Concentrated impact load protection reinforcing structure of aircraft skin thin-wall structure

Abstract

The invention belongs to the technical field of aviation, and relates to a concentrated impact load protection reinforcing structure of an aircraft skin thin-wall structure. Comprising an aircraft left side skin opening (2), an aircraft inner side reinforcing base plate (3), a multi-layer composite laminated board (4), an aviation foam interlayer (5) and a connecting adhesive film (6), an annular groove is formed in the surface of the multi-layer composite laminated board (4), and the aviation foam interlayer (5) is arranged in the annular groove; the airplane inner side reinforcing base plate (3) is positioned on the inner side of the skin by taking the left side skin opening (2) as the center and is connected with the airplane skin through rivets; the multi-layer composite laminated board (4) is positioned on the outer side of the skin with the left skin opening (2) as the center and connected with the aircraft skin through rivets after being bonded to the outer surface of the aircraft skin through the connecting adhesive film (6), the connecting adhesive film (6) is an SY-24C-300 adhesive film, and the launching device (1) extends out of an aircraft cabin through the aircraft left skin opening (2) after being installed and fixed in the aircraft cabin.

Description

Technical Field

[0001] The invention belongs to the field of aviation technology and relates to a concentrated impact load protection and reinforcement structure for an aircraft skin thin-wall structure. Background Art

[0002] When the launcher is working, it generates a large concentrated impact recoil and vibration load, and at the same time, it generates a large shock wave. The impact load will cause periodic fatigue damage to the aircraft thin-walled skin opening stress concentration area structure (such as skin cracks and diffusion). The shock wave peak causes a jump-like change in the pressure, temperature, density and other physical properties of the medium, which will cause strong destructive effects and endanger the aircraft structure safety, flight safety and other aspects. Therefore, it is necessary to adopt a concentrated impact load protection and strengthening structure for the aircraft skin thin-walled structure to solve such problems. Summary of the invention

[0003] Purpose of the invention: To provide a concentrated impact load protection and reinforcement structure for a thin-walled aircraft skin structure, which can meet both the requirements of use and the requirements of aircraft structure and flight safety.

[0004] Technical solution:

[0005] A concentrated impact load protection reinforcement structure for a thin-walled aircraft skin structure comprises: an aircraft left side skin opening 2, an aircraft inner side reinforcement pad 3, a multi-layer composite laminate 4, an aviation foam interlayer 5, and a connecting adhesive film 6, wherein an annular groove is provided on the surface of the multi-layer composite laminate 4, and an aviation foam interlayer 5 is provided in the annular groove; the aircraft inner side reinforcement pad 3 is positioned on the inner side of the skin with the left side skin opening 2 as the center and connected to the aircraft skin through rivets; the multi-layer composite laminate 4 is positioned on the outer side of the skin with the left side skin opening 2 as the center, and is bonded to the outer surface of the aircraft skin with a connecting adhesive film 6 and then connected to the aircraft skin through rivets, and the connecting adhesive film 6 is a SY-24C-300 adhesive film, and a launch device 1 is installed and fixed in the cabin and then extends out of the cabin through the aircraft left side skin opening 2.

[0006] Furthermore, there are two annular grooves and both are filled with aviation foam interlayers 5 .

[0007] Furthermore, the surface layers of the multi-layer composite laminate 4 are upper and lower outer layers, each with 2 layers, and the material is 3218Z / SW110A δ0.11.

[0008] Furthermore, the inner layer of the multi-layer composite laminate 4 is [0 / 45 / 90 / -45 / -90 / 0]6s, and the material is 3218Z / EW220δ0.22.

[0009] Furthermore, the outer shape of the multi-layer composite laminate 4 is the same as the outer shape of the opening 2 on the left side skin of the aircraft.

[0010] Furthermore, the processing depth of the two ring grooves is 2 layers of inner surface layer + inner layer ply is [0 / 45 / 90 / -45 / -90 / 0]5s.

[0011] Furthermore, the material of the aviation foam interlayer 5 is polypropylene plastic foam material EPP.

[0012] Furthermore, the material of the aircraft inner reinforcing pad 3 is LY12-CZ-δ1.5.

[0013] Beneficial effects:

[0014] The invention provides a concentrated impact load protection and reinforcement structure for aircraft skin thin-walled structure, which solves the technical problems caused by the recoil, vibration load and impact load generated by the launch device on the aircraft structure safety, flight safety and other aspects, and meets the requirements of use. The invention has the advantages of simple structure and processability, light weight, safety and reliability, and is a domestic first. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A schematic diagram of the layout of a concentrated impact load protection reinforcement structure for a thin-walled aircraft skin structure;

[0016] Figure 2 It is the A-direction view;

[0017] Figure 3 It is the BB section view;

[0018] Among them: 1. Launch device; 2. Opening on the left side of the aircraft skin; 3. Aircraft inner reinforcement pad; 4. Multi-layer composite laminate; 5. Aviation foam interlayer; 6. Connecting film; 7. Connecting standard part LE-2.6×L rivet. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical scheme and advantages of the implementation of this application clearer, the technical scheme in the implementation of this application will be described in more detail in combination with the drawings in the implementation of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described implementation is a part of the implementation of this application, not all of the implementations. The implementation described below with reference to the drawings is exemplary and is intended to be used to explain this application, and cannot be understood as a limitation on this application. Based on the implementation in this application, all other implementations obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The implementation of this application is described in detail below in combination with the drawings.

[0020] In the description of the present invention, it is necessary to understand that the terms "center", "axial", "vertical", "up", "down", "upper end", "bottom end", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present invention.

[0021] The present application provides a concentrated impact load protection reinforcement structure for the thin-walled structure of the aircraft skin. The aircraft side wall skin generally adopts a thinner skin, and a plate bending frame edge support is arranged inside. In order to meet the requirements of use, the aircraft has a large opening in the aircraft skin with a launch device opened on the aircraft side wall panel. The large opening itself belongs to the stress concentration area of ​​the aircraft structure. In addition, the superposition of various impact loads generated during operation makes this area prone to fatigue damage (such as skin cracks and diffusion) under the action of periodic impact loads, endangering the aircraft structure and flight safety. Therefore, under the premise of ensuring use, it is necessary to adopt measures such as wave absorption and vibration reduction protection reinforcement design for the stress concentration area of ​​the thin-walled structure of the aircraft skin to solve the problem of not only meeting the requirements of use, but also meeting the requirements of aircraft structure and flight safety.

[0022] like Figure 1 As shown, a concentrated impact load protection and reinforcement structure for a thin-walled aircraft skin structure is provided, which includes: a launch device 1, an aircraft left side skin opening 2, an aircraft inner side reinforcement pad 3, a multi-layer composite laminate 4, two aviation foam interlayers 5, a connecting adhesive film 6, and a connecting standard LE-2.6×L rivet 7.

[0023] A concentrated impact load protection and reinforcement structure for aircraft skin thin-walled structure. The first step is to design a multi-layer composite laminate 4, two aviation foam interlayers 5, and a connecting adhesive film 6. The multi-layer composite laminate 4 consists of a surface layer, an inner layer, and two aviation foam interlayers 5. The surface layer is an upper and lower outer layer, each with 2 layers, and the material is 3218Z / SW110Aδ0.11. The inner layer is [0 / 45 / 90 / -45 / -90 / 0]6s, and the material is 3218Z / EW220δ0.22. The production of the multi-layer composite laminate 4 requires a special outer mold. The aircraft outer mold (tool) for the aircraft multi-layer composite laminate 4 is made. The outer shape is the same as the outer shape of the two openings on the left side of the aircraft skin. The surface layer and the inner layer of the multi-layer composite laminate 4 are sequentially laid on the aircraft outer mold and glued with METALSET A4. The composite hydraulic tank is placed to cure and form a multi-layer hyperbolic inclined surface composite laminate with an inner circle thickness of b, an outer circle thickness of a, and a single side length of f. The multi-layer composite laminate 4 is cured and formed by the composite hydraulic tank twice. The inner surface layer and the inner layer are first cured and formed at high temperature for the first time, and then the inner layer is processed by CNC machine tools to form a hyperbolic inclined surface, and then the outer layer is cured at high temperature for the second time to form a multi-layer hyperbolic inclined surface composite laminate 4.

[0024] The multi-layer composite laminate is removed from the layup mold, and two-circle annular grooves are processed on the inner surface of the multi-layer composite laminate (the surface that fits the aircraft skin) on a CNC machine tool. The processing depth of the two-circle annular grooves is [0 / 45 / 90 / -45 / -90 / 0]5s for the inner surface layer 2 layers + the inner layer layup, and the positioning dimensions of the two-circle annular grooves are "c, d (typical), e"; see Figure 3 After the machine tool processing is completed, the two ring grooves on the inner side of the multi-layer composite laminate are bonded and filled with polypropylene plastic foam material (EPP), and the inner shape is repaired to be consistent. The inner surface of the multi-layer composite laminate (the connection surface with the fuselage skin) is bonded with SY-24C-300 adhesive film, and the multi-layer composite laminate 4 is completed and ready for use.

[0025] The second step is to assemble the aircraft. Add an aircraft inner reinforcement pad 3 to the inside of the aircraft skin. The single-side positioning size is g. The reinforcement pad material is LY12-CZ-δ1.5. Connect it to the skin with countersunk rivets to strengthen the aircraft skin opening internally. Position the multi-layer composite laminate 4 with the left skin opening 2 as the center, bond it to the outer surface of the aircraft skin with SY-24C-300 adhesive film, and then connect it to the aircraft skin with 6 connection standard parts LE-2.6×L rivets 7 to strengthen the aircraft skin opening externally. Figure 1 , Figure 2 , Figure 3 .

[0026] Through a concentrated impact load protection reinforcement structure of the aircraft skin thin-walled structure, the stress concentration area of ​​the aircraft thin-walled skin is effectively structurally strengthened, the recoil, vibration load and impact load generated during operation are weakened, and the problem of fatigue damage to the structure of the stress concentration area of ​​the aircraft thin-walled skin is avoided, thereby improving the structural safety and flight safety of the aircraft. The advantages of this design are: the multi-layer composite laminate and polypropylene plastic foam material (EPP) are compression-resistant, buffering, shock-proof, sound-absorbing and heat-insulating materials, which have the characteristics of light specific gravity, good elasticity, high deformation recovery rate, good absorption performance, corrosion resistance, heat resistance and low cost. The present invention has a simple structure and reliable connection, which not only meets the requirements of use, but also ensures the flight safety of the aircraft.

[0027] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A concentrated impact load protection and reinforcement structure for aircraft skin thin-walled structures, characterized in that: include: An aircraft left side skin opening (2), an aircraft inner side reinforcement pad (3), a multi-layer composite laminate (4), an aviation foam interlayer (5), and a connecting adhesive film (6), wherein the multi-layer composite laminate (4) is provided with an annular groove on its surface, and an aviation foam interlayer (5) is provided in the annular groove; the aircraft inner side reinforcement pad (3) is positioned on the inner side of the skin with the left side skin opening (2) as the center, and is connected to the aircraft skin via rivets; the multi-layer composite laminate (4) is positioned on the outer side of the skin with the left side skin opening (2) as the center, and is bonded to the outer surface of the aircraft skin via a connecting adhesive film (6), and is connected to the aircraft skin via rivets, wherein the connecting adhesive film (6) is a SY-24C-300 adhesive film; and the launch device (1) is installed and fixed in the cabin, and then extends out of the cabin through the left side skin opening (2) of the aircraft.

2. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 1, characterized in that: There are two annular grooves, and both are filled with aviation foam interlayers (5).

3. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 2, characterized in that: The surface layers of the multi-layer composite laminate (4) are upper and lower outer layers, each with two layers, and the material is 3218Z / SW110A δ0.

11.

4. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 3, characterized in that: The inner layer of the multi-layer composite laminate (4) is [0 / 45 / 90 / -45 / -90 / 0]6s, and the material is 3218Z / EW220δ0.

22.

5. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 4, characterized in that: The appearance of the multi-layer composite laminate (4) is the same as the appearance of the two openings on the left side skin of the aircraft.

6. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 5, characterized in that: The processing depth of the two ring grooves is 2 layers of inner surface layer + inner layer ply is [0 / 45 / 90 / -45 / -90 / 0]5s.

7. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 6, characterized in that: The aviation foam interlayer (5) is made of polypropylene plastic foam material EPP.

8. The aircraft skin thin-walled structure concentrated impact load protection and reinforcement structure according to claim 7, characterized in that: The material of the aircraft inner side reinforcing pad (3) is LY12-CZ-δ1.5.

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