A baffle assembly capable of improving the bird strike resistance of an aircraft nose end frame

Abstract

A baffle assembly capable of improving the bird strike resistance of an aircraft nose end frame, wherein the five support beams with a "J"-shaped cross section and the eight corner pieces with a "J"-shaped cross section in the baffle assembly are riveted to the aircraft end frame panel, and each rivet is fixed to the end frame main beam. The baffle, which is 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 placed on the upper surface of the support beam. In the present invention, a reasonable sandwich structure plays a key role in the bird strike resistance of the baffle, improves the bird strike resistance of the aircraft nose, reduces the structural weight and reduces the manufacturing cost. Test specimens have shown that when a 1.8 kg bird body hits at a speed of less than 200 m / s, the baffle effectively utilizes the energy absorption effect of the foam aluminum stress platform section generated by the aluminum foam when it is subjected to a compressive load, so that the force acting on the bird body tissue is dispersed, preventing it from penetrating the lower panel, and effectively reduces the structural weight while maintaining the bird strike resistance and having sufficient rigidity.

Description

Technical Field

[0001] The invention relates to the field of aircraft structure design, in particular to a baffle and a supporting member thereof which can improve the bird strike resistance performance of an aircraft nose end frame and reduce the weight. Background Art

[0002] A bird strike occurs when an aircraft or other aircraft collides with a flying bird. With the rapid development of the civil aviation industry, bird strikes have become one of the most serious safety threats to civil aviation. According to a United Airlines report, between 1990 and 2008, US civil aviation reported 89,727 animal-aircraft collisions, 97.4% of which were caused by birds. Data shows that the windward side of an aircraft, including the windshield, radome, engine, wing leading edge, and tail leading edge, is most vulnerable to bird strikes. Behind the inner end frame of the aircraft's nose radome are various electronic equipment and control circuits. Damage to these internal components by a bird strike can be catastrophic. Therefore, addressing the bird strike resistance of the aircraft's nose end frame is of paramount importance. The first clause of Article 25.571(e) of the Airworthiness Standards for Transport Category Airplanes formulated by the Civil Aviation Administration of China clearly stipulates that for each structural part that may cause catastrophic damage, the aircraft must be able to successfully complete the flight when hit by a 1.8kg bird at various altitudes from sea level to 2450m and at a speed of Vc. Studies have shown that under high-speed impacts, birds exhibit obvious fluid dynamics behavior. Since the nose radome currently uses a thin layer of glass fiber paper honeycomb sandwich structure, high-speed birds can easily penetrate the radome and only lose about 5% of kinetic energy. Therefore, when designing the structure of the aircraft nose area, in order to meet the anti-bird strike requirements, an anti-bird strike baffle assembly is added to the end frame structure of the nose radar compartment. This baffle ( Figure 1 ) is composed of an aluminum plate 1 and a reinforcement rib 2 made by milling 7075-T6 aluminum alloy. The baffle is connected to the I-shaped support 3 and riveted to the nose end frame main beam 4. However, the excessive weight increase of the baffle assembly is not conducive to improving the economy of the aircraft.

[0003] Compared with traditional honeycomb aluminum, foam aluminum overcomes the drawbacks of aluminum honeycomb, such as simple structure, anisotropy, and high cost. In addition, aluminum honeycomb has poor plasticity, and many plate shapes cannot be processed using aluminum honeycomb. Foam aluminum is one of the most ideal materials for energy absorption and collision prevention in current industrial materials, with an energy absorption density of 4 to 20 J / cm 3, and has a wide and flat stress platform, which can continuously absorb energy throughout the compression process. In the field of high-strength anti-collision cushioning, it has irreplaceable superior performance. Foam aluminum materials have been used in landing cushioning of the return capsule of the Shenzhou spacecraft series and landing cushioning of the Chang'e lunar rover. Studies have shown that foam aluminum and high-strength materials such as high-strength steel, special ceramics, and aramid fiberboard form a new type of composite armor. The energy absorption effect of foam aluminum is used to disperse the force of armor-piercing and armor-piercing projectiles, preventing them from entering the interior. While maintaining high protection performance, it can effectively reduce the weight of the structure. Therefore, foam aluminum material also has great application potential in the design of bird-strike resistant structures, and can further optimize and reduce the weight of the structure under the same bird-strike resistant performance. However, there are still some key issues that have not been resolved when applying aluminum foam materials to the anti-bird strike structure of the nose end frame. For example, the anti-bird strike performance of the sandwich structure under the high-speed impact of the bird is closely related to the thickness ratio of its layers and the aluminum alloy material grade of the upper and lower panels. An inappropriate baffle may cause the aluminum panel to tear rapidly or collapse due to insufficient rigidity under the action of high-speed impact loads, thereby significantly affecting its impact resistance and energy absorption effect. In addition, the support between the anti-collision baffle and the end frame main beam also significantly affects the anti-bird strike effect of the baffle. Currently, C-shaped or I-shaped supports are often used. Under the action of high-speed impact loads, the lower panel is very likely to suffer shear failure at the C-shaped and I-shaped supports, resulting in failure of the anti-collision structure. In summary, there is still a lot of room for optimization in the application of aluminum foam sandwich structures to the anti-bird strike of the nose end frame. It is necessary to improve the design of the baffle assembly and the support structure to improve the anti-bird strike performance of the baffle assembly and reduce the weight of the aircraft structure.

[0004] Professor Li Yulong of Northwestern Polytechnical University and his team have long been engaged in research on aircraft bird strike resistance and have achieved relevant results. These research efforts focus on improving the bird strike resistance of aircraft horizontal tail leading edges and aircraft tail fins. For example, the invention with publication number CN102030102A discloses a bird strike-resistant aircraft horizontal tail leading edge, and the invention with publication number CN102390520A discloses a tail fin that can improve aircraft bird strike resistance. The bird strike resistance design of this tail fin structure adopts the design concept of bird energy diversion. By setting up double inclined plates at appropriate angles, when the tail fin is impacted by a high-speed bird, the skin can deform appropriately and adhere to the double inclined plates. The bird can slide along the outer side of the double inclined plates, diverting most of the impact energy. As a result, the above inventions improve the structure's bird strike resistance.

[0005] As for the nose structure, the presence of the radar precludes the installation of similar energy-conducting structures within the radome. Currently, 7075 reinforced baffles are typically used to directly resist bird strikes, resulting in significant weight gain. Therefore, this paper proposes a novel bird-strike-resistant baffle and assembly based on the concept of using metal foam to buffer bird impact energy.

[0006] The invention of CN108099281A discloses a composite anti-bird impact baffle for aircraft nose. The baffle is composed of a tooth plate 12 and a composite material plate 13, and the tooth plate 12 is located on the outside of the composite material plate 13. There are protrusions distributed on the surface of the tooth plate 12, which will play a role in breaking the bird bones and dispersing the impact force when a bird hits it, reducing the volume and improving the maintainability of the radar cover. The composite material plate 13 in the baffle adopts an aluminum honeycomb sandwich structure. However, the plasticity of aluminum honeycomb is poor, and there are many plate types that cannot be processed using aluminum honeycomb. At the same time, the invention does not consider the support connection problem between the baffle and the nose end frame. Currently, C-shaped or I-shaped supports are often used. Under the action of high-speed impact loads, the lower panel is very likely to undergo shear damage at the C-shaped and I-shaped supports, resulting in failure of the anti-collision structure.

[0007] In the paper "Anumerical model for bird strikes of aluminum foam-based sandwich panels" (International Journal of Impact Engineering, 2006), AGHanssen proposed a sandwich panel. The upper and lower panels of this sandwich panel are both made of AA2024T3 aluminum alloy, and the core is an aluminum foam structure. Simulations have shown that this structure has good bird strike resistance. However, the upper and lower panels are made of the same 1.66mm thick aluminum alloy sheet, bonded to both sides of the core. This results in insufficient stiffness for the lower panel under bird impact loads, posing a risk of tearing. Furthermore, the thickness of the upper and lower panels and the core were not optimized, and the supporting structure was not improved. In "Numerical Analysis of Bird Strike on Honeycomb Sandwich Radome Structure" (Explosion and Shockwave, 2009), Li Yulong et al. used the nonlinear dynamics finite element software PAM-CRASH to numerically analyze the process of bird strikes on honeycomb sandwich radomes. The results showed that honeycomb sandwich radomes cannot withstand high-speed bird impacts, necessitating the installation of bird-strike shields within the radome to meet aircraft airworthiness certification requirements. In "Analysis and Design of Bird Strike Resistance for a Sandwich Structure" (Acta Aeronautica et al., 2012), Li Yulong et al. optimized the design of a shield in an aircraft using a multilayer honeycomb sandwich structure and filling the shield with a rigid foam material. However, the shield support structure was not modified, resulting in a significant increase in structural weight. Summary of the Invention

[0008] In order to overcome the shortcomings of the existing technology of excessive weight of anti-bird strike structures and unreasonable baffle support design, the present invention proposes a baffle assembly that can improve the anti-bird strike performance of the aircraft nose end frame.

[0009] The present invention includes a baffle plate, five support beams, and eight corner pieces. The five support beams and the eight corner pieces in the baffle plate assembly are all riveted to the aircraft end frame panel, and each rivet is fixed to the main beam of the end frame respectively. Specifically, the five support beams are distributed along the width direction of the main beam of the end frame, and the five support beams are all parallel to the length direction of the main beam of the end frame; the distance between the center lines in the width direction of adjacent support beams is 170 mm. The eight corner pieces are divided into three groups with the numbers 3, 2, and 3; the three groups of corner pieces are located on the surface of the aircraft end frame panel, and the two groups with 3 corner pieces are respectively located at both ends of the aircraft end frame panel, and the group with 2 corner pieces is located in the middle of the aircraft end frame panel. There are two support beams between each group of corner pieces; the distance between the center lines in the width direction of adjacent two groups of corner pieces is 340 mm, and in each group of corner pieces, the distance between the geometric centers of adjacent two corner pieces is also 340 mm

[0010] The baffle plate is placed on the upper surface of the support beam, and the two are in a natural contact state

[0011] The baffle plate is composed of an upper panel, a lower panel, and an aluminum foam core. Among them, the aluminum foam core is bonded between the upper panel and the lower panel to form a sandwich structure

[0012] The length and width of the baffle plate assembly are both 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. There is a reserved radar installation port on one long side of the upper panel

[0013] The upper panel is made of 2024-T3 aluminum alloy with a thickness of 1.5 mm. The lower panel is made of 7075-T6 aluminum alloy with a thickness of 1 mm. The aluminum density of the aluminum foam is 300 kg / m 3 and the thickness is 15 mm

[0014] The cross sections of the five support beams are all "U" shaped, made of 7075-T6 aluminum alloy material with a thickness of 2 mm. The turning points of each support beam are all transitioned with an arc with a radius of 3 mm. The length and width of the five support beams are both matched with the size of the baffle plate

[0015] The cross sections of the eight corner pieces are all "U" shaped, made of 7075-T6 aluminum alloy material with a thickness of 2 mm. The turning points of each corner piece are all transitioned with an arc with a radius of 3 mm

[0016] To simultaneously meet the requirements of the anti-bird-strike performance standard of the aircraft nose end frame and the requirements of lightweight design, the present invention is fixed to the main beam of the nose end frame through corner pieces, thus avoiding interference with the bottom devices of the aircraft radar. In the present invention, a reasonable sandwich structure plays a key role in the anti-bird-strike performance of the baffle plate. If the same aluminum alloy material is selected for the upper and lower panels, it will cause the baffle plate to not fully absorb energy or the overall stiffness to be too small under the impact of a bird body, such as Figure 8 As shown, if the upper panel and the lower panel are both made of 2 series aluminum alloy with lower rigidity, the baffle will deform greatly and squeeze the end frame panel to cause damage. If both the upper panel and the lower panel are made of 7 series aluminum alloy with higher rigidity, they will not be able to effectively buffer and absorb energy, resulting in the structure being penetrated by the bird. Therefore, it is necessary to reasonably configure the rigidity of the upper and lower panels to balance the anti-bird impact energy absorption effect and the degree of deformation. The sandwich structure proposed in the present invention uses 2024-T3 aluminum alloy for the upper panel and 7075-T6 aluminum alloy for the lower panel, which can effectively balance the two factors and achieve better anti-bird impact effect.

[0017] This invention improves the bird-strike resistance of an aircraft nose while reducing structural weight and manufacturing costs. Firstly, by improving the materials and optimizing the structure of the upper and lower panels and core of the anti-bird-strike baffle in front of the aircraft nose end frame, the overall mass of the baffle is reduced, thereby better meeting the lightweight requirements of aircraft structural design. Secondly, while maintaining the original bird-strike resistance of the aircraft nose, the connection structure is improved, replacing the original C-shaped and I-shaped support structures with a "J"-shaped structure. This improves the baffle's load-bearing capacity and makes the structure less susceptible to shear failure under impact loads.

[0018] Under the high-speed impact load of a bird's body, it is often difficult for the structure to absorb and buffer the impact energy and maintain stiffness at the same time. It is difficult to balance the relationship between the two in existing designs, resulting in weight redundancy in the structural design. In order to disperse and absorb the impact energy of the bird while maintaining structural rigidity, the present invention has an upper panel made of 2024-T3 aluminum alloy with good ductility and bonded with an aluminum foam core material. When subjected to an impact load, the upper panel can undergo a large deformation and compress a large area of the aluminum foam interlayer to absorb as much impact energy as possible; the lower panel is made of 7075-T6 aluminum alloy with a thickness of 1.5mm and good rigidity, and is also connected to the aluminum foam interlayer by bonding. Under the impact load transmitted from the upper layer, the baffle can maintain the rigidity of the baffle as much as possible and disperse the impact load to the end frame main beam through the support beam and the corner piece; the sandwich layer is cut from closed-cell aluminum foam with a density of about 300kg / m3 with good energy absorption effect. When a 1.8kg bird hits at a speed of less than 200m / s, the baffle effectively utilizes the energy absorption effect of the foam aluminum stress platform section generated by the aluminum foam when it is subjected to a compression load, so that the force of the bird tissue is dispersed and prevented from penetrating the lower panel. It also has sufficient rigidity while maintaining anti-bird impact performance, which can effectively reduce the weight of the structure.

[0019] Numerical experiments show that the thickness ratio of the upper and lower panels, as well as the core aluminum foam, significantly influences the baffle's bird strike resistance. Therefore, a series of numerical simulations were conducted to optimize the thickness. The result was a 1.5mm thickness for the 2024-T3 aluminum alloy upper panel, a 15mm thickness for the aluminum foam core layer, and a 1mm thickness for the 7075-T6 aluminum alloy lower panel. This resulted in the baffle being able to withstand the 1.8kg high-speed bird impact required by airworthiness standards while minimizing overall structural mass. This structure achieved a weight reduction of over 50% compared to the original baffle.

[0020] The specific optimization process is as follows:

[0021] The thicknesses of the upper and lower panels and aluminum foam were optimized, with aluminum foam thicknesses selected as 20 mm, 15 mm, 25 mm, and 10 mm, respectively. Numerical simulations were performed on upper and lower panels of varying thickness, with the optimization results shown in Table 1. The optimal result was achieved when the upper panel, aluminum foam core, and lower panel thicknesses were 1.5 mm, 15 mm, and 1 mm, respectively. This achieved the lightest structural weight for the support component and effectively prevented bird strike damage to the aircraft's nose end frame, effectively reducing structural weight while maintaining the same bird strike resistance.

[0022] Table 1 Thickness optimization summary

[0023]

[0024]

[0025] In the prior art, the support beam behind the baffle generally adopts an I-shaped or C-shaped structure. Under the high-speed impact of the bird, the baffle is easily cut from the edge by the I-shaped or C-shaped support beam to cause shear damage. The reason is that there is a large stiffness mutation at the edge. In order to prevent the panel and the support structure from forming a sudden change in structural stiffness under high-speed impact loads and then causing shear damage, the present invention proposes to replace the I-shaped or C-shaped support beam with a support beam, and use corner pieces to fix the anti-collision baffle. The "J"-shaped support structure can undergo appropriate collapse and deformation when it is subjected to the impact load transmitted by the baffle, further absorb the impact energy and alleviate the sudden change in structural stiffness, so that shear damage is not easy to occur when the lower panel collides with the support structure, thereby improving the overall structure's anti-bird impact performance. The "J"-shaped bending corners are all transitioned with arcs to reduce the stress concentration effect. After reasonable optimization, the radius of the arc is selected to be 3mm. The simulation results of the three support forms are as follows. Figure 9 As shown. Figure 9 It can be seen that the "J"-shaped support can effectively alleviate the sudden change in stiffness, making shear failure less likely to occur, and improving the structure's anti-bird strike performance.

[0026] The baffle described in the present invention is connected to the "J"-shaped supporting angle piece through the opening in the lower panel using reinforcing gaskets and bolts. Since the impact load of the bird body is transmitted to the supporting angle piece through the panel and then dispersed to the main beam, the reinforcing gaskets and bolts have a great influence on the bird-strike resistance of the overall structure. If the gaskets and bolts are selected to be too large, the overall structure will increase in weight, while if the size is too small, the connection will easily break and fail, weakening the bird-strike resistance of the baffle. After continuous attempts and optimization, the present invention selects M8 high-strength bolts and uses aluminum alloy gaskets with a thickness of 1.5mm and an outer diameter of 16mm to connect the angle piece and the lower panel.

[0027] The corner pieces and support beams are riveted together with the aircraft end frame panels on the I-shaped surface of the end frame main beam. Compared with the original anti-bird strike baffle installation, no additional steps are added and the operation is simple and convenient.

[0028] The present invention adds a sandwich-shaped anti-bird strike baffle to the nose of the aircraft and improves the supporting structure, thereby enhancing the anti-bird strike performance of the aircraft nose. The structural design fully considers the absorption of impact energy and the avoidance of sudden changes in stiffness during the impact. After the baffle is subjected to the impact load of the bird body, the 2024-T3 aluminum alloy upper panel with better ductility can fully compress the aluminum foam sandwich material to absorb the impact kinetic energy, and the 7075-T6 aluminum alloy lower panel with better rigidity can ensure that the baffle stiffness meets certain requirements and prevent the baffle from collapsing. The "J"-shaped support structure avoids sudden changes in structural stiffness and can further absorb impact kinetic energy, preventing the sandwich-shaped lower panel from colliding with the support structure under the impact load and causing shear damage. Figure 7 This is a simulation comparison diagram of the bird strike resistance of the original baffle of equal weight and the sandwich baffle and its supporting structure proposed by the present invention. It can be clearly seen that the original structure has large-scale damage, while the structure of the present invention can effectively resist the impact of the bird.

[0029] Compared with traditional honeycomb aluminum, the present invention uses foam aluminum material to overcome the shortcomings of aluminum honeycomb materials such as simple structure, anisotropy, high cost and other functional deficiencies.

[0030] Since the present invention installs a sandwich-shaped anti-bird impact baffle inside the radar cover and the anti-bird impact baffle is located 50 mm below the radar, it will not cause any impact on the aerodynamic performance of the nose and the transmission and reception of radar signals, and is simple to manufacture and low in cost.

[0031] The present invention addresses the shortcomings of existing structures. Existing reinforced baffles significantly increase weight, making them ineffective at absorbing and dissipating impact energy from bird strikes. Furthermore, the I-shaped support beams are prone to cutting through the baffles. Compared to existing technologies, the present invention offers the following advantages:

[0032] 1. The sandwich baffle used in the present invention can utilize the upper high-ductility aluminum alloy baffle to compress the core aluminum foam material to effectively absorb the impact load under the impact load of the bird body, maintain the necessary structural rigidity, prevent the bird body from entering the rear of the end frame, and ensure the safety of the internal structure.

[0033] 2. The corner pieces and support beams proposed in the present invention can effectively alleviate sudden changes in stiffness. When the baffle is pressed toward the corner pieces and support beams by an impact load, the "J"-shaped structure will deform appropriately, and the arc at the turning point of the "J"-shaped structure will avoid stress concentration, thereby avoiding the weakness of the lower panel that is prone to shear damage.

[0034] 3. Under the condition of the same bird strike resistance performance, the sandwich-shaped bird strike resistance baffle and its supporting structure proposed by the present invention are significantly lighter than the aluminum alloy reinforcement scheme in the original structure, which better meets the requirements of lightweight aircraft structure.

[0035] This invention fully considers parameters such as displacement, plastic strain, and energy of the nose end frame structure during a bird strike, as well as the relationship between the bird strike resistance and weight gain of the aircraft nose radome inner end frame after the addition of a crash barrier. The applicant has conducted extensive research on these two aspects.

[0036] Currently, the bird strike protection baffles for the nose end frame of certain commercial aircraft require optimization. The technical solution adopted by this invention comprehensively considers the energy absorption capacity, stiffness requirements, support structure, and weight requirements of the sandwich structure for bird strike protection. This is of great significance for improving the bird strike protection performance of the nose end frame structure, meeting the lightweight requirements of aircraft structural design, and improving aircraft flight safety. This invention provides a new technical solution for future aircraft nose end frame bird strike protection designs. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 This is a schematic diagram of the original structure of the aircraft nose end frame anti-bird strike baffle.

[0038] Figure 2 Schematic diagram of the structure of the baffle in the present invention.

[0039] Figure 3 Schematic diagram of the distribution of support beams and angle pieces on the end frame panel.

[0040] Figure 4 Schematic diagram of the connection between the support beam and angle piece and the end frame main beam.

[0041] Figure 5 This is a schematic diagram of an implementation case of the baffle assembly of the present invention.

[0042] Figure 6 The invention relates to a composite material anti-bird strike baffle for an aircraft nose proposed in CN108099281A.

[0043] Figure 7 This is a simulated comparison diagram of the effects of the anti-bird impact baffle assembly in the prior art and the anti-bird impact baffle assembly proposed in the present invention under the impact of a bird with the same mass; wherein, Figure 7 a is prior art, Figure 7 b is the present invention.

[0044] Figure 8 This is a comparison chart of the bird strike resistance of the upper and lower panels with the same material and the upper and lower panels with different materials under the impact of the same mass bird strike; Figure 8 a. The upper and lower panels are made of 2024-T3 aluminum alloy. Figure 8 b. The upper and lower panels are made of 7075-T6 alloy. Figure 8 c. The upper panel and the lower panel in the present invention are made of different materials.

[0045] Figure 9 To simulate the impact resistance of support structures with different cross-sectional shapes; Figure 9 a is the impact simulation result of the I-shaped support, Figure 9 b is the C-shaped support impact simulation result, Figure 9 c is the impact simulation result of the X-shaped support.

[0046] In the figure: 1. Aluminum plate; 2. Reinforcement ribs; 3. I-shaped support; 4. End frame main beam; 5. Upper panel; 6. Aluminum foam core; 7. Lower panel; 8. Support beam; 9. Angle piece; 10. Aircraft end frame panel; 11. Fastening bolts with washers; 12. Threaded plate; 13. Composite material plate. DETAILED DESCRIPTION

[0047] This embodiment is a baffle assembly capable of improving the bird strike resistance performance of an aircraft nose end frame. It is an improvement on the aircraft nose end frame bird strike resistance assembly in the prior art to achieve the purpose of the present invention.

[0048] The baffle assembly comprises a baffle, five support beams 8, and eight corner pieces 9. The baffle is composed of an upper panel 5, a lower panel 7, and an aluminum foam core 6. The five support beams and eight corner pieces in the baffle assembly are riveted to the aircraft end frame panel, with each rivet secured to the end frame main beam. Specifically, the five support beams are distributed along the width of the end frame main beam and parallel to the length of the end frame main beam. The distance between the width centerlines of adjacent support beams is 170 mm.

[0049] The aluminum foam core material is bonded between the upper panel and the lower panel to form a sandwich structure.

[0050] The lengths and widths of the upper panel 5, the lower panel 7, and the aluminum foam core 6 are determined according to the dimensions of the inner cavity of the aircraft nose end frame and are slightly smaller than the inner cavity of the aircraft nose end frame. There is a groove on one long side of the upper panel as a reserved radar installation port; the position and size of the radar installation port are determined according to the actual radar model. The upper panel is made of 2024-T3 aluminum alloy with a thickness of 1.5 mm. The lower panel is made of 7075-T6 aluminum alloy with a thickness of 1 mm. The aluminum density of the aluminum foam is 300 kg / m 3 , and the thickness is 15 mm.

[0051] The cross-sections of the five support beams 8 are all "U" shapes, made of 7075-T6 aluminum alloy material with a thickness of 2 mm. The transitions at the turns of each support beam are all rounded with a radius of 3 mm. The five support beams 8 are distributed perpendicular to the end frame main beam 4, and the distance between the center lines in the width direction of adjacent support beams is 170 mm. The lengths and widths of the five support beams 8 are both matched with the baffle size.

[0052] The cross-sections of the eight gussets 9 are all "U" shapes, made of 7075-T6 aluminum alloy material with a thickness of 2 mm. The transitions at the turns of each gusset are all rounded with a radius of 3 mm. The eight gussets are divided into three groups according to the numbers 3, 2, and 3; the three groups of gussets are located on the surface of the aircraft end frame panel 10, and the two groups with 3 gussets are respectively located at both ends of the aircraft end frame panel, and the group with 2 gussets is located in the middle of the aircraft end frame panel. There are two support beams between each group of gussets; the distance between the center lines in the width direction of adjacent two groups of gussets is 340 mm, and in each group of gussets, the geometric center distance between adjacent two gussets is also 340 mm

[0053] The multiple support beams and multiple gussets in the baffle assembly are all riveted to the aircraft end frame panel 10, and each rivet is respectively fixed on the end frame main beam 4. The rivets are Φ3.2 mm CPH rivets.

[0054] The baffle is placed on the upper surface of the support beam 8, and they are in a natural contact state.

[0055] The rivets are high-strength rivets with a diameter of 3.2 mm, and the support beam 8 is fixed to the lower panel 7 through a fastening bolt 11 with a gasket.

[0056] In this embodiment, the end frame main beam 4 is made of 7075-T6 aluminum alloy with a thickness of 6 mm; the aircraft end frame panel is made of 2024-T3 aluminum alloy with a thickness of 1 mm; the baffle needs to avoid the on-board radar installation position, so the baffle can be cut according to the actual structural requirements.

[0057] During assembly, first, use the fastening bolts 11 with gaskets to connect the lower panel 7 and the corner piece 9, then glue the upper panel 5, aluminum foam 6, and lower panel 7 separately, use CPH rivets to rivet the support beam 8, aircraft end frame panel 10 and end frame main beam 4, and finally use high-strength rivets to rivet the corner piece 9 to the end frame main beam 4.

Claims

1. A baffle assembly capable of improving the bird strike resistance of an aircraft nose end frame, characterized in that: It includes a baffle plate, five support beams and eight corner pieces; the five support beams and eight corner pieces in the baffle plate assembly are riveted to the aircraft end frame panel, and each rivet is fixed to the main end frame beam respectively; specifically, the five support beams are distributed along the width direction of the main end frame beam, and the five support beams are all parallel to the length direction of the main end frame beam; the distance between the center lines in the width direction of adjacent support beams is 170 mm; the eight corner pieces are divided into three groups with the numbers 3, 2, 3; the three groups of corner pieces are located on the surface of the aircraft end frame panel, and the two groups with 3 corner pieces are respectively located at both ends of the aircraft end frame panel, and the group with 2 corner pieces is located in the middle of the aircraft end frame panel; there are two support beams between each group of corner pieces; the distance between the center lines in the width direction of adjacent two groups of corner pieces is 340 mm, and in each group of corner pieces, the distance between the geometric centers of adjacent two corner pieces is 340 mm; The baffle plate is placed on the upper surface of the support beam, and the two are in a natural contact state; The baffle plate is composed of an upper panel, a lower panel and an aluminum foam core material. Among them, the aluminum foam core material is bonded between the upper panel and the lower panel to form a sandwich structure; The cross sections of the five support beams are all "U" shaped, made of 7075-T6 aluminum alloy material, with a thickness of 2 mm; the transitions at the turning points of each support beam are all rounded with a radius of 3 mm; the lengths and widths of the five support beams match the dimensions of the baffle plate; The cross sections of the eight corner pieces are all "U" shaped, made of 7075-T6 aluminum alloy material, with a thickness of 2 mm; the transitions at the turning points of each corner piece are all rounded with a radius of 3 mm; The upper panel is made of 2024-T3 aluminum alloy with a thickness of 1.5mm; the lower panel is made of 7075-T6 aluminum alloy with a thickness of 1mm; the aluminum density of the aluminum foam is 300kg / m 3 , thickness is 15mm.

2. The baffle assembly capable of improving the bird strike resistance of an aircraft nose end frame according to claim 1, characterized in that: The length and width of the baffle plate assembly are determined according to the dimensions of the inner cavity of the aircraft nose end frame, and are slightly smaller than the inner cavity of the aircraft nose end frame; there is a reserved radar installation port on one long side of the upper panel.

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