CN115465458B - Baffle assembly capable of improving bird strike resistance of aircraft nose end frame - Google Patents
Baffle assembly capable of improving bird strike resistance of aircraft nose end frameInfo
- Publication number
- CN115465458B CN115465458B CN202211067348.3A CN202211067348A CN115465458B CN 115465458 B CN115465458 B CN 115465458B CN 202211067348 A CN202211067348 A CN 202211067348A CN 115465458 B CN115465458 B CN 115465458B
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- end frame
- baffle
- corner pieces
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- panel
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D45/00—Aircraft indicators or protectors not otherwise provided for
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64D—EQUIPMENT FOR FITTING IN OR TO AIRCRAFT; FLIGHT SUITS; PARACHUTES; ARRANGEMENT OR MOUNTING OF POWER PLANTS OR PROPULSION TRANSMISSIONS IN AIRCRAFT
- B64D45/00—Aircraft indicators or protectors not otherwise provided for
- B64D2045/0095—Devices specially adapted to avoid bird strike
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/40—Weight reduction
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- Engineering & Computer Science (AREA)
- Aviation & Aerospace Engineering (AREA)
- Vibration Dampers (AREA)
Abstract
A baffle assembly capable of improving bird strike resistance of an aircraft nose end frame comprises five supporting beams with cross sections in a shape like a Chinese character 'ji' and eight corner pieces with cross sections in a shape like a Chinese character 'ji' which are riveted on an aircraft end frame panel, and rivets are respectively fixed on an end frame main beam. A baffle plate composed of an upper panel made of 2024-T3 aluminum alloy, a lower panel made of 7075-T6 aluminum alloy and an aluminum foam core material is arranged on the upper surface of the supporting beam. In the invention, the reasonable sandwich structure plays a key role in bird strike resistance of the baffle, improves bird strike resistance of the aircraft nose, reduces structure weight and manufacturing cost. The test sample proves that under the condition that 1.8kg of bird bodies are impacted at the speed of below 200m/s, the baffle plate effectively utilizes the energy absorption effect of the foamed aluminum stress platform section generated when the aluminum foam bears compressive load, so that the acting force of bird body tissues is dispersed, the bird body tissues are prevented from penetrating through the lower panel, and the structural weight is effectively reduced on the premise that the bird strike resistance performance is maintained and meanwhile enough rigidity is possessed.
Description
Technical Field
The invention relates to the field of aircraft structural design, in particular to a baffle capable of improving bird strike resistance of an aircraft nose end frame and reducing weight and a support piece thereof.
Background
Bird strike accidents are accidents that occur when flying aircrafts such as aircrafts collide with flying birds. With the rapid development of civil aviation industry, civil aircraft bird strike accidents become one of the most serious security threats for civil aviation. The U.S. civil aviation report showed that, in 1990 through 2008, 89727 animals were reported to collide with a civil aviation aircraft, 97.4% of which were caused by birds. The relevant data show that the windward side of an aircraft, including the aircraft windshields, radomes, engines, wing leading edges and tail leading edges, are the most vulnerable sites to bird strikes. Various electronic devices and control circuits are arranged behind the inner end frame of the aircraft nose radome, and once the inner facilities are damaged by bird strike, catastrophic accidents are difficult to avoid. Therefore, the problem of bird strike resistance of the aircraft nose end frame is solved. The first clear rule in the "standards for airworthiness for transportation aircraft" set by the national aviation administration, 25.571 (e), for each structural part that may cause catastrophic damage, the aircraft must be able to successfully complete this flight at various heights from sea level to 2450m, under the impact of a bird of 1.8kg at Vc speed. Research shows that under high-speed collision, bird body shows obvious hydrodynamic behavior, because the aircraft nose radome adopts the honeycomb sandwich structure of thin-layer glass fiber paper at present, the high-speed bird body can pierce the radome easily and only loses about 5% kinetic energy, therefore, when the aircraft nose region is designed structurally, in order to satisfy the anti-bird collision requirement, the anti-bird collision baffle plate assembly is added on the end frame structure in the aircraft nose radar cabin, the baffle plate (figure 1) is formed by aluminum plate 1 and reinforcing rib 2 manufactured by milling 7075-T6 aluminum alloy, the baffle plate is connected with I-shaped support 3 and riveted with aircraft nose end frame girder 4, but the excessive weight gain of the baffle plate assembly is unfavorable for improving the economy of the aircraft.
Compared with the traditional aluminum honeycomb, the foamed aluminum material overcomes the defects of the aluminum honeycomb material such as simple structure, anisotropy, higher cost and other functions. In addition, aluminum honeycomb has poor plasticity, and many plate types cannot be processed by using aluminum honeycomb. The foamed aluminum is one of the most ideal materials for energy absorption and anti-collision effects in the current industrial materials, the energy absorption density reaches 4-20J/cm 3, and the foamed aluminum has a wide and flat stress platform, so that energy absorption can be continuously carried out in the whole compression process. In the field of high-strength anti-collision buffering, the anti-collision buffer has irreplaceable superior performance. Foam aluminum materials have been used for landing buffers for the return cabins of the Shenzhou airship series, landing buffers for the moon rover, and the like. Research shows that the foamed aluminum and high-strength steel, special ceramics, aramid fiber boards and other high-strength materials form a novel composite armor, and the energy absorption effect of the foamed aluminum is utilized to disperse the acting force of the armor piercing bullet and the armor breaking bullet, prevent the armor piercing bullet from entering the armor piercing bullet and the armor breaking bullet, and effectively reduce the structural weight while maintaining high protective performance. Therefore, the foamed aluminum material has great application potential in the design of bird strike resistant structures, and the structural weight is further optimized and reduced under the same bird strike resistant performance. However, some key problems in the application of the aluminum foam material in the head end frame bird strike resistant structure are not solved, for example, the bird strike resistant performance of the sandwich structure is closely related to the layer thickness ratio of each layer and the grade of the aluminum alloy material taken by the upper panel and the lower panel under the high-speed impact action of the bird, and the aluminum panel can be rapidly torn or collapse due to insufficient rigidity under the high-speed impact load by an unsuitable baffle, so that the impact resistance and the energy absorption effect of the sandwich structure are obviously affected. In addition, the support piece between the anti-collision baffle plate and the end frame main beam also obviously influences the anti-bird collision effect of the baffle plate, the C-shaped support or the I-shaped support is commonly used at present, and under the action of high-speed impact load, the lower panel is extremely easy to shear and damage at the C-shaped support and the I-shaped support, so that the anti-collision structure is invalid. In summary, there is also a great amount of space for optimizing the application of the aluminum foam sandwich structure to the bird strike resistance of the nose end frame, and there is a need for improved designs of the baffle assembly and support structure to improve bird strike resistance and reduce aircraft structural weight.
The Li Yulong professor and team of the university of northwest industry have long engaged in the study of aircraft bird strike resistance and have achieved corresponding results. The focus of these research works is to improve the bird strike resistance of the front edge of the plane and the bird strike resistance of the tail wing of the plane, for example, in the invention of publication No. CN102030102a, a bird strike resistant front edge of the plane is disclosed, in the invention of publication No. CN102390520a, a tail wing capable of improving the bird strike resistance of the plane is disclosed, in the bird strike resistant design of the tail wing structure of the plane, a design concept of bird energy dispersion is adopted, and by setting a double inclined plate with a reasonable angle, when the tail wing is impacted by a high-speed bird body, the skin can be deformed and attached to the double inclined plate in a proper amount, so that the bird body can slide along the outer side of the double inclined plate, and most of impact energy is dispersed, so that the bird strike resistance of the structure is improved.
For the aircraft nose structure, because the existence of radar can't set up similar energy in the radome and dredge the structure, the present stage adopts 7075 to add the muscle baffle and directly keeps out the bird body and assaults, therefore the weight gain is more. Therefore, the invention provides a novel bird strike resistant baffle and components thereof based on the concept of buffering the impact energy of a bird body by using a metal foam material.
The invention of CN108099281A discloses a composite material anti-bird strike baffle for aircraft nose. The baffle is composed of a dental plate 12 and a composite plate 13, the dental plate 12 being located outside the composite plate 13. Protrusions are distributed on the surface of the dental plate 12, so that birds can break up bones of birds and disperse impact force after striking, the size is reduced, and maintainability of the radome is improved. The composite plate 13 in the baffle adopts an aluminum honeycomb sandwich structure. However, aluminum honeycomb has poor plasticity, and many plate types cannot be processed by using aluminum honeycomb. Meanwhile, the invention also does not consider the problem of supporting connection between the baffle and the head end frame. At present, a C-shaped or I-shaped support is commonly used, and under the action of high-speed impact load, the lower panel is extremely easy to shear and damage at the C-shaped and I-shaped support, so that the anti-collision structure is invalid.
Hanssen, paper "Anumerical model for bird strike of aluminium foam-based SANDWICH PANELS" (journal International Journal of IMPACT ENGINEERING, 2006) proposes a sandwich baffle. The upper panel and the lower panel of the sandwich baffle are made of AA2024T3 aluminum alloy, the core material is made of aluminum foam, and the structure has good bird strike resistance through simulation. However, the upper panel and the lower panel are made of the same aluminum alloy material, the thickness of the upper panel and the lower panel is 1.66mm, the AA2024T3 aluminum alloy plates are adhered to two sides of the core material, the rigidity of the lower panel is insufficient when the upper panel and the lower panel bear impact load of a bird body, the risk of tearing and breaking occurs, the thicknesses of the upper panel, the lower panel and the core material are not optimized, and the supporting structure is not improved. Li Yulong et al in "bird strike value analysis of honeycomb sandwich radome structure" (explosion and impact, 2009) conducted numerical analysis on the process of striking a honeycomb sandwich radome by birds using nonlinear dynamics finite element software PAM-CRASH, and the result shows that the honeycomb sandwich radome cannot resist high-speed bird strike, so that a bird strike-resistant baffle must be arranged in the radome to meet the aircraft airworthiness authentication requirements. Li Yulong et al, in the "bird strike resistance analysis and design of certain sandwich structures" (aviation journal, 2012), used a multilayer honeycomb sandwich structure for the optimal design of a baffle in an aircraft, and filled a rigid foam material behind the baffle, but the baffle support structure was not improved, and the weight of the structure was increased more.
Disclosure of Invention
In order to overcome the defects of overhigh weight and unreasonable baffle support design of the bird strike resistant structure in the prior art, the invention provides a baffle assembly capable of improving bird strike resistant performance of an aircraft nose end frame.
The invention comprises a baffle, five supporting beams and eight corner pieces. Five supporting beams and eight corner pieces in the baffle assembly are riveted on the aircraft end frame panel, and the rivets are respectively fixed on the end frame main beam. Specifically, five support beams are distributed along the width direction of the end frame main beam, and are parallel to the length direction of the end frame main beam, and the distance between the central lines of the adjacent support beams in the width direction is 170mm. The eight corner pieces are divided into three groups according to numbers of 3, 2 and 3, the three groups of corner pieces are positioned on the surface of the aircraft end frame panel, two groups of 3 corner pieces are respectively positioned at two ends of the aircraft end frame panel, and one group of 2 corner pieces is positioned in the middle of the aircraft end frame panel. The distance between the central lines of the width direction of the adjacent two groups of corner pieces is 340mm, and the distance between the geometric centers of the adjacent two corner pieces in each group of corner pieces is 340mm
The baffle is arranged on the upper surface of the supporting beam, and the baffle and the supporting beam are in a natural contact state.
The baffle comprises an upper panel, a lower panel and an aluminum foam core material, wherein the aluminum foam core material is adhered between the upper panel and the lower panel to form a sandwich structure.
The length and the width of the baffle plate assembly are determined according to the size of the inner cavity of the aircraft nose end frame and are slightly smaller than the inner cavity of the aircraft nose end frame. And a reserved radar mounting port is formed on one long edge of the upper panel.
The upper panel is made of 2024-T3 aluminum alloy and has a thickness of 1.5mm. The lower panel is made of 7075-T6 aluminum alloy and has a thickness of 1mm. The aluminum foam has an aluminum density of 300kg/m 3 and a thickness of 15mm.
The cross sections of the five supporting beams are all in a shape like a Chinese character 'ji', and are made of 7075-T6 aluminum alloy materials, and the thickness of the five supporting beams is 2mm. The turning parts of the supporting beams are transited by circular arcs with the radius of 3 mm. The length and the width of the five supporting beams are matched with the size of the baffle.
The cross sections of the eight corner pieces are all in a shape like a Chinese character 'ji', and are made of 7075-T6 aluminum alloy materials, and the thickness of the eight corner pieces is 2mm. The turning parts of the corner pieces are transited by circular arcs with the radius of 3 mm.
In order to meet the requirements of the aircraft nose end frame for bird strike resistance performance standard and the requirements of lightweight design, the aircraft nose end frame main beam is fixed on the aircraft nose end frame main beam through the corner pieces, so that interference with an aircraft radar bottom device is avoided. In the invention, a reasonable sandwich structure plays a key role in bird strike resistance of the baffle, if the upper panel and the lower panel are made of the same aluminum alloy material, the baffle can not fully absorb energy or the overall rigidity is too small under the impact of a bird body, as shown in fig. 8, if the lower part of the upper panel and the lower panel are made of 2 series aluminum alloy with smaller rigidity, the baffle deforms greatly to squeeze the end frame panel to damage, and if the upper panel and the lower panel are made of 7 series aluminum alloy with larger rigidity, effective buffering and energy absorption can not be carried out to lead to breakdown of the structure by the bird body, so that the rigidity of the upper panel and the lower panel is required to be reasonably configured to balance the bird strike resistance energy absorption effect and the deformation degree.
The invention improves the bird strike resistance of the aircraft nose, reduces the structural weight and reduces the manufacturing cost. On one hand, the material improvement and the structural optimization are carried out on the upper panel, the lower panel and the sandwich of the bird strike resistant baffle plate in front of the aircraft nose end frame, the overall quality of the bird strike resistant baffle plate is reduced, so that the light weight requirement of the aircraft structural design is better achieved, on the other hand, the connecting structure is improved on the basis of ensuring the original bird strike resistant performance of the aircraft nose, the original C-shaped and I-shaped supporting structure is changed into a 'U' -shaped structure, the bearing capacity of the baffle plate is better, and the structure is not easy to shear damage under impact load.
Under high-speed impact load of birds, the structure can not absorb impact energy and maintain rigidity, and the relation between the structure and the impact energy is difficult to balance in the existing design, so that the weight redundancy of the structural design is caused. The bird body impact energy absorbing structure is characterized in that an upper panel is made of 2024-T3 aluminum alloy with good ductility and is glued with an aluminum foam core material, the upper panel can be greatly deformed and compress a large-area aluminum foam interlayer under impact load bearing to absorb the impact energy as much as possible, a lower panel is made of 7075-T6 aluminum alloy with good thickness and is also connected with the aluminum foam interlayer through gluing, the rigidity of a baffle plate can be maintained as much as possible under the impact load transmitted by an upper layer, the impact load is dispersed to an end frame main beam through a supporting beam and a corner piece, the sandwich layer is made of closed-pore aluminum foam with good energy absorbing effect and the density of about 300kg/m & lt 3 & gt through cutting, and under the impact condition of a bird body of 1.8kg at a speed of 200m/s or lower, the baffle plate effectively utilizes the action of a foam aluminum stress platform section generated by the aluminum foam when the aluminum foam is subjected to the compression load bearing to enable the acting force of bird body tissue to be dispersed, the bird body tissue to be prevented from penetrating through the lower panel, the bird body energy absorbing performance can be maintained as much as possible, the rigidity is possessed at the same time, and the structural weight can be effectively reduced.
Numerical experiments show that the thickness ratio of the upper panel, the lower panel and the core foamed aluminum has great influence on bird strike resistance of the baffle, so that the thickness optimization is carried out through a series of numerical simulations, the thickness of the 2024-T3 aluminum alloy upper panel is finally obtained to be 1.5mm, the thickness of the aluminum foam core material serving as the core layer is 15mm, and when the thickness of the 7075-T6 aluminum alloy lower panel is 1mm, the baffle can bear 1.8kg of high-speed bird body impact under the requirement of navigable standard, the overall structural quality is minimum, and the weight of the structure is reduced by more than 50% relative to that of the original baffle.
The specific optimization process is as follows:
The upper and lower panels and the aluminum foam are subjected to thickness optimization, the thickness of the aluminum foam is sequentially selected to be 20mm, 15mm, 25mm and 10mm, the upper panel and the lower panel with different thicknesses are selected for numerical simulation calculation, and the optimization results are shown in table 1. The optimal result is that the structural weight of the support piece is the lightest when the upper panel, the foamed aluminum sandwich and the lower panel are respectively 1.5mm, 15mm and 1mm, and the bird strike damage of the aircraft nose end frame is effectively prevented, and the structural weight is effectively reduced under the same bird strike resistance performance.
Table 1 summary of thickness optimization
In the prior art, the supporting beam behind the baffle is generally in an I-shaped or C-shaped structure, and under the high-speed impact action of birds, the baffle is easily cut by the I-shaped or C-shaped supporting beam from the edge to generate shearing damage, and the reason is that the edge has larger rigidity mutation. In order to prevent the abrupt change of structural rigidity caused by the action of the panel and the supporting structure under high-speed impact load and further to generate shearing damage, the invention provides a method for replacing an I-shaped or C-shaped supporting beam with a supporting beam and fixing an anti-collision baffle by matching with a corner piece. The support structure in the shape of a Chinese character 'ji' can generate proper collapse deformation when bearing the impact load transmitted by the baffle plate, further absorb impact energy and relieve the abrupt change of structural rigidity, so that the lower panel is not easy to generate shearing damage when colliding with the support structure, thereby improving the bird strike resistance of the whole structure. The bending angles of the shape of a Chinese character 'ji' are transited by circular arcs to relieve stress concentration effect, and the radius of the circular arcs is selected to be 3mm after reasonable optimization. The simulation results for the three support forms are shown in fig. 9. As can be seen from fig. 9, the "table" shaped support can effectively alleviate the rigidity mutation, is not easy to generate shearing damage, and improves the bird strike resistance of the structure.
According to the invention, the baffle is perforated through the lower panel and is connected with the supporting corner pieces in a shape like a Chinese character 'ji', because the impact load of the bird body is transmitted to the supporting corner pieces through the panel and then dispersed on the main beam, the reinforcing gasket and the bolt have a larger influence on the bird strike resistance of the whole structure, if the gasket and the bolt are too large in size, the whole structure is increased more, and the joint is easy to break and fail due to too small size, so that the bird strike resistance of the baffle is weakened, after continuous trial and optimization, the M8 high-strength bolt is selected, and an aluminum alloy gasket with the thickness of 1.5mm and the outer diameter of 16mm is used for connecting the corner pieces and the lower panel.
The corner pieces, the supporting beams and the aircraft end frame panels are riveted on the I-shaped surface of the end frame main beam, and compared with the installation of the original bird strike resistant baffle, no additional working procedure is added, and the operation is simple and convenient.
The invention additionally installs the sandwich anti-bird strike baffle in the aircraft nose and improves the supporting structure, thereby enhancing the anti-bird strike performance of the aircraft nose, fully considering the absorption of impact energy and avoiding the generation of rigidity mutation in the impact process in the structural design. After the baffle is impacted by the bird body, the 2024-T3 aluminum alloy upper panel with better ductility can fully compress the aluminum foam interlayer material to absorb impact kinetic energy, and the 7075-T6 aluminum alloy lower panel with better rigidity can ensure that the rigidity of the baffle meets certain requirements and prevent the baffle from collapsing. The support structure in the shape of a Chinese character 'ji' avoids abrupt change of structural rigidity, can further absorb impact kinetic energy, and avoids shearing damage caused by collision of the sandwich-shaped lower panel and the support structure under impact load. FIG. 7 is a simulated comparison of an equivalent weight of an original baffle and a sandwich baffle and a support structure thereof according to the present invention, and it can be clearly seen that the original structure is broken in a large area and the structure of the present invention can effectively resist bird impact.
Compared with the traditional aluminum honeycomb, the aluminum foam material overcomes the defects of simple structure, anisotropy, higher cost and other functions of the aluminum honeycomb material.
Because the sandwich-shaped bird strike resisting baffle plate is arranged in the radome and is positioned at the position 50mm below the radar, the aerodynamic performance of the machine head and the emission and the receiving of radar signals are not affected, and the manufacturing is simple and the cost is low.
The invention fully considers the defects existing in the existing structure in principle, the baffle cannot effectively absorb and disperse impact energy under the impact load action of the bird body because the weight of the existing reinforced baffle is greatly increased, and the I-shaped supporting beam is easy to cut the anti-collision baffle. Compared with the prior art, the invention has the advantages that:
1. the sandwich baffle plate adopted by the invention can utilize the upper high-ductility aluminum alloy baffle plate to compress the core aluminum foam material to effectively absorb the impact load under the impact load of the bird body, maintain necessary structural rigidity, prevent the bird body from entering the rear part of the end frame, and ensure the safety of the internal structure.
2. The corner piece and the supporting beam provided by the invention can effectively relieve the abrupt change of rigidity, when the baffle is pressed towards the corner piece and the supporting beam by impact load, the right amount of deformation can be generated in the U-shaped structure, the stress concentration phenomenon is avoided through the arc at the turning part of the U-shaped structure, and the defect that the lower panel is easy to shear and damage is avoided.
3. Under the condition of the same bird strike resistance, the quality of the sandwich bird strike resistance baffle and the supporting structure thereof provided by the invention is obviously smaller than that of an aluminum alloy reinforcement scheme in the original structure, and the requirement of light weight of an aircraft structure is better met.
The invention fully considers the parameters such as displacement, plastic strain, energy and the like of the aircraft nose end frame structure during bird strike and the relationship between the bird strike resistance and weight gain of the end frame in the aircraft nose radar cover after the anti-collision baffle is additionally arranged. In both aspects, the applicant has made a great deal of research effort.
At present, a baffle plate with bird strike resistance of a head end frame of a certain commercial aircraft needs to be optimized, and in the technical scheme adopted by the invention, the energy absorption capacity, the rigidity requirement, the supporting structure and the requirement on weight in the aircraft design of a sandwich structure with the bird strike resistance of the head end frame of the aircraft are comprehensively considered, so that the baffle plate has important significance for the bird strike resistance of the head end frame structure of the aircraft, the light weight requirement of the structural design of the aircraft and the improvement of the flight safety of the aircraft. The invention provides a new technical scheme for the future aircraft nose end frame bird strike resistant design.
Drawings
FIG. 1 is a schematic view of the original structure of an aircraft nose end frame bird strike resistant baffle.
Fig. 2 is a schematic structural view of a baffle plate in the present invention.
FIG. 3 is a schematic view of the distribution of support beams and gussets on an end frame panel.
FIG. 4 is a schematic illustration of the connection of the support beams and corner pieces to the end frame main beams.
FIG. 5 is a schematic view of an embodiment of a baffle assembly of the present invention.
Fig. 6 is a composite bird strike resistant barrier for aircraft nose as set forth in CN108099281 a.
Fig. 7 is a simulated comparison of the effects of a bird strike resistant barrier assembly of the prior art and a bird strike resistant barrier assembly of the present invention under an equivalent mass bird strike impact, wherein fig. 7a is prior art and fig. 7b is the present invention.
FIG. 8 is a graph showing a comparison of bird strike resistance under the same mass bird strike impact between an upper panel and a lower panel of the same material and between an upper panel and a lower panel of different materials, wherein the upper panel and the lower panel in FIG. 8a are made of 2024-T3 aluminum alloy, the upper panel and the lower panel in FIG. 8b are made of 7075-T6 alloy, and the upper panel and the lower panel in FIG. 8c are made of different materials.
Fig. 9 is a comparison of impact resistance effects of support structures simulating different cross-sectional shapes, wherein fig. 9a is an i-shaped support impact simulation result, fig. 9b is a C-shaped support impact simulation result, and fig. 9C is a several-shaped support impact simulation result.
In the figure, an aluminum plate, a reinforcing rib, an I-shaped support, an end frame main beam, an upper panel, an aluminum foam core material, a lower panel, a supporting beam, corner pieces, an aircraft end frame panel, a fastening bolt with a gasket, a tooth plate and a composite material plate.
Detailed Description
The embodiment is a baffle assembly capable of improving bird strike resistance of an aircraft nose end frame, and aims to improve the aircraft nose end frame bird strike resistance assembly in the prior art.
The baffle assembly comprises a baffle, five support beams 8 and eight corner pieces 9. The baffle consists of an upper panel 5, a lower panel 7 and an aluminum foam core 6. Five support beams and eight corner pieces in the baffle assembly are riveted on the aircraft end frame panel, and each rivet is fixed on the end frame main beam respectively. Specifically, five support beams are distributed along the width direction of the end frame main beam, and are parallel to the length direction of the end frame main beam, and the distance between the central lines of the adjacent support beams in the width direction is 170mm.
The aluminum foam core material is adhered between the upper panel and the lower panel to form a sandwich structure.
The lengths and widths of the upper panel 5, the lower panel 7 and the aluminum foam core material 6 are determined according to the size of the aircraft nose end frame inner cavity and are slightly smaller than the aircraft nose end frame inner cavity. The radar mounting port is formed by a groove on one long side of the upper panel and is used as a reserved radar mounting port, and the position and the size of the radar mounting port are determined according to the actual radar type. The upper panel is made of 2024-T3 aluminum alloy and has a thickness of 1.5mm. The lower panel is made of 7075-T6 aluminum alloy and has a thickness of 1mm. The aluminum foam has an aluminum density of 300kg/m 3 and a thickness of 15mm.
The cross sections of the five supporting beams 8 are all in a shape like a Chinese character 'ji', and are made of 7075-T6 aluminum alloy materials, and the thickness is 2mm. The turning parts of the supporting beams are transited by circular arcs with the radius of 3mm. The five support beams 8 are distributed in a direction perpendicular to the end frame main beams 4, and the distance between the width direction center lines of the adjacent support beams is 170mm. The length and width of the five support beams 8 are matched with the size of the baffle.
The cross sections of the eight corner pieces 9 are all in a shape like a Chinese character 'ji', and are made of 7075-T6 aluminum alloy materials, and the thickness is 2mm. The turning parts of the corner pieces are transited by circular arcs with the radius of 3 mm. The eight corner pieces are divided into three groups by numbers of 3, 2 and 3, the three groups of corner pieces are positioned on the surface of the aircraft end frame panel 10, two groups of 3 corner pieces are respectively positioned at two ends of the aircraft end frame panel, and one group of 2 corner pieces is positioned in the middle of the aircraft end frame panel. The distance between the central lines of the adjacent two groups of corner pieces in the width direction is 340mm, and the geometric center distance between the adjacent two corner pieces in each group of corner pieces is 340mm
The support beams and corner pieces of the baffle assembly are riveted to the aircraft end frame panel 10 and the rivets are secured to the end frame main beams 4. The rivet is a CPH rivet with the diameter of 3.2 mm.
The baffle is placed on the upper surface of the support beam 8 and is in a natural contact state therebetween.
The rivet adopts a high-strength rivet with the diameter of 3.2mm, and the supporting beam 8 is fixed with the lower panel 7 through a fastening bolt 11 with a gasket.
In this embodiment, the end frame main beam 4 is made of 7075-T6 aluminum alloy with a thickness of 6mm, the aircraft end frame panel is made of 2024-T3 aluminum alloy with a thickness of 1mm, and the baffle needs to bypass the installation position of the airborne radar, so that the baffle can be cut according to the actual structural requirement.
When the aircraft end frame main beam 4 is assembled, firstly, the lower panel 7 is connected with the corner pieces 9 by using the fastening bolts 11 with gaskets, then the upper panel 5, the aluminum foam 6 and the lower panel 7 are respectively glued, the supporting beam 8, the aircraft end frame panel 10 and the end frame main beam 4 are riveted by using CPH rivets, and finally, the high-strength rivet corner pieces 9 are riveted to the end frame main beam 4.
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|---|---|---|---|---|
| CN102490912A (en) * | 2011-11-08 | 2012-06-13 | 西安交通大学 | Space debris prevention structure of spacecraft |
| CN103373463A (en) * | 2012-04-19 | 2013-10-30 | 尤洛考普特公司 | Aircraft airfoil, and an aircraft provided with such an airfoil |
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| US7866605B2 (en) * | 2007-04-24 | 2011-01-11 | The Boeing Company | Energy absorbing impact band and method |
| EP2865516B1 (en) * | 2013-10-28 | 2016-03-09 | AIRBUS HELICOPTERS DEUTSCHLAND GmbH | Skin-stiffened composite panel and method of its manufacture |
| FR3013676B1 (en) * | 2013-11-27 | 2017-05-05 | Eurocopter France | AIRCRAFT PROVIDED WITH A SHOCK TREATMENT SYSTEM IN HOUSING CLOSED BY A RADOME FOLLOWING AN IMPACT WITH AN EXTERNAL OBJECT |
| CN106393915A (en) * | 2016-08-31 | 2017-02-15 | 西安立远新材料科技开发有限公司 | Anti-collision board and manufacturing method thereof |
| CN109455290A (en) * | 2018-10-25 | 2019-03-12 | 中国民航大学 | A kind of cargo deck lower part endergonic structure unit for fitting pendant property for improving aircraft |
| DE102018130857A1 (en) * | 2018-12-04 | 2020-06-04 | Airbus Defence and Space GmbH | Impact protection plate for vehicles, in particular aircraft |
| CN112298523A (en) * | 2020-11-06 | 2021-02-02 | 一飞智控(天津)科技有限公司 | An electric heavy-duty multi-rotor unmanned aerial vehicle fuselage |
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| CN102490912A (en) * | 2011-11-08 | 2012-06-13 | 西安交通大学 | Space debris prevention structure of spacecraft |
| CN103373463A (en) * | 2012-04-19 | 2013-10-30 | 尤洛考普特公司 | Aircraft airfoil, and an aircraft provided with such an airfoil |
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