A topological optimization method for damping arrangement of launch module structure

Abstract

The present application belongs to the technical field of aircraft vibration design, and particularly relates to a method for topological optimization of the damping arrangement of a launch cabin structure, the method mainly comprising: step S1, constructing a dynamic finite element model of the launch system; step S2, applying the shock wave load to the corresponding area of ​​the dynamic finite element model according to the action range of the shock wave load at the outlet of the launch device; step S3, solving the dynamic response of the dynamic finite element model to obtain the acceleration response of the launch cabin structure; step S4, taking the area with relatively large acceleration response as the damping arrangement area; step S5, setting the damping material in the damping arrangement area, and determining the optimal paving area and paving thickness in which the acceleration response of the launch cabin structure is less than the dynamic response setting value, and the weight of the laid damping material is less than the weight setting value. The present application reduces the probability of failure of airborne accessories, and the weight of the additional damping material is the lightest.

Description

Technical Field

[0001] The present application belongs to the technical field of aircraft vibration design, and in particular relates to a topological optimization method for the damping arrangement of a launch cabin structure. Background Art

[0002] Aircraft are usually equipped with large-caliber launchers, which generate high shock waves at the launcher exit when firing. The shock waves act on the fuselage structure and propagate inward, which may cause structural damage and failure of onboard accessories, seriously affecting aircraft safety and the execution of training missions. Publicly available literature shows that domestic and foreign aircraft have varying degrees of launcher vibration problems. For example, the shock wave at the launcher exit of the F-35A aircraft caused damage to the coating near the launcher exit, affecting the aircraft's concealment performance.

[0003] For aircraft equipped with launchers, especially large-caliber launchers, various problems induced by launcher vibrations have received high attention. In order to study the impact of launcher vibration loads on aircraft, reduce the vibration response of aircraft launchers, and thus increase structural fatigue life and reduce equipment failure rates, a large amount of research has been carried out at home and abroad, and significant launcher vibration response control effects have been achieved. Laying damping materials on the structural wall panels to reduce the vibration response of the launcher is one of the commonly used methods, but it is usually laid on the entire launch system. Although the vibration response is reduced, it also increases weight and cost. Summary of the invention

[0004] In order to solve the above problems, the present application provides a launch cabin structure damping arrangement topology optimization method, wherein the launch cabin is located at the rear end of the launch device, and the launch cabin and the launch device together constitute a launch system. The launch cabin structure damping arrangement topology optimization method mainly includes:

[0005] Step S1, constructing a dynamic finite element model of the launch system;

[0006] Step S2, applying the shock wave load to the corresponding area of ​​the dynamic finite element model according to the action range of the shock wave load at the outlet of the launch device;

[0007] Step S3, solving the dynamic response of the dynamic finite element model to obtain the acceleration response of the launch cabin structure;

[0008] Step S4, taking the area with relatively large acceleration response as a damping arrangement area;

[0009] Step S5, setting the damping material in the damping arrangement area, providing an initial damping material laying area and laying thickness, and determining, through a cyclic calculation, an optimal laying area and laying thickness in which the acceleration response of the launch cabin structure is less than a dynamic response setting value and the weight of the laid damping material is less than a weight setting value.

[0010] Preferably, constructing a dynamic finite element model of the launch system includes:

[0011] The launch cabin and its supporting structure are simulated by shell elements, the internal accessories of the launch cabin are simulated by mass point elements, the outlet decompression device and track beam of the launch device are simulated by solid elements, the launch device is simulated by beam elements, and the air inside the launch cabin is simulated by solid elements.

[0012] Preferably, step S1 further comprises:

[0013] Step S11: based on the constructed dynamic finite element model of the launch system, determine the first three frequencies of the launch cabin, and obtain the test frequency of the launch cabin through experiments;

[0014] Step S12: When the error between the first three order frequencies and the test frequency exceeds the frequency setting value, the dynamic finite element model of the launch system is adjusted.

[0015] Preferably, the frequency setting value is 5%.

[0016] Preferably, the adjusting the dynamic finite element model of the launch system includes: adjusting boundary conditions in the dynamic finite element model of the launch system, connection relationships between simulation units, or model mass distribution.

[0017] Preferably, step S3 further comprises:

[0018] The step length of shock response solution is determined according to the action time of the shock wave load at the launch device outlet and the natural frequency of the launch cabin structure. The step length determination principle is to generate at least 5 solution steps within the action time of the shock wave load and the inverse of the first-order natural frequency of the launch cabin structure, and take the minimum step length between the two as the final solution step length.

[0019] Preferably, in step S4, the region with a relatively large acceleration response refers to a region where the acceleration response exceeds the acceleration response of other regions by more than 3 times.

[0020] Preferably, in step S5, setting the damping material includes modifying the material properties of the original structure to properties of a composite material composed of the original structure material and the damping material.

[0021] The present application can greatly reduce the vibration response of the structural launch device, improve the structural fatigue life, reduce the probability of failure of airborne accessories, ensure the smooth execution of training missions, and at the same time achieve the effect of minimizing the weight of the additional damping material. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a preferred embodiment of the launch module structure damping arrangement topology optimization method of the present application.

[0023] Figure 2 This application Figure 1 A schematic diagram of the structure of the transmitting system of the illustrated embodiment.

[0024] Figure 3 This application Figure 1 Schematic diagram of the launch module structure of the illustrated embodiment.

[0025] Among them, 1-launch cabin, 2-launch device, 3-launch cabin support structure, 4-launch cabin internal accessories, 5-exit decompression device, 6-track beam. DETAILED DESCRIPTION

[0026] 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.

[0027] This application provides a launch cabin structure damping arrangement topology optimization method, such as Figure 1 As shown, it mainly includes:

[0028] Step S1: construct a dynamic finite element model of the launch system. Figure 2 and Figure 3The launch cabin 1 is located at the rear end of the launch device 2, and the launch cabin 1, the launch device 2 and other supporting or auxiliary structures together constitute the launch system. The shock wave generated by the projectile launched by the launch device 2 affects the internal accessories 4 of the launch cabin in the launch cabin 1, which is very likely to cause failure of the airborne accessories, so it is necessary to lay damping material on the inner wall of the launch device. In step S1, the present application first constructs a dynamic finite element model of the entire launch system, and subsequently performs a dynamic response analysis of the launch cabin based on the dynamic finite element model to determine the specific laying form of the damping material.

[0029] In some optional embodiments, constructing a dynamic finite element model of the launch system includes:

[0030] The launch cabin 1 and the launch cabin support structure 3 are simulated by shell elements, the internal accessories 4 of the launch cabin are simulated by mass point elements, the outlet decompression device 5 and the track beam 6 of the launch device 2 are simulated by body elements, the launch device 2 is simulated by beam elements, and the air inside the launch cabin is simulated by body elements.

[0031] In the above embodiment, according to the force transmission route and dynamic response analysis purpose, the launch cabin structure and the launch device composed of the launch system are geometrically simplified, and on this basis, a dynamic finite element model is established as follows: Figure 1 shown.

[0032] In some optional implementations, step S1 further includes:

[0033] Step S11: based on the constructed dynamic finite element model of the launch system, determine the first three frequencies of the launch cabin, and obtain the test frequency of the launch cabin through experiments;

[0034] Step S12: When the error between the first three order frequencies and the test frequency exceeds the frequency setting value, the dynamic finite element model of the launch system is adjusted.

[0035] The above embodiment mainly optimizes the dynamic finite element model constructed in step S1. The optimization method is to perform modal analysis on the dynamic finite element model, obtain the main frequencies of the launch module structure and the launch device, and compare them with the experimental analysis results. By adjusting the dynamic model parameters, the frequency errors of the first three frequencies of the launch module structure obtained by finite element analysis and the launch module structure obtained by the experiment are within the set value range, thereby ensuring the accuracy of the dynamic model.

[0036] In some optional implementations, the frequency setting value is 5%. In alternative implementations, the value can also be adjusted to 3%, 7% or 10%, etc.

[0037] In some optional embodiments, adjusting the dynamic finite element model of the launch system includes: adjusting boundary conditions in the dynamic finite element model of the launch system, connection relationships between simulation units, or model mass distribution.

[0038] Step S2: applying the shock wave load to the corresponding area of ​​the dynamic finite element model according to the action range of the shock wave load at the outlet of the launch device.

[0039] After constructing and adjusting the dynamic finite element model, the shock wave will act on the corresponding area of ​​the dynamic finite element model according to the actual shock wave range, that is, the shock wave at the outlet of the launch device will act on the inner wall of the launch cabin at the rear end of the launch device.

[0040] Step S3, solving the dynamic response of the dynamic finite element model to obtain the acceleration response of the launch cabin structure.

[0041] The shock wave acting on the inner wall of the launch cabin causes the launch cabin to vibrate. Therefore, in step S3, the dynamic response generated by the vibration is solved. The main response solved here is the acceleration response. In alternative implementations, the displacement response or dynamic response such as strain can also be solved.

[0042] In some optional implementations, step S3 further includes:

[0043] The step length of shock response solution is determined according to the action time of the shock wave load at the launch device outlet and the natural frequency of the launch cabin structure. The step length determination principle is to generate at least 5 solution steps within the action time of the shock wave load and the inverse of the first-order natural frequency of the launch cabin structure, and take the minimum step length between the two as the final solution step length.

[0044] This embodiment first determines the solution step size of the vibration response generated by the shock wave, usually forming at least 5 steps, based on which the maximum step time can be calculated. Then, the dynamic model is solved using transient response analysis to obtain the acceleration response of the launch cabin structure.

[0045] Step S4: taking the region with relatively large acceleration response as a damping arrangement region.

[0046] In this step, the area with relatively large acceleration response refers to an area where the acceleration response of a certain area is significantly increased relative to that of other areas. For example, in some optional embodiments, the area with relatively large acceleration response refers to an area where the acceleration response is more than 3 times that of other areas.

[0047] Step S5, setting the damping material in the damping arrangement area, providing an initial damping material laying area and laying thickness, and determining, through a cyclic calculation, an optimal laying area and laying thickness in which the acceleration response of the launch cabin structure is less than a dynamic response setting value and the weight of the laid damping material is less than a weight setting value.

[0048] In some optional implementations, in step S5, setting the damping material includes modifying the material properties of the original structure to properties of a composite material composed of the original structure material and the damping material.

[0049] This embodiment is usually programmed through MATLAB to set the damping material laying area, and randomly modify the unit thickness attribute in the area with larger dynamic response within a certain range according to the laying area, and solve the dynamic response to obtain the minimum value of the dynamic response under a certain laying area, and then determine the damping material laying plan.

[0050] This application conducts an optimization layout analysis of damping materials for the launch module structure and provides a damping material layout plan, thereby having the advantage of the lightest additional weight while maintaining the same vibration response control effect of the launch device.

[0051] 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 method for topological optimization of the damping arrangement of a launch module structure, wherein: The launch cabin (1) is located at the rear end of the launch device (2), and the launch cabin (1) and the launch device (2) together constitute a launch system, characterized in that the launch cabin structure damping arrangement topology optimization method comprises: Step S1, constructing a dynamic finite element model of the launch system; Step S2, applying the shock wave load to the corresponding area of ​​the dynamic finite element model according to the action range of the shock wave load at the outlet of the launch device; Step S3, solving the dynamic response of the dynamic finite element model to obtain the acceleration response of the launch cabin structure; Step S4, taking the area with relatively large acceleration response as a damping arrangement area; Step S5, setting the damping material in the damping arrangement area, providing an initial damping material laying area and laying thickness, and determining, through cyclic calculation, an optimal laying area and laying thickness in which the acceleration response of the launch cabin structure is less than a dynamic response setting value and the weight of the laid damping material is less than a weight setting value; Among them, the dynamic finite element model of the launch system includes: The launch cabin (1) and the launch cabin support structure (3) are simulated by shell elements, the internal accessories (4) of the launch cabin are simulated by mass point elements, the outlet pressure relief device (5) and the track beam (6) of the launch device (2) are simulated by solid elements, the launch device (2) is simulated by beam elements, and the air inside the launch cabin is simulated by solid elements; Step S3 further comprises: According to the action time of the shock wave load at the launch device exit and the natural frequency of the launch cabin structure, the step length of the shock response solution is determined. The principle of determining the step length is to generate at least 5 solution steps within the action time of the shock wave load and the inverse of the first-order natural frequency of the launch cabin structure, and take the minimum step length of the two as the final solution step length. Based on this, the maximum step length is calculated, and then the transient response analysis is used to solve the dynamic model to obtain the acceleration response of the launch cabin structure; In step S4, the region with a relatively large acceleration response refers to a region where the acceleration response is more than three times that of other regions.

2. The launch module structure damping arrangement topology optimization method according to claim 1, characterized in that: Step S1 further comprises: Step S11: based on the constructed dynamic finite element model of the launch system, determine the first three frequencies of the launch cabin, and obtain the test frequency of the launch cabin through experiments; Step S12: When the error between the first three order frequencies and the test frequency exceeds the frequency setting value, the dynamic finite element model of the launch system is adjusted.

3. The launch module structure damping arrangement topology optimization method according to claim 2, characterized in that: The frequency setting value is 5%.

4. The launch module structure damping arrangement topology optimization method according to claim 2, characterized in that: Adjusting the dynamic finite element model of the launch system includes: adjusting boundary conditions in the dynamic finite element model of the launch system, connection relationships between simulation units, or model mass distribution.

5. The launch module structure damping arrangement topology optimization method according to claim 1, characterized in that: In step S5, setting the damping material includes modifying the material properties of the original structure to the properties of a composite material composed of the original structure material and the damping material.

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