece (e.g., a surface of the prefabricated workpiece) to a temperature from about 150- °C to about 314°C.

[0021] In some embodiments, the method includes heating the prefabricated workpiece to about 400°C or less (e.g., 314°C or less, 150°C or less).

[0022] In some embodiments, the prefabricated workpiece is substantially at room temperature.

[0023] In some embodiments, the additive manufacturing system includes a nozzle for deposition of the printing material and heating the printing material to a temperature about 400°C or less (e.g., 257°C or less).

[0024] In some embodiments, the additive manufacturing system includes a nozzle for deposition of the printing material and heating the printing material to a temperature from about 85°C to about 257°C.

[0025] In some embodiments, the prefabricated workpiece includes one or more thermoplastics.

[0026] In some embodiments, the prefabricated workpiece includes polyethylene terephthalate glycolpolycarbonate (PETG), polyethylene (e.g., high-density polyethylene (HDPE), e.g., low-density polyethylene (LDPE)), polypropylene (PP), polyetheretherketone, polyaryletherketone (e.g., low melt polyaryletherketone), polyamide (e.g., nylon 6, nylon 6 6, nylon 6 12, nylon 4,6 nylon 12, polyamide 12 (PA12), etc.), acrylonitrile butadiene styrene (ABS), polylactic acid (PLA), polyvinylchloride (PVC), polycarbonate (PC), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), poly(methyl methacrylate) (PMMA), polyetherimide (PEI), polybenzimidazole (PBI), or any combination thereof. [0027] In some embodiments, the prefabricated workpiece and/or the printing material includes glass fibers (e.g., E-glass), carbon fibers, aramid fibers, basalt fibers, organic fibers (e.g., hemp fibers, e.g., wood-derived fibers), or any combination thereof. [0028] In some embodiments, the method includes placing (e.g., using an automated system) a reinforcing component within the printed portion of the workpiece during layer- by-layer printing.

[0029] In some embodiments, the method includes use of a multi -axis 3D printer to deposit the printing material around the reinforcing component.

[0030] In another aspect, the present disclosure is directed to a hybrid workpiece including: a prefabricated portion; and a 3D printed portion, wherein the prefabricated portion is melt-bonded to the 3D printed portion, thereby forming the hybrid workpiece as a unitary structure, wherein the prefabricated portion includes a composite structure including at least one fiber embedded within a matrix, and wherein the 3D printed portion is formed via a continuous, layer-by-layer build process.

[0031] In some embodiments, the 3D printed portion includes one or more reinforcing components.

[0032] In some embodiments, both the prefabricated portion and the 3D printed portion includes materials from the same class of materials as that of a melt layer disposed between the portions.

[0033] In some embodiments, the prefabricated portion is formed using one or more of the following techniques: investment casting, injection molding, forging, composite manufacturing, continuous forming (e.g., via a continuous forming machine (CFM)), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, and machining.

[0034] In some embodiments, the at least one fiber embedded within a matrix is a glass fiber (e.g., E-glass), a carbon fiber, an aramid fiber, a basalt fiber, or an organic fiber (e.g., hemp fibers, e.g., wood-derived fibers).

[0035] In some embodiments, the matrix includes polyethylene terephthalate glycolpolycarbonate (PETG), polyethylene (e.g., high-density polyethylene (HDPE), e.g., low-density polyethylene (LDPE)), polypropylene (PP), polyetheretherketone, polyaryletherketone (e.g., low melt polyaryletherketone), polyamide (e.g., nylon 6, nylon 6 6, nylon 6 12, nylon 4,6 nylon 12, polyamide 12 (PA12), etc.), acrylonitrile butadiene styrene (ABS), polylactic acid (PA), polyvinylchloride (PVC), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), poly(methyl methacrylate) (PMMA), polyetherimide (PEI), polybenzimidazole (PBI), or any combination thereof.

[0036] In some embodiments, the melt layer includes a thickness of about 200pm or less (e.g., 175pm or less, 150pm or less, e.g., from about 10pm to about 200pm, from about 25pm to about 150pm, from about 50pm to about 100 pm).

[0037] In another aspect, the present disclosure is directed to a method (e.g., of identifying thermal and/or mechanical distortions in a composite 3D printed part) including: determining (e.g., by a processor of a computer (e.g., using FEA)) thermal and/or mechanical distortion(s) (e.g., thermal stresses and/or strains, mechanical stresses and/or strains) of a hybrid workpiece including a prefabricated portion and a 3D printed portion created by layer-by-layer deposition of a material (e.g., a heated material) using an additive manufacturing system; identifying (e.g., by the processor) thermal and/or mechanical distortion(s) of the workpiece induced by the layer-by-layer deposition of the material (e.g., the heated material), wherein the thermal and/or mechanical distortion(s) are beyond a predetermined threshold level; modifying (e.g., by the processor) at least one layer-by-layer deposition parameter to reduce the thermal and/or mechanical distortion(s) induced on the prefabricated workpiece.

[0038] In some embodiments, the material is a heated material.

[0039] In some embodiments, determining the thermal distortion(s) is based on, at least, one or more parameters for layer-by-layer deposition of the heated material by an additive manufacturing system.

[0040] In some embodiments, the method includes identifying a plurality of temperatures of the hybrid workpiece (e.g., using an infrared camera, predictively generating the temperatures) at a plurality of timepoints and locations within the hybrid workpiece during the layer-by-layer deposition of the heated material onto the hybrid workpiece.

[0041] In some embodiments, the method includes identifying the thermal distortion(s) using a structural analysis based on, at least, the shape of the hybrid workpiece and the plurality of temperatures. [0042] In some embodiments, the at least one deposition parameters includes at least one of the following deposition parameters: a temperature of the prefabricated workpiece, a path of a tool used in layer-by-layer deposition, a hybrid workpiece cooling rate, and a speed of layer-by-layer deposition.

[0043] In some embodiments, printing, layer by layer, includes raising a temperature of the printing material.

[0044] In some embodiments, printing, layer by layer, includes raising a temperature of the printing material to within a melting temperature range of the printing material.

[0045] In some embodiments, material of the same class of materials includes material from one of the following classes of materials: polycarbonates (PC), polypropylenes (PP), polyethylene terephthalate glycolpolycarbonates (PETG), polyethylene materials (PE), acrylonitrile butadiene styrene (ABS) materials, polylactic acids, polyvinylchlorides (PVC), and polyamide 12.

[0046] In another aspect, the present disclosure is direct to method including: prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece including a melt layer disposed on at least one bonding surface of the prefabricated workpiece; disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system; heating the at least one bonding surface to glass transition temperature of the melt layer; printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece including the prefabricated workpiece.

[0047] In another aspect, the present disclosure is direct to a method including: prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece including a melt layer disposed on at least one bonding surface of the prefabricated workpiece (e.g., a top surface of a workpiece); disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system, wherein the prefabricated workpiece is partially supported; applying heat to the at least one bonding surface and/or the melt layer; printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece including the prefabricated workpiece.

[0048] In some embodiments, heating the at least one bonding surface (or substrate) includes heating the at least one bonding surface to a temperature in a range from about 50 degrees C to about 150 degrees C (for example, from about 80 degrees C to about 130 degrees C).

[0049] In some embodiments, printing, layer-by-layer, on top of at least one bonding surface includes doing so at a temperature in a range from about 190 degrees C to about 240 degrees C (for example, from about 200 degrees C to about 220 degrees C).

[0050] In some embodiments, the printed portion is or includes an overhang.

[0051] In another aspect, the present disclosure is direct to a hybrid workpiece including: a prefabricated portion; and a 3D printed portion, wherein the prefabricated portion is partially supported, wherein the prefabricated portion is melt-bonded to the 3D printed portion, thereby forming the hybrid workpiece as a unitary structure, wherein the prefabricated portion includes a composite structure including at least one fiber embedded within a matrix, and wherein the 3D printed portion is formed via a continuous, layer-by- layer build process.

[0052] In another aspect, the present disclosure is direct to a method (e.g., of light weighting a composite 3D printed part) including: determining (e.g., by a processor of a computer (e.g., using FEA)) thermal and/or mechanical distortion(s) of a hybrid workpiece including a prefabricated portion and a 3D printed portion created by layer-by-layer deposition of a material (e.g., a heated material) using an additive manufacturing system; reducing (e.g., by the processor) a cross-section of the hybrid workpiece; identifying (e.g., by the processor) thermal and/or mechanical distortion(s) of the workpiece induced by the layer-by-layer deposition of the material (e.g., the heated material); adjusting (e.g., by the processor) the cross-section of the hybrid workpiece to achieve a predetermined threshold level for the thermal and/or mechanical distortion(s).

[0053] Any two or more of the features described in this specification, including in this summary section, may be combined to form implementations not specifically or explicitly described in this specification. BRIEF DESCRIPTION OF THE DRAWING

[0054] Drawings are presented herein for illustration purposes, not for limitation. The foregoing and other objects, aspects, features, and advantages of the disclosure will become more apparent and may be better understood by referring to the following description taken in conjunction with the accompanying drawings, in which:

[0055] FIG. 1 shows a method of additive manufacturing, according to aspects of the present disclosure.

[0056] FIG. 2 shows a method of additive manufacturing, according to aspects of the present disclosure.

[0057] FIG. 3 shows illustrative embodiments of hybrid workpiece testing, according to aspects of the present disclosure.

[0058] FIGs. 4A-4C show multiple views of a continuous forming machine, according to aspects of the present disclosure.

[0059] FIGs. 5A-5D show illustrative embodiments of overprinting, according to aspects of the present disclosure.

[0060] FIG. 6 shows exemplary extrudate deposition-based systems for HAAM manufacturing, according to aspects of the present disclosure.

[0061] FIG. 7 shows an exemplary powder bed-based system for HAAM manufacturing, according to aspects of the present disclosure.

[0062] FIG. 8 shows an exemplary binder jet-based system for HAAM manufacturing, according to aspects of the present disclosure.

[0063] FIG. 9 shows an exemplary SLA-based system for HAAM manufacturing, according to illustrative embodiments of the present disclosure.

[0064] FIG. 10, panels A-C show the computed temperatures of a prefabricated workpiece before printing, according to aspects of the present disclosure.

[0065] FIG. 11 panels A-C show thermal distortions of HAAM produced parts, according to aspects of the present disclosure.

[0066] FIG. 12 illustrates a 3D-printed structure with exemplary overhang angles.

[0067] FIG. 13 illustrates a structure produced via HAAM, according to aspects of the present disclosure. [0068] FIG. 14 panels A-C show a die used for pultrusion (A), a pultruded part (B), and a post-pultrusion formed part (C), according to aspects of the present disclosure.

[0069] FIG. 15 panels A-D show a portion of a HAAM part (A), powder metal infused layers (B), a cross-section of a column formed via HAAM (C), and a perspective view of a column formed via HAAM (D), according to aspects of the present disclosure. [0070] FIG. 16 panels A-B show 3D renderings of columns formed via HAAM, according to aspects of the present disclosure.

[0071] FIG. 17 panels A-B show a cross-section of a beam formed via HAAM (A), and a perspective view of a beam formed via HAAM (B), according to aspects of the present disclosure.

[0072] FIG. 18 illustrates a structure produced via HAAM, according to aspects of the present disclosure.

[0073] FIG. 19 panels A and B illustrate structures produced via HAAM, according to aspects of the present disclosure.

[0074] FIG. 20 illustrates an automated HAAM manufacturing system, according to aspects of the present disclosure.

[0075] FIG. 21 shows an image of an exemplary mechanical testing sample system including samples that are parallel and perpendicular to print beads, according to aspects of the present disclosure.

[0076] FIG. 22 shows mechanical testing results, according to aspects of the present disclosure.

[0077] FIG. 23A shows an exemplary 0° linear raster pattern, which was used for manufacturing samples in group A, according to aspects of the present disclosure.

[0078] FIG. 23B shows an exemplary 90° linear raster pattern, which was used for manufacturing samples in group B, according to aspects of the present disclosure.

[0079] FIG. 23C shows an exemplary concentric raster pattern, which was used for manufacturing samples in group C, according to aspects of the present disclosure.

[0080] FIG. 24 shows an exemplary 4-point bend test system used to conduct the flexural testing, according to aspects of the present disclosure.

[0081] FIG. 25 shows an image of a conventional beam failure experienced during flexural testing. [0082] FIG. 26A is a graph which shows the amount of load under which the manufactured beams failed and the amount of deflection present in the beam before failure, according to aspects of the present disclosure.

[0083] FIG. 26B is a graph which shows the amount of load under which the manufactured beams failed and the amount of deflection present in the beam before failure, according to aspects of the present disclosure.

[0084] FIG. 26C is a graph which shows the amount of load under which the manufactured beams failed and the amount of deflection present in the beam before failure, according to aspects of the present disclosure.

[0085] FIG. 27 shows an exemplary system for overprinting onto a substrate to manufacture a hybrid workpiece, according to aspects of the present disclosure.

[0086] FIG. 28 shows an exemplary FEA model including a reduced weight profile, according to aspect of the present disclosure.

[0087] FIG. 29 shows exemplary cross-sections of specimens including 0% Reduction profile, 25% Reduction profile, 50% Reduction profile, 75% Reduction profile, and 100% Reduction profile, according to aspect of the present disclosure.

[0088] FIG. 30A shows an exemplary specimen including 0% Reduction profile, according to aspect of the present disclosure.

[0089] FIG. 30B shows an exemplary specimen including 25% Reduction profile, according to aspect of the present disclosure.

[0090] FIG. 30C shows an exemplary specimen including 50% Reduction profile, according to aspect of the present disclosure.

[0091] FIG. 30D shows an exemplary specimen including 75% Reduction profile, according to aspect of the present disclosure.

[0092] FIG. 30E shows an exemplary specimen including 100% Reduction profile, according to aspect of the present disclosure.

[0093] FIG. 31 A shows graphs of load displacement for a neat beam and a HAAM beam corresponding to 0% Reduction profile, according to aspects of the present disclosure. [0094] FIG. 31B shows graphs of load displacement for a neat beam and a HAAM beam corresponding to 25% Reduction profile, according to aspects of the present disclosure. [0095] FIG. 31C shows graphs of load displacement for a neat beam and a HAAM beam corresponding to 50% Reduction profile, according to aspects of the present disclosure.

[0096] FIG. 31D shows graphs of load displacement for a neat beam and a HAAM beam corresponding to 75% Reduction profile, according to aspects of the present disclosure.

[0097] FIG. 31E shows graphs of load displacement for a neat beam and a HAAM beam corresponding to 100% Reduction profile, according to aspects of the present disclosure.

[0098] FIG. 32 shows an exemplary FEA model of predicted deflection using a CFRTP substrate including an unsupported section, according to aspects of the present disclosure.

[0099] FIG. 33 shows an exemplary system to measure the deflection of a CFRTP substrate at the midspan of an unsupported section, according to aspects of the present disclosure.

[0100] FIG. 34 shows an exemplary system for overprinting on an unsupported CFRTP substrate, according to aspects of the present embodiments.

[0101] FIG. 35 is an image of an exemplary final part manufactured by overprinting on an unsupported CFRTP substrate, according to aspects of the present embodiments.

[0102] FIG. 36 shows graphs of load displacement for a neat beam, beams printed on an unsupported CFRTP substrate including span to depth ratios of 1, 2.5, 5, and 7.5, and a fully supported beam, according to aspects of the present disclosure.

DEFINITIONS

[0103] In this application, unless otherwise clear from context or otherwise explicitly stated, (i) the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and/or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; (iv) the terms “about” and “approximately” may be understood to permit standard variation as would be understood by those of ordinary skill in the relevant art; and (v) where ranges are provided, endpoints are included. In certain embodiments, the term "approximately" or "about" refers to a range of values that fall within 25%, 20%, 19%, 18%, 17%, 16%, 15%, 14%, 13%, 12%, 11%, 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, or less in either direction (greater than or less than) of the stated reference value unless otherwise stated or otherwise evident from the context (except where such number would exceed 100% of a possible value).

[0104] Comprising: A composition or method described herein as "comprising" one or more named elements or steps is open-ended, meaning that the named elements or steps are essential, but other elements or steps may be added within the scope of the composition or method. To avoid prolixity, it is also understood that any composition or method described as "comprising" (or which "comprises") one or more named elements or steps also describes the corresponding, more limited composition or method "consisting essentially of' (or which "consists essentially of) the same named elements or steps, meaning that the composition or method includes the named essential elements or steps and may also include additional elements or steps that do not materially affect the basic and novel characteristic(s) of the composition or method. It is also understood that any composition or method described herein as "comprising" or "consisting essentially of one or more named elements or steps also describes the corresponding, more limited, and closed-ended composition or method "consisting of (or "consists of) the named elements or steps to the exclusion of any other unnamed element or step. In any composition or method disclosed herein, known or disclosed equivalents of any named essential element or step may be substituted for that element or step.

[0105] Unitary, Continuous, Monolithic'. A workpiece (e.g., a hybrid workpiece) described herein is “unitary,” “continuous,” or “monolithic” (interchangeably) when it forms a single, unbroken unit. For example, as described herein, workpieces may be formed using multiple materials, methods and/or systems (e.g., multiple of the same or similar methods and/or systems, e.g., multiple different methods and/or systems). In certain embodiments, a unitary workpiece refers to a single workpiece that comprises multiple materials. DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

[0106] It is contemplated that systems, devices, workpieces, methods, and processes of the disclosure encompass variations and adaptations developed using information from the embodiments described herein. Adaptation and/or modification of the systems, devices, methods, and processes described herein may be performed by those of ordinary skill in the relevant art.

[0107] Throughout the description, where articles (i.e., articles of manufacture, i.e., workpieces), devices, and systems are described as having, including, or comprising specific components, or where processes and methods are described as having, including, or comprising specific steps, it is contemplated that, additionally, there are articles (i.e., articles of manufacture, i.e., workpieces), devices, and systems according to certain embodiments of the present disclosure that consist essentially of, or consist of, the recited components, and that there are processes and methods according to certain embodiments of the present disclosure that consist essentially of, or consist of, the recited processing steps.

[0108] It should be understood that the order of steps or order for performing certain action is immaterial so long as operability is not lost. Moreover, two or more steps or actions may be conducted simultaneously. As is understood by those skilled in the art, the terms “over”, “under”, “above”, “below”, “beneath”, and “on” are relative terms and can be interchanged in reference to different orientations of the layers, elements, and substrates included in the present disclosure. For example, a first layer on a second layer, in some embodiments means a first layer directly on and in contact with a second layer. In other embodiments, a first layer on a second layer can include another layer there between.

[0109] Headers are provided for the convenience of the reader and are not intended to be limiting with respect to the claimed subject matter.

I. Hybridized Advanced Additive Manufacturing

[0110] The present disclosure provides, among other things, additive manufacturing (i.e., 3D-printing) on top of a prefabricated workpiece or substrate where the prefabricated workpiece forms a part of and/or becomes part of the final part or component being made. Additive manufacturing onto a pre-existing workpiece or substrate is often referred to as “overprinting.”

[0111] FIG. 1 illustrates an exemplary method 110 of forming a workpiece (i.e., a hybrid workpiece) according to aspects of the present embodiments. At step 112, the method 110 may include fabricating (e.g., prefabricating) a workpiece or substrate via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, machining, and/or other processes. In some embodiments, the prefabricated workpiece may include a melt layer disposed on a bonding surface of the prefabricated workpiece (e.g., a top surface) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. The melt layer may include a thickening of the prefabricated workpiece on the surface(s) on which printing is to be performed. The melt layer may be formed via the same process the prefabricated workpiece is formed. At step 114, the method 110 may include moving the prefabricated workpiece to a 3D printing (or additive manufacturing) system. In some embodiments, the 3D printing (or additive manufacturing) system may include a powder bed type of system, a deposition (i.e., FDM, FFF, FGF) type of system, a binder jet system, a stereolithography system, and/or other types of additive manufacturing systems. At step 116, the method 110 may include heating (or preheating) a bonding surface and/or a melt layer of the prefabricated workpiece. In some embodiments, a melt layer is disposed on the bonding surface. At step 118, the method 110 may include measuring the temperature of the melt layer surface to ensure it is at or near (for example, within about 100°F, within about 50°F, within about 25°F, within about 15°F, within about 5°F) a glass transition temperature of the melt layer. At step 120, the method 110 may include actively and/or passively cooling the lower portions of the prefabricated workpiece to ensure the structural integrity of the prefabricated workpiece. At step 122, the method 110 may include printing, layer-by-layer, on top of the melt layer, thereby forming a melt bond between the prefabricated workpiece and subsequent print layers. At step 124, the method 110 may include cooling the printed and transition (i.e., at or near the melt layer) portions of the workpiece to form a consolidated, hybrid workpiece. In some embodiments, the method 110 of forming a workpiece enables doing so without the need for a structural adhesive since the bonding process as described herein may be achieved through molecular diffusion of one surface at the bond line to the other, and vice versa (i.e., the bond between the prefabricated workpiece and the print layer). In some embodiments, the prefabricated workpiece is actively heated. In some embodiments, the method 110 does not include actively heating the prefabricated workpiece and instead, heating is achieved through contact of the 3D printing material (for example, extrudate, in some embodiments) with the bonding surface of the prefabricated workpiece. For example, in some embodiments, the 3D printing material deposited onto the prefabricated workpiece transfers heat to the prefabricated workpiece and no other source of heat is required to heat the prefabricated workpiece. Accordingly, in some embodiments, the prefabricated workpiece may be at (or even below) room temperature (i.e., about 18-25 deg C) when the HAAM process is initiated.

[0112] FIG. 2 illustrates a method 210 of forming a workpiece (i.e., a hybrid workpiece) according to other aspects of the present embodiments. At step 212, the method 210 may include fabricating (i.e., prefabricating) a workpiece or substrate via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, machining, thermoforming, compression molding, continuous compression molding, stamp forming, and/or other processes. In some embodiments, the prefabricated workpiece may include a melt layer disposed on a bonding surface of the prefabricated workpiece (e.g., a substrate to be printed on) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. The melt layer may include a thickening of the prefabricated workpiece on the surface(s) on which printing is to be performed. The melt layer may be formed via the same process the prefabricated workpiece is formed. At step 214, the method 210 may include moving the prefabricated workpiece to a 3D printing (or additive manufacturing) system. In some embodiments, a build volume (i.e., an area in which an additive manufacturing takes place) is substantially enclosed (e.g., substantially airtight). In some embodiments, additive manufacturing takes place under an inert gas (e.g., argon, nitrogen) and/or under vacuum to avoid oxidation and/or combustion. In some embodiments, a build volume is heated. In some embodiments, the 3D printing (or additive manufacturing) system may include a powder bed recoater system for use with, for example, a binder jet, a selective laser sintering (SLS) system, selective laser melting (SLM) systems, direct metal laser melting (DMLM) systems, direct metal laser sintering (DMLS) systems, and/or other types of additive manufacturing systems. At step 216, the workpiece or substrate is optionally heated (e.g., prior to placement within a system or while in a system). At step 218, the method 210 may include filling a build area (or a portion thereof) with powder particles. At step 220, the method 210 may include heating powder particles and/or build volume (e.g., after the build area is filled). At step 222, the method may include heating (or preheating) the bonding surface (i.e., the melt layer) of the prefabricated workpiece. In certain embodiments, a laser (e.g., a CO2 laser, a diode-based laser) or other light source (e.g., IR light) are used to heat the bonding surface. At step 224, the method 210 may include measuring the temperature of the melt layer surface to ensure it is at or near (for example, within about 100°F, within about 50°F, within about 25°F, within about 15°F, within about 5°F) a glass transition temperature. At step 226, the method 210 may include coating a surface of the workpiece (e.g., the melt layer) with powder. In certain embodiments, a recoater is used to coat the surface. At step 228, the method 210 may include actively and/or passively cooling the lower portions of the prefabricated workpiece and/or powder bed to ensure the structural integrity of the prefabricated workpiece. For example, while additive manufacturing is occurring overtop the prefabricated workpiece, the temperature of the prefabricated workpiece must be maintained well below the glass transition temperature do ensure the prefabricated workpiece doesn’t itself melt while the HAAM process (i.e., i.e., additive manufacturing, i.e., overprinting) is occurring. At step 230, the method 210 may include printing, layer-by-layer, on top of the melt layer, thereby forming a melt bond between the prefabricated workpiece and subsequent print layers. In powder-based applications, printing may include addition of one or more layers of powder to the build area and/or workpiece (e.g., through use of a recoater) and, subsequently, fusing the powder together (e.g., using a laser) to form additional layers. At step 232, the method 210 may include cooling the printed and transition (i.e., at or near (i.e., within about 1 mm, within about 500 pm, within about 200 pm, within about 100 pm, within about 50 m, withing about 35 pm of) the melt layer) portions of the workpiece to form a consolidated, hybrid workpiece.

[0113] In some embodiments (e.g., metallic printing), 150pm may be nominal thickness of a powder layer. In embodiments of the systems and methods described herein where a laser is used as the sole heat source, a layer thickness that includes both the powder and the melt layer of the prefabricated workpiece that is no greater than about 200pm (e.g., 175pm or less, 150pm or less, e.g., from about 10pm to about 200pm, from about 25pm to about 150pm, from about 50pm to about 100 pm). For example, in some embodiments, the initial melt-binding is started by depositing a layer of about 25pm of powder on top of an approximately 100pm thick melt layer. The layers are then recoated with 25pm layers of powder added on top each time with corresponding 25 pm lowering movements of the build platform. Without wishing to be bound by theory, using microlayers of powder in connection with micro-adjustments of the build platform as well as a finely tuned power source (i.e., laser power) helps to facilitate melt bonding of the prefabricated workpiece with the added 3D printed layers. a. Fiber Components

[0114] In accordance with various embodiments, any application-appropriate fiber component s) may be used. By way of non-limiting example, fiber components may be naturally-derived fiber materials and/or synthetically-derived fiber materials. In many embodiments, exemplary fiber components include, but are not limited to, glass fibers (e.g., E-glass), carbon fibers, aramid fibers, basalt fibers, organic fibers (e.g., hemp fibers, e.g., wood-derived fibers), or any combination thereof. b. Thermoplastic Components

[0115] In accordance with various embodiments, any application-appropriate prefabricated thermoplastic components (i.e., prefabricated workpieces) may be used. By way of non-limiting example, prefabricated thermoplastic components may be or include thermoplastic polymers. In some embodiments, prefabricated thermoplastic polymers may be characterized as amorphous. In some embodiments, prefabricated thermoplastic polymers may be characterized as semicrystalline, including both amorphous components and crystalline components.

[0116] In accordance with various embodiments of the present disclosure, exemplary prefabricated thermoplastic polymers include but are not limited to polyethylene terephthalate (PET), polyethylene terephthalate glycol (PETg), polycarbonate, polyethylene (e.g., high-density polyethylene (HDPE), e.g., low-density polyethylene (LDPE)), polypropylene, poly etheretherketone, polyaryletherketone (e.g., low melt polyaryletherketone), polyamide (e.g., nylon 6, nylon 6 6, nylon 6 12, nylon 4,6 nylon 12, polyamide 12, etc.), acrylonitrile butadiene styrene, polylactic acid (PLA), polyvinylchloride (PVC), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), poly(methyl methacrylate) (PMMA), polyetherimide (PEI), polybenzimidazole (PBI), or any combination thereof.

II. Thermoplastic Composite Products

[0117] In accordance with various embodiments of the present disclosure, any of a variety of prefabricated thermoplastic products may be manufactured for use with the ELAAM process. By way of non-limiting example, prefabricated thermoplastic composite products are structural parts (e.g., structural members). In some embodiments, prefabricated structural composite parts may include, among other things, reinforcing bar (e.g., rebar), plates (e.g., flat plates), I-beams, Pi preforms (i.e., upside-down t-shaped preform), structural angles, structural channels (e.g., C-channels), hollow structural sections, or pipes.

Il Methods of Manufacturing Thermoplastic Composite Parts

[0118] The present disclosure provides, among other things, methods of manufacturing thermoplastic composite products that may be used as prefabricated workpieces in connection with a ELAAM process.

[0119] In some embodiments, a continuous forming machine 100, for example, presented in FIGs. 4A-4C, may be used for manufacturing disclosed prefabricated thermoplastic composite products and workpieces according to disclosed methods. In some embodiments, a continuous forming machine 100 comprises a loading unit 200 (e.g., for providing commingled thermoplastic composite materials), a tensioning unit 300 (e.g., for controlling a tension of commingled thermoplastic composite materials), a heating unit 400 (e.g., for heating commingled thermoplastic composite materials to produce heated feed materials), a forming unit 500 (e.g., for consolidating heated feed materials to produce consolidated materials), a cooling die 700 (e.g., for initially cooling consolidated materials), a cooling unit 800 (e.g., for further cooling consolidated materials to an ambient or roughly ambient temperature), a pulling unit 1400 (e.g., for pulling materials through the continuous forming machine), or any combination thereof. In FIGs. 4A-4C, like features are labeled with like numbers.

IV. Substrate Features

[0120] Joining and bonding are important components of manufacturing which allow for production of components for later assembly. Profiles specifically for edging, joining, or bonding (e.g., angles, flat plates, pi preforms) can be pultruded using, for example, CFM. In certain embodiments, profiles are tailored to match specific applications. An example of specific tailoring is curvature addition (for example, either locally or globally) to apply a pi preform to the interior of a vessel hull, to allow for bulkhead installation.

[0121] In certain embodiments, a hybrid workpiece can be created by printing materials as disclosed herein onto prefabricated workpieces / substrates having different profile features. For example, FIGs. 5A-5C show different profiles of prefabricated substrates. In FIGs. 5A-5C, prefabricated workpieces / substrates are shown in orange, while material deposited using additive manufacturing techniques (e.g., as described herein) are in blue. In certain embodiments, among other things, different substrate profiles can be used to provide printing and service benefits. For example, in certain embodiments, a channel profile (e.g., as shown in FIG. 5B, FIG. 5C) can be used to help prevent distortion of a substrate during additive manufacturing processes. In certain embodiments, a channel profile, for example, can provide structural benefits to a workpiece as it is in service (e.g., by enhancing resistance to external forces).

V. Reinforcing Components

[0122] Interlaminar strength deficiencies, or even layer delamination, often represent weakness areas and/or failure modes of 3D printed components. Accordingly, methods and systems described herein can address these deficiencies and provide additional benefits through use of reinforcing components (e.g., “rebars”) as described herein.

[0123] In certain embodiments, a hybrid workpiece can be created by printing material (via additive manufacturing) onto a prefabricated workpiece / substrate and incorporating reinforcing features. In certain embodiments, a multi-axis printer as described herein may be programmed to print around reinforcing components, leading to creation of a monolithic, reinforced hybrid workpiece. For example, as shown in FIG. 5D, additive manufacturing can be used to deposit material onto a prefabricated substrate 502 to create a hybrid workpiece 500. During and/or prior to the start of the additive manufacturing process, reinforcing components 504 can be placed within / embedded into an additive manufactured portion 506 of the hybrid workpiece. Subsequent layers of material can be deposited (e.g., by overprinting using a multi-axis 3D printing) onto previously deposited layers and reinforcing components. In certain embodiments, reinforcing components are coated with a melt layer.

[0124] In certain embodiments, reinforcing components comprise one or more reinforcing bars (“rebars”) having a profile and a length. In certain embodiments, a profile of a reinforcing bar is round or a polygon (e.g., square, rectangle, pentagon, triangle, etc.). In certain embodiments, a profile of a reinforcing bar is substantially continuous over its length. In certain embodiments, a profile of a reinforcing bar changes (e.g., in shape and/or size) along its length. In certain embodiments, a reinforcing bar can be pultruded or continuously formed (e.g., by a CFM technique described herein). In certain embodiments, reinforcing bars are formed using continuous fiber reinforced thermoplastics (CFRTP). In certain embodiments, reinforcing bars are coated with a melt layer.

[0125] In certain embodiments, reinforcing components have material properties that enable them to be incorporated into a hybrid workpiece (i.e., they are used as the prefabricated workpiece in the HAAM process) without causing significant workpiece deformation during and/or after printing. In certain embodiments, thermal expansion properties (e.g., a coefficient of thermal expansion) of a reinforcing component is similar to material deposited via additive manufacturing such that, as the hybrid workpiece is cooled and/or heated (e.g., during the printing process or during service), the hybrid workpiece does not crack and/or distort. In certain embodiments, reinforcing bars can be placed within two or more different layers of a hybrid manufactured workpiece.

[0126] In some embodiments, reinforcing components may be provided by a large- scale additive manufacturing (LSAM) as described herein (for example, in connection with FIG. 18) In some embodiments, reinforcing components may be provided by directly applied structural members (i.e., placed fibers) as described herein (for example, in connection with FIG. 20). In some embodiments, reinforcing components may include CFRTP components that are strategically placed within a LSAM part to provide localized strength and reinforcement. Accordingly, in some embodiments according to the present disclosure, an LSAM part may be produced using less material since the strategically-placed CFRTP component (or other reinforcing component) provides strength, therefore reducing the required cross-section or thickness needed to meet the strength requirement of the LSAM part.

VI. Thermal and Mechanical Induced Stresses and Strains

[0127] Among other things, the present disclosure provides methods and systems for identifying and/or predicting mechanical and/or thermal-induced changes (e.g., mechanical deformations, thermo-mechanical deformations, thermal deformations) to composite workpieces manufactured using the additive manufacturing methods and systems described herein.

[0128] Mechanical forces generated during layer-by-layer manufacturing processes may result in deformations (e.g., mechanical deformations) within a workpiece. Mechanical deformations are a result of mechanical stresses and strains developing due to additional weight of material being deposited onto a workpiece. Among other things, deformations of a workpiece due to mechanical forces may alter the utility, serviceability, and manufacturability of the workpiece. Accordingly, methods and systems for reducing deformations due to mechanical forces induced by layer-by-layer deposition are desirable. [0129] Thermal-induced temperature gradients generated during layer-by-layer manufacturing processes may result in thermal deformations within the workpiece. Thermal deformations are a result of thermal stresses and strains developing due to temperature gradients (i.e., thermal gradients). Among other things, deformations of a workpiece due to thermal gradients may alter the utility, serviceability, and manufacturability of the workpiece. Accordingly, methods and systems for reducing deformations due to thermal gradients are desirable.

[0130] In some embodiments, Hybridized Advanced Additive Manufacturing (HAAM) requires heating both a substrate (e.g., a portion of the prefabricated workpiece to be printed on) and a material (e.g., a thermoplastic material, a metallic material, a ceramic material) to be deposited onto a substrate to an elevated temperature to generate a composite workpiece. Methods and systems for HAAM are described herein. In certain embodiments, prior to or during generation of a workpiece, a thermo-mechanical analysis of a composite workpiece is undertaken. Thermal and mechanical analyses of a workpiece may be used to determine the degree to which thermal gradients and mechanical forces introduced during HAAM (e.g., by layer-by-layer printing of materials, by heating a substrate (e.g., a portion of the prefabricated workpiece to be printed on)) generates distortions in the workpiece. [0131] In certain embodiments, thermal and mechanical analyses can be generated prior to and/or during the creation the composite part. In certain embodiments, thermal and mechanical analyses are performed using finite element analysis (FEA) methods. In certain embodiments, the thermal and mechanical analyses are based on one or more parameters used to fabricate a printed portion of a workpiece. For example, parameters involved in fabricating a printed portion of a workpiece include the temperature of the substrate (e.g., before and/or during layer-by-layer deposition), a tool path of a print head of an additive manufacturing system (e.g., as implemented and/or controlled using G-code), temperature of the deposited materials, material properties of the substrate, density of material deposited on a substrate, and part geometry. In certain embodiments, temperature sensing devices are used to monitor (e.g., measure) the temperature of a composite part and/or an environment surrounding a part during layer-by-layer deposition of material. Exemplary devices include, but are not limited, to infrared sensing devices (e.g., cameras) and temperature probes. In certain embodiments, devices are used to observe the geometry of a composite part during layer-by-layer deposition of material. Exemplary devices used to monitor part geometry, but are not limited, to optical sensing devices (e.g., cameras, lasers).

[0132] In certain embodiments, thermo-mechanical analyses conducted prior to and/or during the additive manufacturing process identify that thermal-induced stresses and/or strains will produce a distortion beyond an acceptable threshold. Accordingly, methods and systems are implemented to mitigate the effect of thermal distortion on a composite part during and/or prior to printing by reducing the thermal gradients in a workpiece. For example, in certain embodiments, cooling of the part and/or print head can be used to mitigate temperature gradients during printing. In certain embodiments, a tool path and/or speed can be changed to mitigate thermal distortion.

VII. Printing Systems

[0133] The present disclosure provides for, among other things, systems for manufacturing hybrid workpieces.

[0134] FIG. 6 is an illustrative embodiment of a system used for manufacture of workpieces (e.g., hybrid workpieces) using a nozzle-based or deposition-based 3D printing modality. In some embodiments, a workpiece or substrate 604 may be fabricated (i.e., prefabricated) via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, machining, and/or other processes). In some embodiments, a prefabricated workpiece 604 includes a melt layer 602 disposed on a top surface (i.e., the substrate to be printed on) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. In some embodiments, workpiece fabrication 600 occurs in a separate system from a HAAM system 606. In some embodiments, workpiece fabrication occurs in the same system as a HAAM system 606. A HAAM system 606 is a 3D printing system that enables printing on a prefabricated workpiece, as described herein. In some embodiments, a HAAM system 606 includes one or more heat sources (e.g., 608, 610, 612) for heating (or pre-heating) a build volume used for 3D printing, a workpiece / substrate 618, melt layer of the workpiece / substrate 616, extrudate and/or print layer 622, and extruder(s) 614 of the system. In some embodiments, heat sources are used to locally heat a melt layer and/or extrudate 610. In some embodiments, heat sources include a blower 612. In some embodiments, one or more blowers are used for distribution of heat across target surfaces or within the build volume. In some embodiments, a cooling source 624 is used to actively and/or passively cool a lower portion of a prefabricated workpiece. For depositionbased 3D printers, a printer may include one or more extruders 614 (e.g., discharge nozzles) for extrusion of an extrudate into a print layer 622 onto a workpiece 618. In some embodiments, the system 606 may include one or more sensors 628 (i.e., an IR sensor) directed at the bonding surface to measure the substrate temperature during the HAAM process.

[0135] FIG. 7 is an illustrative embodiment of a system used for manufacture of workpieces (e.g., hybrid workpieces) using a powder bed modality. In some embodiments, a workpiece or substrate 704 may be fabricated (i.e., prefabricated) via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, machining, and/or other processes). In some embodiments, a prefabricated workpiece 704 includes a melt layer 702 disposed on a top surface (i.e., the substrate to be printed on) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. In some embodiments, workpiece fabrication 700 occurs in a separate system from a HAAM system 706. In some embodiments, workpiece fabrication occurs in the same system as a HAAM system 706. A HAAM system 706 is a 3D printing system. In some embodiments, a HAAM system 706 employs a powder bed-based 3D printing modality (e.g., Direct Metal Laser Melting (DMLM), Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM), or other “powder bed” modalities). In some embodiments, a HAAM system 706 includes one or more heat sources for heating (or pre-heating) a build volume used for 3D printing, the workpiece 708, a melt layer of the workpiece 710, a print layer, a powder bed 712, and/or build platform 714 of the system. In some embodiments, heat sources are used to locally heat a melt layer and/or powder bed (712). In some embodiments, the HAAM system substantially encloses a workpiece so that fusion of the powder (e.g., via sintering, melting, etc.) occurs under an inert gas (e.g., nitrogen, argon) and/or under a vacuum. In some embodiments, a cooling source is used to actively and/or passively cool a lower portion of a prefabricated workpiece. For powder-bed based 3D printers, a powder bed 712 contains powder particles which are fused together through the use of a laser 716 or other suitable high energy heat source (e.g., electron beams), which generates sufficient amounts of heat to fuse (e.g., melt, sinter) powder particles together which are spread onto the surface of a workpiece 708. In certain embodiments, the thickness of the powder layer is from about 1pm to about 300pm, from about 10pm to about 250pm, from about 100pm to about 200pm, from about 125pm to about 175pm, from about 140pm to about 160pm. In certain embodiments, a plurality of light sources may be used in a HAAM system. In certain embodiments, a light source 716 may be used to heat (or pre-heat) a melt layer prior to and/or during the melting process. In some embodiment, a support system 720 (e.g., a gantry, actuators, etc.) is used to move and aim a light / energy source 716 (e.g., an infra-red light source, a laser, electron beams) at the surface of the powder in order to fuse the powder particles and/or melt the melt layer 710. In certain embodiments, a plurality of light / energy sources 716 are mounted to the support system 720. Once a layer has been fused together, the build platform 714 moves the object downward and a re-coater 718 (e.g., a re-coater arm) is used to spread a new layer of powder over the surface of the bed. Subsequently, a light / energy source 716 is used to fuse powder of the following layer. In some embodiments, the system 706 may include one or more sensors 728 (i.e., an IR sensor) directed at the bonding surface to measure the substrate temperature during the HAAM process.

[0136] FIG. 8 is an illustrative embodiment of a system 806 used for manufacture of workpieces (i.e., hybrid workpieces) with binder jet printing. In some embodiments, a workpiece or substrate 804 may be fabricated (i.e., prefabricated) via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, machining, and/or other processes). In some embodiments, a prefabricated workpiece 804 includes a melt layer 802 disposed on a top surface (i.e., the substrate to be printed on) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. In some embodiments, workpiece fabrication 800 occurs in a separate system from a HAAM system 806. In some embodiments, workpiece fabrication occurs in the same system as a HAAM system 806. AHAAM system 806 is a 3D printing system that enables printing on a prefabricated workpiece, as described herein. In some embodiments, a HAAM system 806 employs a powder-based 3D printing modality (e.g., binder jet printing). In some embodiments, a HAAM system 806 includes one or more heat sources for heating (or pre-heating) a build volume used for 3D printing, workpiece 808, melt layer of the workpiece 810, print layer, powder bed 812, and/or build platform 814 of the system. In some embodiments, heat sources are used to locally heat a melt layer and/or powder bed 812. In some embodiments, a cooling source is used to actively and/or passively cool a lower portion of a prefabricated workpiece 804. For binder-jet based 3D printers, a powder bed 812 contains granulated powder particles which are fused together through the deposition of a liquid binder (e.g., an adhesive) 822 onto the surface of a workpiece 808. In certain embodiments, the thickness of the powder layer is from about 1pm to about 300pm, from about 10pm to about 250pm, from about 100pm to about 200pm, from about 125pm to about 175pm, from about 140pm to about 160pm. In certain embodiments, a plurality of print heads (or print nozzles) may be used in a HAAM system. In certain embodiments, a light / energy source (e.g., infra-red, UV, laser, etc.) may be used to cure a layer after deposition of a liquid binder. In some embodiment, a support system 820 (e.g., a gantry, actuators, etc.) is used to move print head(s) over the surface of the powder in order to deposit liquid binder 822 to fuse powder particles and/or the melt layer 810. In certain embodiments, a plurality of light sources 816 are mounted to the support system 818. In certain embodiments, once a layer has been fused together, the build platform 814 moves the object downward and a re-coater 818 (e.g., a re-coater arm) is used to spread a new layer of powder over the surface of the bed and workpiece. Subsequently, liquid binder 822 is used to fuse powder of the following layer(s). Once initially formed (i.e., via a binder jet process) as described above, the hybrid workpiece may subsequently be cured (for example, in an oven or autoclave) such that it solidifies. In some embodiments, the system 806 may include one or more sensors 828 (i.e., an IR sensor) directed at the bonding surface to measure the substrate temperature during the HAAM process.

[0137] Alternative 3D printing modalities such as stereolithography (SLA) methods may also be employed in a HAAM system to create a hybrid workpiece. FIG. 9 is an illustrative embodiment of a system used for manufacture of workpieces (e.g., hybrid workpieces) with stereolithography (SLA) 3D printing or another fluid-based 3D printer. In some embodiments, a workpiece or substrate 904 may be fabricated (i.e., prefabricated) via one or more fabrication processes (e.g., investment casting, injection molding, forging, composite manufacturing (polymer matrix composites (PMC), metal matrix composites (MMC), carbon matrix composites (CMC)), continuous forming via continuous forming machine (CFM), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, machining, and/or other processes). In some embodiments, a prefabricated workpiece 904 includes a melt layer 902 disposed on a top surface (i.e., the substrate to be printed on) such that additional material is available on the prefabricated workpiece without impacting the structural fidelity of the prefabricated workpiece. In some embodiments, workpiece fabrication 900 occurs in a separate system from a HAAM system 906. In some embodiments, workpiece fabrication occurs in the same system as a HAAM system 906. In some embodiments, a HAAM system 906 includes one or more heat and/or light sources 916 for heating (or pre-heating) and/or activating the melt layer of the workpiece 910 and fusing / hardening 3D printed layers. In some embodiments, heat sources 916 are used to locally heat the melt layer 910. In some embodiments, the heat source is a light source (e.g., an infra-red light, e.g., an infra-red LED). For SLA-based 3D printers (i.e., stereolithography), a fluid reservoir 912 contains a liquid (e.g., a liquid resin, e.g., a photocurable (i.e., IR curable) resin), which is fused through the exposure of the liquid to a light source (e.g., LEDs, lasers, etc.) at a particular wavelength. For example, according to the present disclosure, in some embodiments, the HAAM process may include using SLA to print with a photocurable polypropylene prototype material over a polypropylene (PP) prefabricated workpiece. The bottom surface (or a portion thereof) of the fluid reservoir 912 is substantially optically transparent and allows for light to pass through the bottom surface to the liquid in the reservoir. In certain embodiments, a plurality of light sources 916 may be used in a HAAM system. In some embodiments, a build platform 914 (e.g., a gantry, actuators, etc.) is used to move the workpiece/substrate as each layer of print material is fused together. Once a layer has been fused together, the build platform 914 moves the object upward and new material enters the space between the workpiece and the light source(s). In certain embodiments, a melt layer on the workpiece may be activated / cured using, for example, a light source (e.g., IR (infrared) source (e.g., an LED light)) or other heat source. In certain embodiments, the heat / light source is provided by a pre-embedded light source (e.g., within a fluid reservoir or workpiece). In certain embodiments, post-processing curing steps may be employed to solidify / cure the workpiece. In some embodiments, the system 906 may include one or more sensors 928 (i.e., an IR sensor) directed at the bonding surface to measure the substrate temperature during the HAAM process.

VIII. Printing Parameters a. Strength Studies

[0138] The present examples describe how the overprinting bond strength is tested to show variations with changes in targeted factors (e.g., print and substrate temperatures, print pattern, etc.).

[0139] FIG. 3 is an illustrative embodiment of hybrid workpiece testing 310 (e.g., how the overprinting bond strength is tested (e.g., characterized)). Overprinting is a process where material is deposited using a 3D printing assembly onto an existing prefabricated part / substrate. In the left panel of FIG. 3, a hybrid workpiece is shown with a top, layer (identified as “LSAM”; Large-Scale Additive Manufacturing) created by use of additive manufacturing and a substrate of pultruded thermoplastic composite manufactured by a Continuous Forming Machine (identified as “CFM”). In the present example, the overprinted layer is deposited using additive manufacturing methods described herein for LSAM onto a continuously formed substrate. However, a person of skill in the art would be able to employ methods and systems described herein to modify manufacturing techniques as necessary so other additive manufacturing techniques could be used in overprinting, and such that other manufacturing processes could be used to form the prefabricated workpiece. [0140] Overprinting bond strength can be tested by inducing bond failure through, for example, pull, peel, and shear tests. Targeted factors including, but not limited to, print and substrate temperatures can be tested accordingly. The type of failure mode of a hybrid workpiece (e.g., where and how a failure occurred) and amount of force required is indicative of the strength of the bond between the prefabricated part and the additive manufactured printed part (i.e., or 3D-printed portion of the final hybrid part). In certain testing modes, strengths of materials used to create the workpiece may also be determined. b. Temperature Parameters

[0141] The present examples show exemplary substrate and nozzle temperatures for various material systems using a nozzle-based or deposition-based 3D printing modality (e.g., Fused Filament Fabrication (FFF), Fused Granulate Fabrication (FGF), Fused Deposition Modeling (FDM), or another other nozzle / deposition modality).

[0142] In some embodiments, methods involving deposition of thermoplastics onto a prefabricated workpiece comprising thermoplastics (e.g., reinforced thermoplastics) require heating (i.e., preheating) the prefabricated workpiece surface / substrate and the nozzle used to deposit (i.e., extrude) the thermoplastic material onto the prefabricated surface / substrate. Table 1 shows different systems of materials with corresponding ranges of temperature of the prefabricated workpiece (e.g., the CFRTP substrate) and the range of temperatures at which a nozzle is heated to extrude the material onto a heated (i.e., preheated) substrate.

Table 1. Substrate and Extruder Temperatures.

[0143] In certain embodiments, the material being extruded is the same class of material of the substrate / workpiece. For example, the class of material may include: polycarbonates (PC), polypropylenes (PP), polyethylene terephthalate glycolpolycarbonates (PETG), polyethylenes (PE), acrylonitrile butadiene styrenes (ABS), polylactic acids (PA), polyvinylchlorides (PVC), polyamide 12, ceramics, aluminum, stainless steel, titanium, nickel alloys, copper, tungsten, maraging steel, etc. In certain examples, the class of material is a thermoplastic. In the present example, the temperature of the nozzle used to print onto the CFRTP workpiece / substrate is equal to or higher than the temperature of the surface of the CFRTP workpiece / substrate. For example, in Table 1, a PETG-based extrudate is printed onto a continuous fiber reinforced thermoplastic (CFRTP) substrate comprised of PEG reinforced with, for example, e-glass. The PETG-based extruder nozzle is heated to a temperature from about 207°C to about 253°C, while the CFRTP substrate surface is heated to a temperature from about 85°C to about 207°C. In another example, the extrudate is a PC-based extrudate and is printed onto a CFRTP substrate comprised of PC reinforced with, for example, carbon. The extruder nozzle for the PC-based extrudate is heated to a temperature from about 257°C to about 314°C, while the CFRTP substrate surface temperature is heated to a temperature from about 85°C to about 207°C. In some embodiments, the extrudate is a PA12-based extrudate and is printed onto a CFRTP substrate comprised of PA12 reinforced with, for example, e-glass. The extruder nozzle for the PA12- based extrudate is heated to a temperature from about 225°C to about 275°C, while the CFRTP substrate surface temperature is heated to a temperature from about 50°C to about 225°C. In some embodiments, the extrudate is a PP -based extrudate and is printed onto a CFRTP substrate comprised of PP reinforced with, for example, e-glass. The extruder nozzle for the PP -based extrudate is heated to a temperature from about 198°C to about 254°C, while the CFRTP substrate surface temperature is heated to a temperature from about 50°C to about 198°C.

[0144] Referring still to Table 1, by heating the extruded material (i.e., 3D-printed material) to a temperature above that of the prefabricated workpiece (i.e., at the bonding surface of melt layer) the prefabricated workpiece itself may be maintained at a lower temperature, thereby ensuring that the structural integrity of the prefabricated workpiece is maintained through the ELAAM process. At the same time, when the print layer contacts the bonding surface (or melt layer) of the prefabricated workpiece, the higher temperature of the print layer and the lower temperature of the bonding layer of the prefabricated workpiece are brought into approximate equilibrium (i.e., the melt layer / bonding surface temperature rises and the print layer temperature decreases) thereby ensuring that the melt layer / bonding surface is sufficiently heated to enable melt bonding to occur. For example, in the case of PETG, in some embodiments, the print layer temperature and melt layer / bonding surface temperatures may reach an equilibrium in a range of about 130°C to about 170°C, or from about 140°C to about 160°C, or from about 147°C to about 155°C, thereby allowing meltbonding to occur between layers. In some embodiments, the substrate (i.e., prefabricated workpiece) surface temperature is heated up to at least the glass transition temperature, while the nozzle temperature is heated to a higher temperature than the substrate surface temperature. As illustrated in Table 1, the nozzle temperature ranges may overlap with corresponding melting temperature ranges for each respective material shown. Accordingly, in some embodiments, the prefabricated workpiece is heated to at least a glass transition temperature while the nozzle (i.e., extrusion nozzle and/or printer discharge nozzle) is heated to a temperature within the melting temperature range of the material being printed. [0145] Still referring to Table 1, the bonding process according to the present embodiments may be achieved through molecular diffusion of a bonding surface (i.e., of the prefabricated workpiece) to print material deposited thereon. The material of the bonding surface is of the same class of materials as the print material. Heat is applied to the bonding surface. In some embodiments, the bonding surface is actively heated (i.e., heat is applied) via flame, IR source, UV source, laser, conduction, convection, plasma heating, resistance heating, inductive heating, and other types of heating, as described herein. In some embodiments, heat is applied to the bonding surface as a result of the print material deposited thereon (i.e., with no other heat source used for heating the bonding surface). In some embodiments, the interface between the bonding surface and the print layer reaches a temperature at or near a melt temperature and/or a glass transition temperature, as described herein. In some embodiments, the bonding surface may be actively heated to a temperature below the glass transition temperature, and may be subsequently further heated to at or near the glass transition via the print material deposited thereon. In some embodiments, amorphous materials (i.e., amorphous thermoplastics) with no defined melt temperature may be used. In some embodiments, semi-crystalline materials may be used. In some embodiments, molecular diffusion may occur at a range of temperatures, including temperatures below the melt temperature and/or glass transition temperature.

EXEMPLIFICATION

[0146] In order that the application may be more fully understood, the following examples are set forth. It should be understood that these examples are for illustrative purposes only and are not to be construed as limiting in any manner.

Example 1: Analysis of Thermal Distortions

[0147] The present example demonstrates the effect of thermal distortions onto a hybrid workpiece part due to the severe thermal gradient present through the workpiece as it is printed using methods and systems described herein.

[0148] In certain embodiments described herein and in the present example, Hybridized Advanced Additive Manufacturing (HAAM) requires heating both the prefabricated workpiece and 3D print material to an elevated temperature in order to facilitate printing and workpiece-print adhesion. However, as individual 3D print beads are deposited onto the workpiece, heat transfers between the prefabricated workpiece and previously deposited beads. The heat transfer between the prefabricated workpiece and the deposited beads induces thermal stresses and distortions due to the severe thermal gradient through the part. Predicting, understanding, and accounting for the thermal stresses and distortions requires advanced numerical modeling.

[0149] Thermo-mechanical analysis of parts produced by HAAM is a two-step process which uses the finite element method to solve the loosely coupled heat transfer and structural differential equations. In both analyses, the substrate (e.g., a prefabricated workpiece) is initialized, and then individual 3D print elements are activated sequentially following modified G-code instructions corresponding to that supplied to the 3D printer. During the first analysis, the heat transfer problem is solved, where thermal energy is allowed to transfer through the part with the resulting nodal temperatures saved at each step. FIG. 10, panels A-C show the computed temperatures of a prefabricated workpiece before printing (FIG. 10, panel A), those of a composite workpiece mid-way through printing (FIG. 10, panel B), and a composite workpiece after printing was completed at the beginning of final cooling (FIG. 10, panel C). As can be seen, a significant thermal gradient develops through the material being printed onto the prefabricated workpiece (FIG. 10, panel B). As printing continues, heat is shed (i.e., dissipated) throughout the part and to the environment (FIG. 10, panel C).

[0150] The nodal temperatures calculated during the heat transfer analysis are used as inputs to the structural analysis. As the temperatures of the part develop, thermal stresses are induced which cause increased thermal strains due to confinement and increased thermal gradients. The increased thermal stress also induces distortion in the part. FIG. 11, panels A-C show this distortion (significantly exaggerated for clarity) as the part is printed. As can be seen, a concave bend is formed due to the continual deposition and contraction of new, hot 3D printed layers.

[0151] As FIG. 11, panels A-C show, thermal distortions of HAAM produced parts can be significant and, if not properly taken into account, can significantly affect the utility and serviceability of the final part. However, thermo-mechanical analysis of the HAAM process can help to predict these distortions and internal stresses before initiation of manufacturing. Additionally, similar analyses can be used to test mitigation strategies (e.g., as described herein) prior to implementation. In this way, costly part failures and trial -and- error mitigation strategies can be avoided.

Example 2: Analysis of AM and Substrate Temperatures

[0152] The present example demonstrates the effect of substrate and extrudate temperature on longitudinal and transverse bond strength between CFM pultruded material and additive manufacturing (AM) materials. The present example was also used to verify substrate (e.g., a workpiece being printed on) heating methods. Among other things, the present example demonstrates that, as the temperature of the substrate and extrudate are increased, the bond strength between the two materials correspondingly increases under certain conditions.

[0153] In the present example, additively manufactured features were printed onto a CFM pultruded substrate to create a hybrid workpiece to test the longitudinal and transverse bond strength between the AM and CFM materials. The material deposited by additive manufacturing was Techmer Electrafil PETg 1711 3DP carbon fiber reinforced polyethylene terephthalate glycol (PETg), which contains 20% by weight carbon fibers in a PETg matrix. The thermoplastic (TP) tape used was an Avient e-glass / PETg tape which comprised 58% fiber by weight. The substrate onto which the AM material was deposited was a CFRTP plate including 16 layers with a laminate orientation code [0/90]8s. The CFRTP panel included a nominal width of 12 inches, a nominal length of 15 inches, and a nominal thickness of 0.125 inches. The CFRTP panel was consolidated on a thermoforming press at a temperature of 170 °C (i.e., 340 °F) and a pressure of 110 psi. The material properties of the AM and TP tape are provided in Table 2 below.

Table 2. Material Properties of AM material and TP Tape.

[0154] FIG. 27 shows an exemplary system 1100 for overprinting onto a substrate to create a hybrid workpiece, according to aspects of the present disclosure. In some embodiments, the system 1100 includes a BAAM 3D printer 1110, a CFRTP plate 1112 and a heating system 1114. In some embodiments the heating system 1114 includes a plate style heating system, i.e., a heating platen. In some embodiments, the heating platen 1114 includes two thick aluminum plates with embedded cartridge heaters placed against each other, and sealed via a high-temperature polyimide tape to form a single large heating surface. One or more thermocouples are included to enable monitoring the temperature of the heating surface. Each aluminum plate may further include one or more vacuum pass- through ports to allow the CFRTP panel 1112 to be held to the heating surface using vacuum pressure. A fine stainless-steel mesh may be used as a vacuum flow media to provide an even pressure across the entire area of the CFRTP 1112. The heating platen 1114, therefore, may simultaneously heat and vacuum hold-down the CFRTP panel 1112. Thin plywood spacers (e.g., sheets) may be used underneath the heating platen 1114 to provide thermal insulation (e.g., to limit heat loss to the print bed). In some embodiments, the heating platen 1114 is capable of reaching a temperature of approximately 200 °C (390 °F). In some embodiments, the heating platen 1114 maintains a target temperature at the top surface of the CFRTP panel 1112 within a margin of ±3 °C. [0155] Temperature combinations were selected by using two factor, full factorial comparative design. For each combination of temperatures, AM material was overprinted with a melt at temperature Ti onto a CFRTP substrate at temperature T2.

[0156] To manufacture a hybrid workpiece (i.e., specimens for the analysis), the CFRTP panel 1112 was aligned on the heating platen 1114, and the entire perimeter of the panel 1112 was firmly taped to form a vacuum seal. Two thermocouples were taped to the top surface of CFRTP panel 1112, near the edges and away from the overprinting region. A third thermocouple was directly attached to the heating platen 1114. The three thermocouples were connected to a data logger. Subsequently, the CFRTP panel 1112 was heated for a period of about 20 to 40 minutes, depending on the target substrate temperature (T2). Once the target temperature T2 was reached, the process was held for a brief period to ensure stability of the substrate temperature before overprinting began. During the 3D printing cycle, single layers of AM material at a specified melt temperature (Ti) were printed onto the heated CFRTP substrate, while the substrate temperature was monitored to ensure that it remained within approximately ±3°C of the target value T2. After overprinting was completed, the hybrid panel was allowed to cool down to room temperature, while keeping the vacuum hold-down active. The hybrid panels were subsequently removed from the heating platen 1114 and machine couponed and tested according to American Society for Testing and Materials (ASTM) D3846-08. The testing standard is incorporated by reference in its entirety. ASTM D3846-08 is a test generally useful in measuring shear strength of two materials.

[0157] FIG. 21 shows an image of an exemplary testing sample system where samples parallel and perpendicular to print beads were tested to characterize the orthotropy of the overprinting process. In FIG. 21, the print beads run from left to right in the image. The results of the ASTM D3846 in-plane shear strength tests are shown below in Table 3. FIG. 22, panels A and B are 3D graphs which correspond to the ASTM test results in Table 3.

Table 3. ASTM Test Results for Hybrid Workpiece.

[0158] A two-way ANOVA with a confidence interval of 5% was performed on the results shown in Table 3 to analyze the effects of the process temperatures and their interaction on the shear strength results. The results of the two-way ANOVA analysis are presented in Table 4.

Table 4. Two-Way ANOVA of AST Al Test Results.

[0159] From the data presented in Table 3 and the graphs shown in FIG. 22, the respective impacts of melt temperature (Ti) and substrate temperature (T2) on longitudinal and transverse (i.e., perpendicular to print beads) shear strength were quantified. As shown in Table 3, while holding other factors constant, the respective longitudinal or transverse shear strength improved (i.e., increased) each time T2 increased. Therefore, by pre-heating the substrate according to the methods and systems described herein, the resulting longitudinal or transverse shear strength can be improved. In addition, as T 1 and T2 both increase, the longitudinal shear strength tends to increase as well. Accordingly, higher processing temperatures may lead to greater bond strength (at least in the longitudinal direction). Mechanical factors, such as voids left by the print process parallel to the beads and/or the orthotropy of the short fiber reinforcement within the AM material may also play a role on resulting shear strength. The covariance (COV) of each of the parallel and perpendicular prints are shown in Table 3 as well. Example 3: Raster Investigations

[0160] Among other things, the present example analyzes the effects of printing patterns (e.g., “AM raster pattern”) on thermal distortion of a hybrid workpiece, and the final flexural strength of the workpiece. Additionally, the results comparatively determine which raster pattern produced an optimal combination of low distortion and high flexural strength.

[0161] In the present example, a series of beam specimens with different AM raster patterns were created using the system 1100, as described in Example 2. The CFRTP substrate panels included a length of 37 inches, a width of 5 inches, and a thickness of 1/8 inches. After printing, each specimen was allowed to cool and then measured to determine maximum longitudinal and lateral thermal distortions. Additionally, each specimen’s flexural strength was tested by using a 4-point bend test (e.g., as shown in FIG. 24).

[0162] FIG. 23A shows an exemplary 0° linear raster pattern, which was used for manufacturing samples in group A (lighter shading corresponds to start of the print). Material is deposited onto a CFRTP pultruded plate using the raster pattern as shown in the corresponding photograph.

[0163] FIG. 23B shows an exemplary 90° linear raster pattern, which was used for manufacturing samples in group B (lighter shading corresponds to start of the print). Material is deposited onto a CFRTP pultruded plate using the raster pattern as shown in the corresponding photograph.

[0164] FIG. 23C shows an exemplary concentric raster pattern, which was used for manufacturing samples in group C (lighter shading corresponds to start of the print).

Material is deposited onto a CFRTP pultruded plate using the raster pattern as shown in the corresponding photograph.

[0165] The magnitude of thermal distortions was measured as the maximum gap developed between the print bed and the bottom of the specimen. This was accomplished by supporting specimens on both ends with blocks of known height on a flat surface, and measuring the distance between the bottom of the specimen and the flat surface at several locations along its span on either side. Longitudinal distortion was calculated as the difference between the known height of the blocks and the measured distance, with negative values indicating a concave distortion and positive values indicating a convex distortion. Transverse distortion was calculated as the difference between the determined longitudinal distortions on opposing sides of the specimen. Table 5 below shows the results from the longitudinal and lateral distortions for samples in groups A, B, and C manufactured using the methods described here.

Table 5. Thermal Distortion Results.

[0166] After printing the material onto the CFRTP pultruded plates, it was found that samples manufactured using a 0° linear raster pattern (group A) had minimal longitudinal distortion. Samples in manufactured using a concentric raster pattern (group C) had no appreciable longitudinal distortion. Samples manufactured using the 90° linear raster pattern had significant longitudinal distortion as compared to specimens manufactured in Groups A and C. In addition, no specimen displayed any significant transverse distortion.

[0167] After evaluation of thermal distortions, the specimens were tested in 4-point bending to failure test. FIG. 24 shows an exemplary 4-point bend test used to conduct the flexural testing. Flexural testing results are shown below in Table 6.

Table 6. Flexural Testing Results.

[0168] The present experiment compares neat AM beams (e.g., those printed without an underlying CFTRP pultruded plate as a substrate) with a HAAM beam (e.g., those printed onto a CFTRP pultruded plate). For each of the specimen groups, the flexural moment at failure was much higher for the HAAM beam than the neat AM beam. The addition of a CFRTP pultruded plate significantly increased the flexural stiffness and strength of the workpiece. The increase in flexural strength is most pronounced for the 90° raster pattern (Group B). While the neat AM beam with 90° raster pattern exhibited the lowest flexural strength, the increase in strength via hybridization was about an order of magnitude.

[0169] When testing the HAAM beams, it was found that the beams tended to fail in shear as shown in, for example, FIG. 25. The crack developed through the HAAM beam in FIG. 25 is present through the 3D printed layers, but does not pass through the CFRTP layer. Additionally, it was found that shear failure occurred before delamination in HAAM beams. Accordingly, the AM-CFRTP bond is not a limiting factor.

[0170] FIGS. 26A-26C are graphs which show the amount of load under which the manufactured beams failed, and the amount of deflection present in the beam before failure. Each graph presents both neat AM beams (e.g., those printed without an underlying CFTRP pultruded plate as a substrate) and HAAM beams (e.g., those printed onto a CFTRP pultruded plate) manufactured using a raster pattern corresponding to the identified group.

Example 4: Beam Lightweighting

[0171] The present example demonstrates the ability of HAAM to produce finished parts whose weight are significantly reduced while maintaining or exceeding the strength of the corresponding neat LAAM parts.

[0172] In this example, light weighting was achieved via removal of material from the bulk specimens used in the previous examples. In some embodiments, the removal of material from a bulk specimen may result in a more optimally designed cross-section. Preliminary analyses were performed to determine feasible weight reductions while maintaining ultimate loads for a neat LAAM beam. The results of these analyses suggested that significant LAAM weight reductions (for example, greater than 60% weight reduction) are theoretically possible, however, to ensure manufacturability, a profile was selected to balance weight reduction and printing constraints. FIG. 28 shows an exemplary FEA image of the selected profile, according to aspect of the present disclosure. This profile was designated the 100 profile (i.e., 100% Reduction profile) as it represented 100% of the feasible weight reduction. [0173] FIG. 29 shows exemplary cross-sections of specimens including 0% Reduction profile, 25% Reduction profile, 50% Reduction profile, 75% Reduction profile, and 100% Reduction profile, according to aspect of the present disclosure. The 0% Reduction profile, 25% Reduction profile, 50% Reduction profile, and 75% Reduction profile represent 0%, 25%, 50%, and 75% of the maximum possible weight reduction (i.e., 100%), respectively. FIGs. 30A-30E show exemplary specimens including 0% Reduction profile, 25% Reduction profile, 50% Reduction profile, 75% Reduction profile, and 100% Reduction profile, respectively. Each specimen was manufactured using the system 1100 and was tested in 4-point bending to failure test, as previously described in Examples 2 and 3.

[0174] Flexural testing results are shown below in Table 7. FIGs. 31A-31E show graphs of load displacement of a neat beam and a HAAM beam corresponding to 0% Reduction profile, 25% Reduction profile, 50% Reduction profile, 75% Reduction profile, and 100% Reduction profile, respectively. These results demonstrate that the strength of the reduced cross-section beams was significantly higher than that of the neat beam. However, the beams corresponding to 50% and 100% Reduction profiles exhibited a different behavior, possibly indicating defects in the print.

Table 7. Flexural Testing Results.

[0175] The flexural strength results indicate that, with a significant amount of AM material removed, the addition of CFRTP reinforcement enables retention of a strength that is equivalent to a full-sized beam constructed using AM alone. Accordingly, the HAAM process may be utilized to lightweight LAAM structural components.

Example 5: Print Stability with an unsupported section

[0176] The present example demonstrates the ability of a CFRTP substrate including an unsupported section, to support overprinted LAAM material while avoiding collapse due to self-weight under overlying LAAM material and heat softening.

[0177] In this example, LAAM beams were overprinted on a CFRTP substrate including an unsupported section of varying length, using the system 1100, as described in Example 2. The varying length of the unsupported section of the CFRTP substrate included 3 inches, 7.5 inches, 15 inches, and 22.5 inches, corresponding to span to depth ratios of 1.0, 2.5, 5.0, and 7.5, respectively. Additionally, a specimen from the previous examples was included to represent a span to depth ratio of 0, corresponding to a fully supported specimen.

[0178] Finite Element Analysis (FEA) was performed to predict the behavior of the

CFRTP substrate as heat and weight are added during the printing process. The EFA model was intended to predict possible manufacturing risks using the HAAM process. In some embodiments, a FEA model is intended to inform future predictive methods, which may aid in designing the configuration of CFRTP reinforcement in more complex structures. FIG. 32 shows an exemplary FEA model of predicted deflection using a CFRTP substrate including an unsupported section, mid print, according to aspects of the present disclosure.

[0179] FIG. 33 shows a system 1200 to measure the deflection of a CFRTP substrate 1212 at the midspan of the unsupported section, according to aspects of the present disclosure. In some embodiments, the system 1200 includes two heated platens 1210, the CFRTP substrate panel 1212, and a string potentiometer 1214. The heated platens 1210 serve as supports, and vacuum hold-down the CFRTP substrate panel 1212. The heated platens 1210 are arranged such that the gap between them creates an unsupported length 1216. In some embodiments, adhesive-backed strip heaters are used to heat the unsupported section of the substrate panel 1212. In some embodiments, two separate closed-loop controllers are used to heat the CFRTP substrate panel 1212. For example, one controller operates the heated platens 1210, and one controller operates the adhesive strip heaters. The heated platens 1210, and the adhesive strip heaters are configured to maintain the same CFRTP top surface temperature (T2). In some embodiments, the system 1200 includes a plurality of thermocouples disposed on the CFRTP substrate 1212, and the heated platens 1210. The deflection of the CFRTP substrate 1210 at the midspan of the unsupported section was measured using the string potentiometer 1210.

[0180] FIG. 34 shows an exemplary system 1250 of overprinting on an unsupported CFRTP substrate 1212, according to aspects of the present embodiments. In some embodiments, the system 1250 includes two heated platens 1210, the CFRTP substrate panel 1212, and a 3D printer head 1252. FIG. 35 is an image of an exemplary final part manufactured by the system 1250, demonstrating a deformation due to the deflection of the unsupported section of the CFRTP substrate 1212.

[0181] To evaluate the quality of manufactured beams using the unsupported CFRTP substrate 1210, each specimen was tested in 4-point bending to failure test, as previously described in Examples 2 and 3. FIG. 36 shows graphs of load displacement for a neat beam, beams printed on an unsupported CFRTP substrate including span to depth ratios of 1, 2.5, 5, and 7.5, and a fully supported beam, according to aspects of the present disclosure. Each of the printed beams with an unsupported CFRTP exhibit stiffness and strength exceeding that of the neat beam (e.g., printed without an underlying CFTRP substrate). In addition, each of the printed beams with an unsupported CFRTP exhibit increased stiffness and strength compared to that of the fully supported beam. However, this highlights one difference between this example and the previous examples. Due to the resulting deformations seen in the beams manufactured with an unsupported CFRTP substrate (e.g., FIG. 36), it was not possible to trim the CFRTP substrate to match the size of the beam. As a result, these beams had a larger reinforcement area at the bottom compared to the beams tested previously. Accordingly, as the fully supported specimen data is taken from previous examples, these results are not a direct 1 : 1 comparison, but merely included for context.

[0182] Table 8 shows the flexural moment at failure for a neat beam, beams printed on an unsupported CFRTP substrate including span to depth ratios of 1, 2.5, 5, and 7.5, and a fully supported beam. These results demonstrate that, while the extent of the unsupported span affects the final strength of a beam, each beam exhibits a greater strength compared to that of the neat beam, or the beam printed on a fully supported CFRTP substrate.

Table 8. Flexural Testing Results.

[0183] This example demonstrates that a section of a CFRTP substrate can effectively serve as a substrate for LAAM to print overhang structures with minimal additional support. While some degree of deformation was observed during the process, the results indicate that a substantial span can be achieved without compromising the structural integrity of the final component. For example, the largest span that was tested exhibited significantly higher strength compared to an equivalent member manufactured without a CFRTP substrate. These findings suggest that integrating a CFRTP substrate as a supporting element in LAAM could enhance the feasibility of printing complex geometries while maintaining high mechanical performance.

Further Examples

[0184] FIG. 12 illustrates a 3D-printed structure 1000 with exemplary overhang angles 1002. Due to well-understood constraints of 3D printing (i.e., additive manufacturing), there is a limit to the overhang angle which can be achieved.

[0185] FIG. 13 illustrates a structure 1004 produced via HAAM, according to aspects of the present disclosure. The structure 1004 includes both a printed portion 1006 and a prefabricated portion 1008. The combination of the printed portion 1006 and the prefabricated portion 1008 can be used in connection with HAAM to achieve full 90-degree overhangs, as illustrated in FIG. 13. In some embodiments, robotic arms 1010 and other machines may be used in connection with the HAAM process.

[0186] FIG. 14 panels A-C show a die used for pultrusion (A), a pultruded part (B), and a post-pultrusion formed part (C), according to aspects of the present disclosure. The die in panel A may include a void 1012 shaped to match the desired geometry of a prefabricated part 1014 (for example, a pultruded prefabricated part 1014). As shown in panel B, the prefabricated part 1014 may include a first interlock feature 1016 along a first edge and a second interlock feature 1018 along a second edge. As shown in panel C, the prefabricated part may be further formed (i.e., post pultrusion, via one or more forming steps (for example, via incremental forming, i.e., using robotic arms 1010 and/or other forming machines)) to produce a formed prefabricated part 1020. Panel C shows that the postpultrusion (i.e., post fabrication) forming process may including bending one or both edges of the prefabricated part 1014 through one or more angles 1022 to form new geometries. [0187] FIG. 15 panels A-D show a portion of a HAAM part (A), powder metal infused layers (B), a cross-section of a column 1036 formed via HAAM (C), and a perspective view of a column 1036 formed via HAAM (D), according to aspects of the present disclosure. As shown in panel A, a HAAM part may include a printed portion 1006 and a prefabricated portion 1008. The prefabricated portion 1008 may include a geometry that is the result of, for example, a pultrusion process, as well as one or more post-pultrusion forming processes, as explained herein in connection with FIG. 14. The printed portion 1006 may include conventional additive layers 1030, as well as metal powder infused AM layers 1032, which may be used to increase inter-layer adhesion as well as intra-layer stiffness and/or elasticity (for example, to increase the tension resistance of the final HAAM part). Whereas panel A shows, for example, a quadrant of a HAAM part (i.e., a column produced via HAAM in this case), panel C shows a cross-section of four quadrants assembled together into a column 1036, including the printed portions 1006 and prefabricated portions 1008. Prefabricated portion 1008 may include interlock features 1024 as well as one or more connection features 1026 (for example, flanges, bolt holes, nuts, bolts, etc.) for joining multiple prefabricated portions 1008 together (for example, for joining together multiple of the quadrants shown in panel A (each quadrant including a printed portion 1006 and a prefabricated portion 1008)). Panel D shows a perspective view of a fully assembled column 1036 formed using the HAAM process.

[0188] FIG. 16 panels A-B show 3D renderings of columns 1036 formed via HAAM, according to aspects of the present disclosure. Each of the columns includes a printed portion 1006, a prefabricated portion 1008, and multiple interlock features 1024. [0189] FIG. 17 panels A-B show a cross-section of a beam 1038 formed via HAAM (A), and a perspective view of a beam 1038 formed via HAAM (B), according to aspects of the present disclosure. The beam may include a printed portion 1006, a prefabricated portion 1008, interlock features 1024, and/or connection features 1026, as described herein. Multiple melt lines are visible in FIG. 17 as well.

[0190] FIG. 18 illustrates a structure 1038 produced via HAAM, according to aspects of the present disclosure. In some embodiments, the structure may include a beam 1038, for example, similar to the beam shown in FIG. 17. The beam 1038 may include a prefabricated workpiece or assembly 1008, as well as an additively manufactured portion 1006, as described herein. In the embodiment of FIG. 18, the additively manufactured portion 1006 may be or include a composite structure and itself may include printed or embedded long fibers 1032 interspersed with shorter fibers (or print layers) 1030. For example, in some embodiments, the additively manufactured portion 1006 may include conventional additive layers 1030, as well as metal powder-infused AM layers 1032, which may be used to increase inter-layer adhesion, as well as intra-layer stiffness and/or elasticity (for example, to increase the tension resistance of the final HAAM part). In some embodiments, the additively manufactured portion 1006 may include long-fiber reinforced thermoplastic composites 1032 placed among shorter printed layers 1030 (for example, via the automated HAAM manufacturing system in connection with the system illustrated in FIG. 20) For example, long-fiber reinforced thermoplastic composites 1032 may be placed among shorter printed layers during a large-scale additive manufactured printing process.

[0191] FIG. 19 panels A and B illustrate structures produced via HAAM, according to aspects of the present disclosure. In some embodiments, the structures may include columns 1036 (panel B) or column components 1040 (panel A), as described herein in connection with FIGs. 15 and 16. In some embodiments, the columns 1036 and/or column components 1040 may include a prefabricated portion 1008, a printed portion 1006, conventional additive layers 1030, and/or metal powder-infused AM layers 1032. In some embodiments, the columns 1036 and/or column components 1040 may include embedded long fibers 1032 interspersed with shorter fibers (or print layers) 1030 in addition to (or instead of) the metal powder-infused AM layers 1032.

[0192] FIG. 20 illustrates an automated HAAM manufacturing system 1050, according to aspects of the present disclosure. In some embodiments, the automated HAAM manufacturing system 1050 includes one or more components for performing automated part integration 1052 and one or more components for placing or printing thermoplastic structural members 1054. In some embodiments, the automated HAAM manufacturing system 1050 includes a Large-Scale Additive Manufacturing (LSAM) system with an integrated fiber placement mechanism (for example, via one or more robotic arms and/or one or more spools) to integrate long-fiber reinforced thermoplastic composites, fibers, and/or components into LSAM printed parts during the printing process. By strategically placing fibers within a printed part during printing (for example, in high stress or high strain areas), the amount of material used during the print process may be able to be significantly reduced, while still maintaining the structural integrity of the final HAAM-produced part, as described herein.

[0193] Certain embodiments of the present disclosure were described above. It is, however, expressly noted that the present disclosure is not limited to those embodiments, but rather the intention is that additions and modifications to what was expressly described in the present disclosure are also included within the scope of the disclosure. Moreover, it is to be understood that the features of the various embodiments described in the present disclosure were not mutually exclusive and can exist in various combinations and permutations, even if such combinations or permutations were not made express, without departing from the spirit and scope of the disclosure. The disclosure has been described in detail with composite particular reference to certain embodiments thereof, but it will be understood that variations and modifications can be affected within the spirit and scope of the claimed invention.

Claims

1. A method comprising: prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece comprising a melt layer disposed on at least one bonding surface of the prefabricated workpiece (e.g., a top surface of a workpiece); disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system; applying heat to the at least one bonding surface and/or the melt layer; printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece comprising the prefabricated workpiece.

2. The method of claim 1, wherein printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system comprises forming a transition layer between the prefabricated portion of the workpiece and the 3D-printed portion of the workpiece.

3. The method of claim 2, wherein the transition layer comprises a thickness in a range from about 1pm to about 5pm.

4. The method of any one of the previous claims, wherein the method comprises determining (e.g., predicting) (e.g., prior to layer-by-layer printing) (e.g., by a processor of a computer (e.g., using FEA)) thermal distortion(s) of the printed portion of the workpiece and the prefabricated portion of the workpiece induced during the layer-by-layer printing of the printed portion of the workpiece.

5. The method of claim 4, wherein the determination of the thermal distort! on(s) comprises: conducting a heat transfer analysis of the workpiece and the prefabricated portion of the workpiece at a plurality of time points (e.g., at least two, at least three, at least four or more) during the layer-by-layer printing process; and determining a plurality of nodal temperatures.

6. The method of claim 5, wherein the method comprises performing a structural analysis of the workpiece and the prefabricated portion of the workpiece at the plurality of time points based on, at least, the plurality of nodal temperature.

7. The method of any one of claims 4-6, wherein the method comprises mitigating (e.g., by heating, cooling, modifying a tool path, etc.) the determined thermal distortions.

8. The method of any one of claims 4-7, wherein the thermal distortion(s) comprises thermal strain and/or thermal stress.

9. The method of any one of the previous claims, wherein the method comprises cooling portions of prefabricated workpiece adjacent to and/or disposed beneath the melt layer.

10. The method of any one of the previous claims, wherein the method comprises determining (e.g., predicting) (e.g., prior to layer-by-layer printing) (e.g., by a processor of a computer (e.g., using finite element analysis (FEA))) mechanical distortion(s) of the printed portion of the workpiece and the prefabricated portion of the workpiece induced during the layer-by-layer printing of the printed portion of the workpiece.

11. The method of claim 10, wherein the determination of the mechanical distort! on(s) comprises conducting an analysis of the workpiece and the prefabricated portion of the workpiece at a plurality of time points (e.g., at least two, at least three, at least four or more) during the layer-by-layer printing process.

12. The method of claim 11, wherein the method comprises performing a structural analysis of the workpiece and the prefabricated portion of the workpiece at the plurality of time points.

13. The method of any one of claims 10-12, wherein the method comprises mitigating (e.g., by heating, cooling, modifying a tool path, etc.) the determined mechanical distortions.

14. The method of any one of claims 1-13, the method comprising prefabricating the prefabricated workpiece using one or more of the following techniques: investment casting, injection molding, forging, composite manufacturing, continuous forming (e.g., via a continuous forming machine (CFM)), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, and machining.

15. The method of any one of claims 1-14, the method comprising prefabricating the prefabricated portion using one or more of the following techniques: composite manufacturing, polymer matrix composites (PMC) manufacturing, metal matrix composites (MMC) manufacturing, and carbon matrix composites (CMC) manufacturing.

16. The method of any one of claims 1-15, wherein the melt layer comprises a thickness of about 200pm or less (e.g., 175pm or less, 150pm or less, e.g., from about 10pm to about 200pm, from about 25pm to about 150pm, and/or from about 50pm to about 100 pm).

17. The method of any one of claims 1-16, wherein the method comprises heating the prefabricated workpiece (e.g., a surface of the prefabricated workpiece) to a temperature from about 150°C to about 314°C.

18. The method of any one of claims 1-16, wherein the method comprises heating the prefabricated workpiece to about 400°C or less (e.g., 314°C or less, 150°C or less).

19. The method of any one of claims 1-16, wherein the prefabricated workpiece is substantially at room temperature.

20. The method of any one of claims 1-17, wherein the additive manufacturing system comprises a nozzle for deposition of the printing material and heating the printing material to a temperature about 400°C or less (e.g., 257°C or less).

21. The method of any one of claims 1-17, wherein the additive manufacturing system comprises a nozzle for deposition of the printing material and heating the printing material to a temperature from about 85°C to about 257°C.

22. The method of any one of claims 1-17, wherein the prefabricated workpiece comprises one or more thermoplastics.

23. The method of any one of claims 1-18, wherein the prefabricated workpiece comprises polyethylene terephthalate glycolpolycarbonate (PETG), polyethylene (e.g., high- density polyethylene (HDPE), e.g., low-density polyethylene (LDPE)), polypropylene (PP), poly etheretherketone, polyaryletherketone (e.g., low melt polyaryletherketone), polyamide (e.g., nylon 6, nylon 6 6, nylon 6 12, nylon 4,6 nylon 12, polyamide 12 (PA12), etc.), acrylonitrile butadiene styrene (ABS), polylactic acid (PL A), polyvinylchloride (PVC), polycarbonate (PC), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), poly(methyl methacrylate) (PMMA), polyetherimide (PEI), polybenzimidazole (PBI), or any combination thereof.

24. The method of any one of claims 1-23, wherein the prefabricated workpiece and/or the printing material comprises glass fibers (e.g., E-glass), carbon fibers, aramid fibers, basalt fibers, organic fibers (e.g., hemp fibers, e.g., wood-derived fibers), or any combination thereof.

25. The method of any one of claims 1-24, wherein the method comprises placing (e.g., using an automated system) a reinforcing component within the printed portion of the workpiece during layer-by-layer printing.

26. The method of claim 25, wherein the method comprises use of a multi-axis 3D printer to deposit the printing material around the reinforcing component.

27. A hybrid workpiece comprising: a prefabricated portion; and a 3D printed portion, wherein the prefabricated portion is melt-bonded to the 3D printed portion, thereby forming the hybrid workpiece as a unitary structure, wherein the prefabricated portion comprises a composite structure comprising at least one fiber embedded within a matrix, and wherein the 3D printed portion is formed via a continuous, layer-by-layer build process.

28. The hybrid workpiece of claim 27, wherein the 3D printed portion comprises one or more reinforcing components.

29. The hybrid workpiece of claims 27 or 28, wherein both the prefabricated portion and the 3D printed portion comprise materials from the same class of materials as that of a melt layer disposed between the portions.

30. The hybrid workpiece of any one of claims 27-29, wherein the prefabricated portion is formed using one or more of the following techniques: investment casting, injection molding, forging, composite manufacturing, continuous forming (e.g., via a continuous forming machine (CFM)), pultrusion, extrusion, thermoforming, compression molding, continuous compression molding, stamp forming, and machining.

31. The hybrid workpiece of any one of claims 27-30, wherein the at least one fiber embedded within a matrix is a glass fiber (e.g., E-glass), a carbon fiber, an aramid fiber, a basalt fiber, or an organic fiber (e.g., hemp fibers, e.g., wood-derived fibers).

32. The hybrid workpiece of any one of claims 27-31, wherein the matrix comprises polyethylene terephthalate glycolpolycarbonate (PETG), polyethylene (e.g., high-density polyethylene (HDPE), e.g., low-density polyethylene (LDPE)), polypropylene (PP), poly etheretherketone, polyaryletherketone (e.g., low melt polyaryletherketone), polyamide (e.g., nylon 6, nylon 6 6, nylon 6 12, nylon 4,6 nylon 12, polyamide 12 (PA12), etc.), acrylonitrile butadiene styrene (ABS), polylactic acid (PA), polyvinylchloride (PVC), polyethylene terephthalate (PET), acrylonitrile styrene acrylate (ASA), poly(methyl methacrylate) (PMMA), polyetherimide (PEI), polybenzimidazole (PBI), or any combination thereof.

33. The hybrid workpiece of any one of claims 29-32, wherein the melt layer comprises a thickness of about 200pm or less (e.g., 175pm or less, 150pm or less, e.g., from about 10pm to about 200pm, from about 25pm to about 150pm, from about 50pm to about 100 pm).

34. A method (e.g., of identifying thermal and/or mechanical distortions in a composite 3D printed part) comprising: determining (e.g., by a processor of a computer (e.g., using FEA)) thermal and/or mechanical distortion(s) (e.g., thermal stresses and/or strains, mechanical stresses and/or strains) of a hybrid workpiece comprising a prefabricated portion and a 3D printed portion created by layer-by-layer deposition of a material (e.g., a heated material) using an additive manufacturing system; identifying (e.g., by the processor) thermal and/or mechanical distortion(s) of the workpiece induced by the layer-by-layer deposition of the material (e.g., the heated material), wherein the thermal and/or mechanical distortion(s) are beyond a predetermined threshold level; modifying (e.g., by the processor) at least one layer-by-layer deposition parameter to reduce the thermal and/or mechanical distortion(s) induced on the prefabricated workpiece.

35. The method of claim 34, wherein the material is a heated material.

36. The method of claim 35, wherein determining the thermal distortion(s) is based on, at least, one or more parameters for layer-by-layer deposition of the heated material by an additive manufacturing system.

37. The method of claims 35 or 36, wherein the method comprises identifying a plurality of temperatures of the hybrid workpiece (e.g., using an infrared camera, predictively generating the temperatures) at a plurality of timepoints and locations within the hybrid workpiece during the layer-by-layer deposition of the heated material onto the hybrid workpiece.

38. The method of claim 37, wherein the method comprises identifying the thermal distortion(s) using a structural analysis based on, at least, the shape of the hybrid workpiece and the plurality of temperatures.

39. The method of any one of claims 35-37, wherein the at least one deposition parameters comprise at least one of the following deposition parameters: a temperature of the prefabricated workpiece, a path of a tool used in layer-by-layer deposition, a hybrid workpiece cooling rate, and a speed of layer-by-layer deposition.

40. The method of claim 1, wherein printing, layer by layer, comprises raising a temperature of the printing material.

41. The method of claim 39, wherein printing, layer by layer, comprises raising a temperature of the printing material to within a melting temperature range of the printing material.

42. The method of claim 1, wherein material of the same class of materials comprises material from one of the following classes of materials: polycarbonates (PC), polypropylenes (PP), polyethylene terephthalate glycolpolycarbonates (PETG), polyethylene materials (PE), acrylonitrile butadiene styrene (ABS) materials, polylactic acids, polyvinylchlorides (PVC), and polyamide 12.

43. A method comprising: prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece comprising a melt layer disposed on at least one bonding surface of the prefabricated workpiece; disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system; heating the at least one bonding surface to glass transition temperature of the melt layer; printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece comprising the prefabricated workpiece.

44. A method compri sing : prefabricating a portion of a workpiece, thereby forming a prefabricated workpiece, the prefabricated workpiece comprising a melt layer disposed on at least one bonding surface of the prefabricated workpiece (e.g., a top surface of a workpiece); disposing the prefabricated workpiece within an additive manufacturing build area of an additive manufacturing system, wherein the prefabricated workpiece is partially supported; applying heat to the at least one bonding surface and/or the melt layer; printing, layer-by-layer, on top of at least one bonding surface via the additive manufacturing system using a material of the same class of materials as that of the melt layer, thereby forming a printed portion of the workpiece that is unitary with a prefabricated portion of the workpiece comprising the prefabricated workpiece.

45. The method of claim 44, wherein the printed portion is or comprises an overhang.

46. A hybrid workpiece comprising: a prefabricated portion; and a 3D printed portion, wherein the prefabricated portion is partially supported, wherein the prefabricated portion is melt-bonded to the 3D printed portion, thereby forming the hybrid workpiece as a unitary structure, wherein the prefabricated portion comprises a composite structure comprising at least one fiber embedded within a matrix, and wherein the 3D printed portion is formed via a continuous, layer-by-layer build process.

47. The hybrid workpiece of claim 46, wherein the 3D printed portion is or comprises an overhang.

48. A method (e.g., of light weighting a composite 3D printed part) comprising: determining (e.g., by a processor of a computer (e.g., using FEA)) thermal and/or mechanical distortion(s) of a hybrid workpiece comprising a prefabricated portion and a 3D printed portion created by layer-by-layer deposition of a material (e.g., a heated material) using an additive manufacturing system; reducing (e.g., by the processor) a cross-section of the hybrid workpiece; identifying (e.g., by the processor) thermal and/or mechanical distortion(s) of the workpiece induced by the layer-by-layer deposition of the material (e.g., the heated material); adjusting (e.g., by the processor) the cross-section of the hybrid workpiece to achieve a predetermined threshold level for the thermal and/or mechanical distortion(s).