FR3039489A1 - RAILWAY CHASSIS - Google Patents

Abstract

The object of the invention is a railway-type lower vehicle-type composite chassis comprising a sandwich material bottom comprising two skins separated by a first polymer foam core, characterized in that the sandwich material produces the bottom and the bottom of the faces. of the vehicle and is covered on one of its skins called lower skin for making the outer face of the vehicle frame of a second foam core coated with a Kevlar fabric forming shockproof protection.

Description

RAILWAY CHASSIS

Field of the invention

The present invention is in the transport sector in general and the railway in particular and for all segments concerned: high-speed trains, regional trains or urban rail transport vehicles and the various train chassis architectures.

It relates to the production of structures made of composite materials so as to make it possible to lighten the structures of the vehicles at a lower cost. As in any transport field, the lightening of the structures allows the use of a lower consumption of energy, which is of interest both economically and ecologically.

The present invention relates even more particularly to the manner of producing a composite material frame of a vehicle while taking into account its use constraints.

The railway reference structure has always been, and still is today, a structure made of metallic, steel or aluminum materials.

Technological background

Figure 1 gives a more detailed example of realization of a railway transport vehicle here floor with metal frame 1.

The chassis comprises a flat central part 2 which constitutes the bottom of the chassis, comprising crosspieces 3. According to FIG. 2, the bottom comprises a protective plate 4a, a support plate of the interior equipment 4b and comprises two upward longitudinal longitudinal structures 5a, 5b in the form of self-stiffened structures, which are connected to the self-stiffened faces 7a, 7b by connecting elements 6a, 6b or stretchers.

The connecting elements 6a, 6b on the edges of the frame provide resistance to longitudinal bending and the junction with the side faces. The sleepers 3 provide resistance to transverse flexion.

The chassis of a railway vehicle is located at the bottom and is therefore potentially subject to projections from the ballast.

In the above example, the bottom and the side structures are coated with a thick layer of an elastomer for protection against shock ballast.

The protective sheet 4a contributes to the overall rigidity due to its thickness and also contributes to the robustness to ballast shocks.

Ballast shocks are defined in France according to standard NF 07101, which defines the test and shock conditions to be taken into account for train chassis design. For example, it says that one must consider the projection of objects of 60 grams striking the structure of the frame. Moreover, an incidence between 0 and 35 ° relative to the normal to the surface, and an energy that can vary from 12 to 285J must be taken into account. The standard also defines different classes of results based on the energies and impacts of the projections.

These specifications are defined in an envelope that encompasses situations that are not all realistic. For example, in the case of a train running at high speed, if the energy of a ballast pebble can be very large, its incidence relative to the normal to the surface will be closer to 90 °.

Finally, with respect to the shock resistance of the frame of the present invention energy of 60 Joules with an incidence of 45 ° was retained.

Shocks up to 60J are low energy shocks, which can induce local plastic deformations in the case of metallic materials and, in the case of composite materials, local delamination.

The protection of composite materials against such shocks is not usually carried out permanently on structural parts. On the other hand, traditionally in composite structures, the possibility of detecting shocks is ensured, and structures made of composite materials are designed and dimensioned so that they can continue to be used despite the presence of defects caused by shocks. .

Where this is not possible, solutions exist to protect the composite materials by protective layers comprising a deformable foam material coated with a metal sheet. Such a solution is known in particular from document FR 2 933 331 A1 and applies to impact energies up to a hundred Joules.

For much larger energies, it falls in the field of shielding typically vis-à-vis the projectiles, where the solutions are either based on much thicker metal materials, or use aramid polymer fabrics known under the brand Kevlar including possibly associated with ceramics. The shields are adapted to protect object impact structures having speeds of up to several hundred m / s.

BRIEF DESCRIPTION OF THE INVENTION The invention therefore aims to design a lighter railway chassis composite material compatible with the risk of shock ballast and remains simple to achieve and thin.

To do this, the present invention provides a rail-type vehicle lower composite chassis comprising a sandwich material bottom comprising two skins separated by a first polymer foam core, characterized in that the sandwich material produces the bottom and the bottom of the faces. of the vehicle and is covered on one of its skins called lower skin for making the outer face of the vehicle frame of a second foam core coated with a Kevlar fabric forming shockproof protection.

The skins are advantageously continuous from one end of the face to the other.

The frame advantageously comprises fixing elements integrated in the sandwich material.

The prepreg is preferably made of two folds of fiber fabrics oriented at 0 ° and 90 ° ± 5 °.

The folds at 0 ° and 90 ° are in particular in a ratio balanced from 45/55% to 55/45%. The total thickness of the skin as a function of the stresses encountered is preferably 1.2 mm ± 0.1 mm.

According to a first embodiment, the fabric of the impact protection consists of a prepreg of aramid polymer fibers impregnated with an epoxy resin.

According to an alternative embodiment, the fabric of the anti-shock protection consists of a pre-impregnated glass fabric impregnated with an epoxy resin.

The second core of the impact protection is advantageously a PET foam of 80 kg / m3 ± 20 kg / m3 or a PMI foam of 60 kg / m3 ± 20 kg / m3, of thickness 8 mm ± 2 mm, itself bonded to the lower skin of the sandwich material.

The skins advantageously comprise 3/7 ± 5% fibers at 0 ° ± 5 °, 2/7 ± 5% fibers at 90 ° ± 5 °, 2/7 ± 5% fibers at +/- 45 ° ± 5 °.

The skins of the sandwich material are preferably carbon fibers.

According to the example, the skins are of a thickness of 4 mm ± 0.4 mm. for the application in question, the first core advantageously has a thickness of 55 mm ± 1 mm.

The first core is advantageously made of PET foam or aluminum honeycomb density of 100Kg / m3 ± 20 Kg / m3.

BRIEF DESCRIPTION OF THE DRAWINGS Other characteristics and advantages of the invention will become apparent on reading the following description of a nonlimiting exemplary embodiment of the invention with reference to the drawings which represent:

In Figure 1: a longitudinal sectional view of a railcar with a metal chassis of the prior art;

In Figure 2: a cross-sectional view of the lower part of a car having a lower structure of the prior art;

In Figure 3: a perspective view of a lower car chassis according to one embodiment of the invention;

In Figure 4: a cross-sectional view of the lower part of a car comprising a lower frame according to the invention;

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention consists of a composite chassis architecture, supplemented with a solution for protection against ballast shocks.

Figure 3 is a general view of a frame 10 of composite material in sandwich form. The chassis is typically monobloc along the entire length of the vehicle body and includes the bottom 11 and the bottom of the faces 12. Connecting elements distributed over the entire periphery of the chassis, but not shown serve to fix the chassis to the vehicle.

According to Figure 4, the frame is made of sandwich material comprising two skins 13, 14 separated by a first foam core 15 to ensure the structural strength of the frame. This solution covers the entire chassis, side structures and bottom.

The protection against the ballast comprises a second foam 16 coated with a fabric 17 made of aramid polymer. According to the example shown the protection rises on the sides of the chassis making the bottom of the vehicle faces.

It should be noted that the chassis comprises fixing elements necessary for interior equipment such as seats 22 and false floors 23 in the form of tubular sections 18, 19, 20, 21, in particular carbon tubes integrated in the sandwich along the length of the chassis. .

The dimensioning elements (thicknesses of the core, skins, quantities and orientation of the fibers, nature of the skin core) of the sandwich are determined according to the rules of the art according to the constraints that the vehicle must undergo according to conventional methods of sizing materials. For a high-speed train type car with two levels of 20 m length, skins with a thickness of 4 +/- 0,4 mm will be chosen which include: 3/7 fibers +/- 5% at 0 ° +/- 5 °, 2/7 fibers +/- 5% at 90 ° +/- 5 °, 2/7 fibers +/- 5% at +/- 45 ° +/- 5.

The fibers may then be high-strength carbon fibers, for example of T700 type from the company Toray. The core has a thickness of 55 +/- 1 mm, it is made either of polyethylene terephthalate foam or polyethylene terephthalate PET closed cell density of 100Kg / m3 ± 20 Kg / m3 or nest aluminum bee. The impact protection comprises an outer layer 17 made either of aramid fabric made with a pre-impregnated aramid polymer fibers known in particular under the trademark Kevlar, 29 impregnated with an epoxy resin or with a preimpregnated glass fabric itself. The prepreg consists of two tissue plies balanced 0/90 ° ± 5 ° in a ratio of 45/55% to 55/45%, for a total thickness of 1.2 ± 0.1 mm.

To complete the shock protection, the folds are based on a foam 16 PET 80 +/- 20Kg / m3, 8 +/- 2mm thick, itself glued to the lower skin of the structural sandwich.

Beams 24, on which are taken the internal fittings 26 of the box forming with the skin 14 of the ventilation ducts and the backs of the seats 22, are fixed to the tubular sections 20, 21 on the bottom faces.

Support legs or longitudinal sections 25 are fixed on the tubular sections 18, 19 of the bottom. These supporting or profiled legs 25 support the false floor 23 and uprights 26 on which are fixed the seats of the seats 22. The space between the false floor 23 and the inner skin 14 can serve as a passage for conduits 27 of electric cables or other.

From the process point of view, the assembly is made by co-molding the composite material and its protection.

We can adapt the range of manufacture according to the particular cases, following the rules of the art. The manufacture of the frame can in particular be carried out according to the following process: - Realization of a female mold representing the entire frame with ballast protection, this mold having a surface state to ensure the quality of the outer surface of the frame. - Preparation of the mold according to known methods and in particular cleaning the mold and setting up a suitable mold release product,

Then, the manufacture is started by the shock-proofing part by the lay-up of the folds of the shockproof protective fabric, pre-impregnation with a roller;

The impact protection foam is placed in place and then a film of adhesive is deposited on this foam, for example a supported film of adhesive, that is to say a film of adhesive deposited on a weft, as known in the art. in the field of composites, for example of the R 1035 type from Structil.

The outer skin of the structure is then draped and the resin is polymerized under vacuum at 120 ° C. for 5 hours.

After polymerization, without demolding interoperability, the stack is continued with the structural part:

We proceed to the establishment of a second glue film, for example a traditional adhesive for the production of composite panels on the external skin of the structure, the implementation of the foam of the structural sandwich, including the necessary inserts. to fixations.

Then, we proceed to the establishment of a third glue film suitable for the production of composite panels and is put in place the second skin for making the inner face of the chassis car by draping.

Once the assembly is assembled, the resin is polymerized under vacuum at 120 ° C. for 5 hours as before.

The manufacture continues with demolding, then finishes such as deburring, machining, installation of fasteners as necessary. The invention is not limited to the example shown and in particular the lower faces may comprise other cuts than door cuts as shown in FIG.

Claims (12)

1 - Railway-type lower composite vehicle chassis having a sandwich material bottom comprising two skins separated by a first polymer foam core, characterized in that the sandwich material forms the bottom and the bottom of the vehicle faces and is covered on the inside surface. one of its skins called lower skin for making the outer face of the vehicle frame of a second foam core coated with a Kevlar fabric forming shockproof protection. 2 - Composite frame according to claim 1 wherein the skins are continuous from one end of the face to the other. 3 - composite frame according to claim 1 or 2 for which the frame comprises fasteners integrated in the sandwich material. 4 - Composite frame according to any one of the preceding claims wherein the prepreg consists of two folds of fiber fabrics oriented at 0 ° and 90 ° ± 5 ° in a balanced ratio of 45/55% to 55 / 45% for a total thickness of 1.2 mm ± 0.1 mm. 5 - Composite frame according to any one of claims 1 to 4 wherein the fabric of the impact protection consists of an aramid polymer impregnated fiber prepreg impregnated with an epoxy resin. 6 - Composite frame according to any one of claims 1 to 4 wherein the fabric of the impact protection consists of a pre-impregnated glass fabrics impregnated with an epoxy resin. 7 - Composite frame according to any one of the preceding claims wherein the second core of the impact protection is a PET foam of 80 kg / m3 ± 20 kg / m3 or a foam PMI of 60 kg / m3 ± 20 kg / m3, thickness 8 mm ± 2 mm, itself glued to the lower skin of the sandwich material. 8 - Composite frame according to any one of the preceding claims wherein the skins comprise 3/7 ± 5% of fibers at 0 ° ± 5 °, 2/7 ± 5% of fibers at 90 ° ± 5 °, 2/7 ± 5% fiber at +/- 45 ° ± 5 °. 9 - Composite frame according to any one of the preceding claims wherein the skins are carbon fiber. 10 - Composite frame according to any one of the preceding claims wherein the skins have a thickness of 4 mm ± 0.4 mm. 11 - Composite frame according to any one of the preceding claims wherein the first core has a thickness of 55 mm ± 1 mm. 12 - Composite frame according to any one of the preceding claims wherein the first core is made of PET foam or honeycomb density of 100Kg / m3 ± 20 Kg / m3.