Simulation analysis method for structural response of aviation products under point source impact loads

Abstract

The present invention provides a simulation analysis method for the structural response of aviation products under the action of point source impact loads, which includes: constructing a point source impact load simulation model: simulating the formation of point source impact loads, and calculating the propagation of point source impact loads; constructing a coupling model of impact loads and aviation product structural responses: constructing a point source impact load flow field model, constructing a finite element model for calculating the transient response of aviation products, and defining the coupling surface of the point source impact load model; iterating the parameters of the coupling model of impact loads and aviation product structural responses, calculating the structural response of aviation products, and obtaining the pressure simulation results of the structural response of aviation products. The present invention is based on detonation theory, equivalently simulates the formation and propagation of point source impact loads, fully considers the timing characteristics of point source impact loads, and is corrected in combination with test data. It has strong engineering practicality and credible calculation results.

Description

Technical Field

[0001] The invention belongs to the technical field of mechanical simulation, in particular to a simulation analysis method for the structural response of an aviation product under the action of a point source impact load. Background Art

[0002] Aviation products include hydraulic and pneumatic equipment such as actuators, valves, pumps, valves, hydraulic locks, electromechanical equipment such as electromechanical actuators, generators, electric seats, and motion mechanisms such as locking mechanisms, operating mechanisms, and retraction mechanisms. They are widely used in key airborne systems such as flight control, fuel, hydraulics, environmental control, and landing gear that directly affect aircraft safety and missions.

[0003] The environmental loads borne by the above-mentioned aviation products are diverse in type and complex in form. Among them, the impact loads that spread from point sources to the surroundings and act on the surface of the structure have a greater impact on the product and are difficult to simulate. Point source impact loads often develop into a forward-moving shock wave, which acts on the surface of the structure, causing rapid and severe bending deformation of the structural shell, and various types of stress waves are stimulated to propagate into the structure, causing severe vibration of the product structure and damage to internal equipment. Point source impact loads are the main difficulty in accurately calculating the structural response of aviation products. There are three reasons: First, after the point source load spreads, it continues to act on the surface of the product structure. The energy gradually dissipates after the load propagates over a certain distance and time. Therefore, there is a time difference in the loads received at different positions on the surface of the structure; second, the point source load undergoes continuous energy attenuation during the propagation process. This energy attenuation is a continuous function rather than a segmented point value, and its attenuation rate is specific; third, after the point source impact load acts on the surface of the product, reflection occurs, and there is an interaction between the load and the structure. When considering the load propagation, the response of the structure must be considered. Therefore, in order to accurately calculate the structural response of aviation products after being subjected to gunfire shock waves, it is urgent and necessary to seek a simulation analysis method for the structural response of aviation products under point source impact loads to determine the coupling relationship between product impact loads and structural responses. Summary of the invention

[0004] In view of the defects in the above-mentioned prior art, the present invention proposes a simulation analysis method for the structural response of aviation products under the action of point source impact loads. The method includes constructing a point source impact load simulation model: simulating the formation of point source impact loads, and calculating the propagation of point source impact loads; constructing a coupling model of impact loads and aviation product structural responses: constructing a point source impact load flow field model, constructing a finite element model for calculating the transient response of aviation products, and defining the coupling surface of the point source impact load model; iterating the parameters of the coupling model of impact loads and aviation product structural responses, calculating the structural response of aviation products, and obtaining the pressure simulation results of the structural response of aviation products. Based on the detonation theory, the present invention equivalently simulates the formation and propagation of point source impact loads, fully considers the timing characteristics of point source impact loads, and makes corrections based on experimental data. It has strong engineering practicality and reliable calculation results.

[0005] The present invention provides a simulation analysis method for the structural response of an aviation product under a point source impact load, which comprises the following steps:

[0006] S1. Construct a point source impact load simulation model: simulate the formation of point source impact load and calculate the propagation of point source impact load;

[0007] S11. Based on the detonation theory and the Chapman-Hugonio CJ model, the point source impact load formation is simulated; specifically:

[0008] S111, establish the Rankine-Hugoniot relationship;

[0009] S112. Using the Jones-Wilkins-Lee JWL equation of state for detonation products, describe the pressure value P of the detonation wave during the process of high-temperature and high-pressure chemical substances expanding and transforming into various gas products in the point source formation area. s :

[0010]

[0011] Wherein, V represents the relative specific volume of the medium of the point source; A, B, R1, R2, ω represent the first, second, third, fourth and fifth state equation parameters respectively; E represents the specific internal energy of the medium of the point source, and e is the natural logarithm;

[0012] S113. Using the energy similarity law equivalent theory, calculate the equivalent load source mass W T for:

[0013]

[0014] Where W1 represents the actual load source mass; Q1 represents the unit mass explosion heat of the actual load source; Q T It represents the explosion heat per unit mass of the equivalent load source;

[0015] S12. Calculate the propagation of point source impact load based on the ideal gas state equation:

[0016]

[0017] Where P represents air pressure; γ represents polytropic index; ρ represents medium density; ρ0 represents wavefront medium density;

[0018] S2. Constructing the coupling model of impact load and aviation product structural response: constructing the flow field model of point source impact load, constructing the finite element model for transient response calculation of aviation products, and defining the coupling surface of the point source impact load model;

[0019] S3. Iterate the parameters of the coupling model of impact load and aviation product structure response to calculate the structural response of the aviation product: by combining simulation and experiment, repeatedly iterate the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω in the Jones-Wilkins-Lee JWL state equation in the coupling model of impact load and aviation product structure response, determine the coupling model of impact load and aviation product structure response with the best accuracy of structural response calculation results, and calculate the pressure simulation results of aviation product structure response; specifically:

[0020] S31, determining the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω through iterative model parameter iteration of the impact load and the aviation product structure response;

[0021] S32. Based on the initial energy and the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, and with the help of the impact load and aviation product structural response coupling model, the pressure simulation results of the aviation product structural response are obtained.

[0022] Further, the step S2 specifically includes the following steps:

[0023] S21. Constructing the flow field model of point source impact load: In the flow field geometry model, the physical properties of the point source impact load formation area and the external propagation air domain are defined by using the Jones-Wilkins-Lee JWL state equation and the ideal gas state equation, and the grid contact between the point source impact load formation area and the external propagation air domain is set to ensure the transfer of numerical calculation results at the junction of the point source impact load formation area and the external propagation air domain;

[0024] S22. Construct a finite element model for transient response calculation of aviation products: With the help of finite element model construction method, establish a finite element model of aviation products, and set the grid of the coupling surface between the aviation product structure and the external propagation air domain to be consistent to ensure the correctness of the coupling surface data transmission;

[0025] S23. Define the coupling surface of the point source impact load model: select the surfaces in contact between the aviation product structure surface and the external propagation air domain as coupling surfaces, select the coupling surface penalty function type, set the number of coupling points, and complete the construction of the coupling model of impact load and aviation product structure response.

[0026] Preferably, the step S31 specifically includes the following steps:

[0027] S311. Conduct a point source impact load test experiment to obtain experimental control data;

[0028] S312, determining a set of initial empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, substituting them into the impact load and aviation product structural response coupling model for simulation calculation to obtain pressure data;

[0029] S313, comparing the pressure data obtained by simulation with the experimental control data, and modifying the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω;

[0030] S314, repeatedly execute step S313. When the pressure data calculated by the simulation of the coupling model of impact load and aviation product structure response is compared with the preset range value of the experimental control data, it is considered that the empirical value at this time is correct, and the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω are determined.

[0031] Preferably, the relative specific volume V of the medium in step S112 is expressed as:

[0032]

[0033] Where v represents the specific volume of the medium and v0 represents the initial specific volume of the medium and

[0034] Preferably, in step S111, the internal chemical reaction process of the detonation is ignored, and it is assumed that all physical states remain homogeneous before and after the explosion; in step S113, it is assumed that the shock wave formation principle and propagation process of different types of load sources are the same, and from the perspective of specific internal energy, it is assumed that the total energy of the load sources is equal and the explosion scale is similar, and the actual load source mass is converted into the equivalent load source mass.

[0035] Preferably, in step S12, the ideal gas state equation is used to describe the shock wave propagation process in the aviation product installation environment.

[0036] Preferably, the medium in step S12 is air.

[0037] Compared with the prior art, the technical effects of the present invention are:

[0038] 1. The present invention designs a simulation analysis method for the structural response of aviation products under point source impact loads, provides a feasible engineering method for simulating point source impact loads of aviation products, and gives an equivalent simulation method for point source impact loads, a method for determining the equivalent mass of point source loads, and a simulation analysis method for coupling calculation of point source impact loads and structural responses.

[0039] 2. The simulation analysis method of the structural response of aviation products under point source impact loads designed in the present invention provides a point source impact load simulation scheme with great engineering practicality, which opens up a good path for engineering applications; the timing characteristics of point source impact loads are fully considered, so that the simulation of load input has a very high accuracy; the point source impact load simulation method used is combined with test data for correction, thereby ensuring that the calculation results have a high degree of credibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Other features, objects and advantages of the present application will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings.

[0041] Figure 1 It is a flow chart of the simulation analysis method of the aviation product structure response under the point source impact load of the present invention;

[0042] Figure 2 It is a schematic diagram of the propagation process of the detonation wave front of the present invention;

[0043] Figure 3 is a schematic diagram of the setting of the air domain and the product boundary in a specific embodiment of the present invention;

[0044] Figure 4a It is a calculation result diagram of 0.4ms flow field, product surface pressure, and wall panel equivalent stress of the calculation result of the coupling model of impact load and aviation product structure response in a specific embodiment of the present invention;

[0045] Figure 4b It is a calculation result diagram of 1ms flow field, product surface pressure, and wall panel equivalent stress of the calculation result of the coupling model of impact load and aviation product structure response in a specific embodiment of the present invention;

[0046] Figure 4c It is a calculation result diagram of 3ms flow field, product surface pressure, and wall panel equivalent stress of the calculation result of the coupling model of impact load and aviation product structure response in a specific embodiment of the present invention;

[0047] Figure 5 It is an experimental stress collection point in a specific embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present application will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the relevant invention, rather than to limit the invention. It should also be noted that, for ease of description, only the parts related to the relevant invention are shown in the accompanying drawings.

[0049] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0050] Figure 1 The present invention shows a simulation analysis method for the structural response of an aviation product under a point source impact load, the method comprising the following steps:

[0051] S1. Construct a point source impact load simulation model: simulate the formation of point source impact load and calculate the propagation of point source impact load.

[0052] In the point source impact load simulation problem, the following assumptions are made:

[0053] a) Ignore the air compression and temperature rise process before the load source and assume that the impact energy is released instantly;

[0054] b) The gas inside the load source acts as an ideal medium and obeys the gas state equation.

[0055] It is assumed that the simulation model of point source impact load consists of two parts: formation and propagation: the point source load formation area and the external propagation air domain. The point source load formation area adopts the simulated load formation process of explosive explosion. The explosive forms high-temperature and high-pressure gas through the detonation process to squeeze the external air, forming a propulsion pressure wave in the external propagation air domain. The point source load formation causes the generation of shock waves, which is mainly determined by the load source size, parameters and detonation position; the propagation process is mainly determined by the contact mode between air and load source, medium density and boundary conditions. The equivalent load source parameters and size greatly affect the shock wave intensity, and the contact mode between the load source and the air domain in the simulation affects the shock wave waveform. The load source is controlled by the typical load source JWL equation, and the external air domain is controlled by the ideal gas linear state equation.

[0056] S11. Based on detonation theory and Chapman-Hugoniot CJ model, point source impact load formation is simulated.

[0057] S111. Assuming that the point source load forms a detonation-like process, the physical property change of the point source load is completed by mutation on the detonation surface, such as Figure 2As shown. Ignoring the internal chemical reaction process of the detonation and assuming that all physical states remain homogeneous before and after the explosion, the Rankine-Hugoniot relationship is expressed as:

[0058] ρ(Du)=ρ0(D-u0) (1)

[0059] ρ(Du) 2 +ρ=ρ0(D-u0) 2 +p0 (2)

[0060]

[0061] Among them, D represents the shock wave velocity; u represents the medium movement velocity; u0 represents the wavefront medium movement velocity; p represents the medium pressure; p0 represents the wavefront medium pressure; ρ represents the medium density; ρ0 represents the wavefront medium density; E represents the medium specific internal energy; E0 represents the wavefront medium specific internal energy.

[0062] If the four state quantities before the wave are known, all state quantities after the shock wave can be solved by supplementing a state equation and determining one of the four unknown quantities D, p, ρ, and u.

[0063] S112. Using the Jones-Wilkins-Lee JWL equation of state for detonation products, describe the pressure value P of the detonation wave during the process of high-temperature and high-pressure chemical substances expanding and transforming into various gas products in the point source formation area. s :

[0064]

[0065] Among them, V represents the relative specific volume of the medium; A, B, R1, R2, ω represent the first, second, third, fourth and fifth state equation parameters respectively. It is generally determined by cylinder test and simulation. Soures et al. of LLNL Laboratory in the United States pointed out through a large number of experiments that the values ​​of A, B, R1, R2, ω should satisfy a certain relationship and be within a certain range. According to the test results, generally A = (10 ~ 50) B, R1 = 4 ~ 7, R2 = 0.8 ~ 2, ω = 0.25 ~ 0.6.

[0066] The relative specific volume V of the medium is expressed as:

[0067]

[0068] Where v represents the specific volume of the medium and v0 represents the initial specific volume of the medium and

[0069] In one embodiment, the preferred medium is air.

[0070] S113. Since it is assumed that the point source load forms a similar detonation process, the total detonation energy needs to be equivalent to the parameters of the known load source in the actual application model in order to obtain the initial simulation parameters. With the help of the energy similarity law equivalence theory, it is assumed that the shock wave formation principle and propagation process of different types of load sources are the same. From the perspective of specific internal energy, it is assumed that the total energy of the load source is equal and the explosion scale is similar. The actual load source mass is converted into the equivalent load source mass, and the equivalent load source mass W is calculated. T for:

[0071]

[0072] Where W1 represents the actual load source mass; Q1 represents the unit mass explosion heat of the actual load source; Q T It represents the explosion heat per unit mass of the equivalent load source.

[0073] S12. Use the ideal gas state equation to describe the shock wave propagation process in the installation environment of aviation products and calculate the point source shock load propagation:

[0074]

[0075] Wherein, P represents air pressure; γ represents polytropic index.

[0076] S2. Construct a coupling model of impact load and structural response of aviation products: construct a flow field model of point source impact load, construct a finite element model for transient response calculation of aviation products, and define the coupling surface of the point source impact load model.

[0077] S21. Construct a point source impact load flow field model: In the flow field geometry model, the physical properties of the point source impact load formation area and the external propagation air domain are defined with the help of the Jones-Wilkins-Lee JWL state equation and the ideal gas state equation, and the grid contact between the point source impact load formation area and the external propagation air domain is set to ensure the transmission of numerical calculation results at the junction of the point source impact load formation area and the external propagation air domain.

[0078] S22. Construct a finite element model for transient response calculation of aviation products: With the help of finite element model construction method, a finite element model of aviation products is established. At the same time, the grid of the coupling surface between the aviation product structure and the external propagation air domain is set consistent to ensure the correctness of the coupling surface data transmission.

[0079] S23. Define the coupling surface of the point source impact load model: select the surfaces in contact between the aviation product structure surface and the external propagation air domain as coupling surfaces, select the coupling surface penalty function type, set the number of coupling points, and complete the construction of the coupling model of impact load and aviation product structure response.

[0080] S3. Iterate the parameters of the coupling model of impact load and structural response of aviation products to calculate the structural response of aviation products: By combining simulation with experiment, the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω in the Jones-Wilkins-Lee JWL state equation are repeatedly iterated in the coupling model of impact load and structural response of aviation products to determine the coupling model of impact load and structural response of aviation products with the best accuracy of structural response calculation results, and calculate the pressure simulation results of the structural response of aviation products.

[0081] S31. After iterating the parameters of the coupling model of impact load and aviation product structure response, the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω are determined.

[0082] S311. Conduct a point source impact load test experiment to obtain experimental control data.

[0083] S312. Determine a set of initial empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, substitute them into the impact load and aviation product structural response coupling model for simulation calculation to obtain pressure data.

[0084] S313. Compare the pressure data obtained by simulation with the experimental control data, and modify the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω.

[0085] S314, repeatedly execute step S313. When the pressure data calculated by the simulation of the impact load and aviation product structural response coupling model is compared with the experimental control data and meets the preset range value, it means that the pressure data calculated by the simulation is well compared with the experimental control data. It is considered that the empirical value at this time is correct, and the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω are determined.

[0086] S32. Based on the initial energy and the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, and with the help of the impact load and aviation product structural response coupling model, the pressure simulation results of the aviation product structural response are obtained.

[0087] In a specific embodiment, the exterior of an aviation product is subjected to the impact of a point source load shock wave. In order to obtain the structural response of the aviation product, the point source impact load simulation method of the present invention is used to obtain the external load, and then a coupling model of the impact load of the aviation product and the structural response of the aviation product is constructed, and the structural response calculation is completed.

[0088] S1. Construct a point source impact load simulation model.

[0089] When iteratively calculating the parameters of the point source impact load simulation model, the Jones-Wilkins-Lee JWL state equation parameters of TNT explosives were used as the initial values, and the initial shock wave velocity D was determined to be 689000 mm / s, the wavefront medium pressure p0 was 180 MPa, the wavefront medium specific internal energy E0 was 800 mJE0, and the medium density ρ was 1.63e-9 t / m 3 According to the laboratory experience, the parameters of the Jones-Wilkins-Lee JWL state equation were selected as A=30000MPa, B=2000MPa, R1=4.1, R2=1.1, and ω=0.35.

[0090] Based on the energy similarity law equivalence theory, the actual load source mass W1 = 0.135kg, the unit mass explosion heat Q1 = 2500kJ·kg -1 and the unit mass explosion heat Q of the equivalent load source of TNT T =4190 kJ kg -1 Substitute into formula (5) to convert the equivalent load source mass W of a certain aviation product point source impact load relative to TNT T :

[0091]

[0092] The air in the external propagation air domain adopts the ideal state equation, where γ is taken as 1.4, the initial air pressure P = 100 kPa, and the wavefront medium density ρ0 = 1.0 kg / m 3 .

[0093] S2. Construct a coupling model between impact load and structural response of aviation products.

[0094] After the point source load shock wave is formed, the pressure peak measured at a distance 40 times the size of the load outlet is still higher than the normal atmospheric pressure value, so the flow field at the front of the load source should cover a distance 40 times the size of the outlet; although the jet shock wave has strong directional characteristics, the rear end of the load outlet is still affected by the shock wave, so the rear end area of ​​the load source should also be covered. Therefore, a certain height range outside the right wall of the entire aviation product structure, that is, the area surrounding the load source, is selected as the point source shock load propagation area.

[0095] Computational solid mechanics and computational fluid dynamics use the Lagrangian column method and the Euler column method respectively. The inconsistency of the calculation column method makes it difficult to unify the two domains during coupled calculations. The characteristic of the Lagrangian method in numerical calculations is that there is no material flow in the grid, and the deformation of the grid and the material surface is a follower relationship. The spatial discretization of the LS-DYNA program mainly uses the Lagrangian method, in which the grid and the structure are coincident, and the grid deforms with the deformation of the structure. It is very friendly to solve medium-degree deformation problems, but when the material undergoes large deformation, it is easy to cause the calculation to fail to converge due to excessive distortion of the grid. Unlike the Lagrangian method, the grid of the Euler method does not move with the deformation, and only the material moves relative to the grid. This leads to the need to divide the grid unit into small enough units in order to accurately capture the deformation of the material, which greatly increases the cost of numerical analysis. The ALE grid combines the advantages of the two methods, establishes a coincident space point grid and an attached follower grid, and when the ALE grid is used in the calculation of the Euler format, several steps such as grid deformation calculation, material transport solution and mapping to the space grid must be performed separately.

[0096] LS-DYNA is used to establish a flow field model after the point source impact load is formed and propagated. The flow field model contains a cylindrical load source and an air domain that wraps the outer wall of the aviation product. There is a certain distance between the load source and the outer wall of the aviation product. When the aviation product is meshed, in order to ensure that the detonation energy is transferred to the air domain, the grids on the contact surface between the load source and the air are required to be completely consistent, and the node fusion method is used to connect them. Finally, 336 equivalent load source units and 211,704 air units are divided. In order to cooperate with the model calculation of fluid-solid coupling, the load source and air units here are respectively controlled by ALE dynamic mesh, which is set by the *ALE_MULTI-MATERIAL_GROUP command. The equivalent explosive and air are considered as continuous media. The equivalent explosive part uses the *MAT_HIGH_EXPLOSIVE_BURN No. 8 material model in the DYNA material library, and the JWL state equation in *EOS_JWL is used to describe the detonation products. The air part uses the *MAT_NULL material model No. 9 in the DYNA material library and is controlled by the linear polynomial equation EOS_LINEAR_POLYNOMIAL.

[0097] After completing the meshing of the aviation product geometry model in Hypermesh, the mesh model is imported into LS-DYNA. After assigning material properties according to the material grades of each part, the coupling interface with the impact load is set. One side of the air domain completely overlaps with the right wall of the aviation product as the fluid-solid coupling interface. The other five surfaces of the air domain will be regarded as free flow surfaces and set as non-reflection boundaries, such as Figure 3 As shown in the figure, six-direction freedom constraints are set at the mounting bracket of the aviation product. So far, the construction of the coupling model of impact load and aviation product structural response is completed.

[0098] S3. Iterate the model parameters of the coupling between impact load and aviation product structural response to calculate the aviation product structural response.

[0099] In order to simulate the directionality of energy transmitted from the equivalent load source to the air, the load source and the air domain are connected to the grid using a single-sided contact method.

[0100] In order to fully develop the detonation pressure and ensure that the pressure value on the outside of the front end of the load source is relatively uniform after detonation, the midpoint of the wall of the load source cylinder on the opposite side of the shock wave is taken as the detonation point. The coordinates of this point are input using the *INITIAL_DETONATION command, and the detonation is set to 0. The calculation is started after setting the calculation time of 10s. The calculation results are as follows: Figures 4a to 4c shown.

[0101] The physical test is carried out to simulate the impact environment of the aviation product when it is used on the aircraft, and the structural stress of the aviation product is obtained. Six points on the surface shell of the aviation product are selected to attach strain rosettes to measure the strain value. The measurement point positions are as follows: Figure 5 The experimental measurement and simulation calculation are both time series curves of strain values. Here we mainly focus on the deviation of the maximum strain value. The data comparison is shown in Table 1.

[0102]

[0103] Table 1

[0104] The test data show that the overall structural response of aviation products is too small, indicating that the simulated value of the point source impact load is too small. The high-pressure influencing parameters in the shock wave model should be adjusted to make the value of the impact load closer to the real value. After several parameter adjustments and iterative calculations, the final values ​​of the parameters of the Jones-Wilkins-Lee JWL state equation are A=30000MPa, B=700MPa, R1=4.1, R2=1.1, ω=0.35. The comparison between the simulation and the test is shown in Table 2. The data shows that the average error between the current simulation results and the test results is 11%, which is much lower than the requirement of 20% error between simulation and actual measurement in general engineering. It verifies the feasibility and accuracy of the simulation analysis method of the structural response of aviation products based on point source impact load simulation of the present invention.

[0105]

[0106] Table 2

[0107] The present invention designs a simulation and analysis method for the structural response of an aviation product under a point source impact load, provides a feasible engineering method for simulating point source impact loads of aviation products, and provides an equivalent simulation method for point source impact loads, a method for determining the equivalent mass of point source loads, and a simulation and analysis method for coupling calculation of point source impact loads and structural responses; provides a point source impact load simulation scheme with great engineering practicality, and opens up a good path for engineering applications; fully considers the timing characteristics of point source impact loads, so that the simulation of load input has a very high degree of accuracy; the point source impact load simulation method used is corrected in combination with test data, thereby ensuring that the calculation results have a high degree of credibility.

[0108] Finally, it should be noted that the above embodiments are only intended to illustrate rather than limit the technical solutions of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that the present invention can still be modified or replaced by equivalents. Any modification or partial replacement that does not depart from the spirit and scope of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A simulation analysis method for the structural response of aviation products under point source impact loads, characterized in that: It includes the following steps: S1. Construct a point source impact load simulation model: simulate the formation of point source impact load and calculate the propagation of point source impact load; S11. Based on the detonation theory and the Chapman-Hugonio CJ model, the point source impact load formation is simulated; specifically: S111, establish the Rankine-Hugoniot relationship; S112. Using the Jones-Wilkins-Lee JWL equation of state for detonation products, describe the pressure value P of the detonation wave during the process of high-temperature and high-pressure chemical substances expanding and transforming into various gas products in the point source formation area. s : Wherein, V represents the relative specific volume of the medium of the point source; A, B, R1, R2, ω represent the first, second, third, fourth and fifth state equation parameters respectively; E represents the specific internal energy of the medium of the point source, and e is the natural logarithm; S113. Using the energy similarity law equivalent theory, calculate the equivalent load source mass W T for: Where W1 represents the actual load source mass; Q1 represents the unit mass explosion heat of the actual load source; Q T It represents the explosion heat per unit mass of the equivalent load source; S12. Calculate the propagation of point source impact load based on the ideal gas state equation: Where P represents air pressure; γ represents polytropic index; ρ represents medium density; ρ0 represents wavefront medium density; S2. Constructing the coupling model of impact load and aviation product structural response: constructing the flow field model of point source impact load, constructing the finite element model for transient response calculation of aviation products, and defining the coupling surface of the point source impact load model; S3. Iterate the parameters of the coupling model of impact load and aviation product structure response to calculate the structural response of the aviation product: by combining simulation and experiment, repeatedly iterate the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω in the Jones-Wilkins-Lee JWL state equation in the coupling model of impact load and aviation product structure response, determine the coupling model of impact load and aviation product structure response with the best accuracy of structural response calculation results, and calculate the pressure simulation results of aviation product structure response; specifically: S31, determining the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω through iterative model parameter iteration of the impact load and the aviation product structure response; S32. Based on the initial energy and the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, and with the help of the impact load and aviation product structural response coupling model, the pressure simulation results of the aviation product structural response are obtained.

2. The simulation analysis method for the structural response of aviation products under point source impact load according to claim 1 is characterized in that: The step S2 specifically includes the following steps: S21. Constructing the flow field model of point source impact load: In the flow field geometry model, the physical properties of the point source impact load formation area and the external propagation air domain are defined by using the Jones-Wilkins-Lee JWL state equation and the ideal gas state equation, and the grid contact between the point source impact load formation area and the external propagation air domain is set to ensure the transfer of numerical calculation results at the junction of the point source impact load formation area and the external propagation air domain; S22. Construct a finite element model for transient response calculation of aviation products: With the help of finite element model construction method, establish a finite element model of aviation products, and set the grid of the coupling surface between the aviation product structure and the external propagation air domain to be consistent to ensure the correctness of the coupling surface data transmission; S23. Define the coupling surface of the point source impact load model: select the surfaces in contact between the aviation product structure surface and the external propagation air domain as coupling surfaces, select the coupling surface penalty function type, set the number of coupling points, and complete the construction of the coupling model of impact load and aviation product structure response.

3. The simulation analysis method for the structural response of aviation products under point source impact load according to claim 1 is characterized in that: The step S31 specifically includes the following steps: S311. Conduct a point source impact load test experiment to obtain experimental control data; S312, determining a set of initial empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω, substituting them into the impact load and aviation product structural response coupling model for simulation calculation to obtain pressure data; S313, comparing the pressure data obtained by simulation with the experimental control data, and modifying the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω; S314, repeatedly executing step S313, when the pressure data calculated by the simulation of the impact load and the aviation product structural response coupling model is compared with the experimental control data and meets the preset range value, the empirical values ​​of the first, second, third, fourth and fifth state equation parameters A, B, R1, R2, ω are determined.

4. The simulation analysis method for the structural response of aviation products under point source impact loads according to claim 1 is characterized in that: The relative specific volume V of the medium in step S112 is expressed as: Where v represents the specific volume of the medium and v0 represents the initial specific volume of the medium and 5. The simulation analysis method for the structural response of aviation products under point source impact loads according to claim 1 is characterized in that: In step S111, the internal chemical reaction process of the detonation is ignored, and it is assumed that all physical states remain homogeneous before and after the explosion; in step S113, it is assumed that the shock wave formation principle and propagation process of different types of load sources are the same, and from the perspective of specific internal energy, it is assumed that the total energy of the load sources is equal and the explosion scale is similar, and the actual load source mass is converted into the equivalent load source mass.

6. The simulation analysis method for the structural response of aviation products under point source impact loads according to claim 1 is characterized in that: In step S12, the ideal gas state equation is used to describe the shock wave propagation process in the aviation product installation environment.

7. The simulation analysis method for the structural response of aviation products under point source impact loads according to claim 1 is characterized in that: The medium in step S12 is air.

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