A method for optimizing the anti-ballistic performance of composite materials based on stochastic constitutive model

Abstract

The present invention relates to the field of composite materials, and particularly to an optimized design method for the anti-ballistic performance of composite materials based on a stochastic constitutive model, comprising the following steps: preparing a composite material specimen to conduct a ballistic impact test, and recording the incident velocity V of the specimen i - residual velocity V r ; establishing a dynamic damage constitutive model for the composite material, conducting a ballistic impact numerical simulation in comparison with the test, and verifying the rationality of the reference value of the constitutive model parameters by comparing the test results; establishing a stochastic dynamic damage constitutive model, and calibrating the inhomogeneous parameters of each test specimen through numerical simulation #imgabs0# This design method can optimize the anti-ballistic performance of composite materials by establishing a stochastic dynamic damage constitutive model for composite materials and using the constitutive model through secondary development. This method can reduce the dependence on experience in the design process, reduce the number of penetration tests and costs, and optimize the design of fiber-reinforced composite material plates that meet the anti-ballistic index and reliability requirements.

Description

Technical Field

[0001] The invention relates to the field of composite materials, and in particular to a composite material anti-ballistic performance optimization design method based on a random constitutive model. Background Art

[0002] Composite materials are new materials composed of two or more materials, which are widely used due to their excellent physical and chemical properties. Composite materials are lightweight and high-strength, and have great advantages in anti-collision, bulletproof and explosion-proof. They are widely used in many fields such as automobile manufacturing, aircraft manufacturing, and engineering protection. The anti-ballistic performance design of composite materials is an important part of composite material protection design. With the continuous application of composite materials in major engineering facilities and equipment, the actual demand for the anti-ballistic performance design of composite materials continues to emerge.

[0003] The thickness of composite materials has a great influence on the anti-ballistic performance. Generally speaking, the thicker the composite material, the stronger its anti-ballistic performance. However, as the thickness increases, the weight and manufacturing cost of the composite material will also increase significantly. Therefore, minimizing the thickness of the composite material while meeting the anti-ballistic performance requirements is the main content of the anti-ballistic performance optimization design of composite materials. There are two main links in the design of composite materials. One is to combine theory and experience to design and manufacture composite panels, and the other is to conduct experimental verification and iteratively optimize the design scheme based on the experimental results. This design process is highly dependent on the designer's experience. Under unfavorable conditions, it may take multiple iterations to design a composite material that meets the requirements. There are problems of high cost and slow speed. In addition, when optimizing the anti-ballistic performance design, the reliability of the material's anti-ballistic performance must often be fully considered. The semi-empirical method cannot be quantified in terms of reliability, and the experimental method is expensive, which brings huge challenges to the optimization design of composite material anti-ballistic performance. Summary of the invention

[0004] The purpose of the present invention is to provide a method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model. The design method establishes a random dynamic damage constitutive model of the composite material and uses the constitutive model to optimize the anti-ballistic performance of the composite material through secondary development. The method can reduce the dependence of the design process on experience, reduce the number and cost of penetration tests, and optimize the design of a fiber-reinforced composite material plate that meets the anti-ballistic index and reliability requirements.

[0005] In order to achieve the above object, the present invention adopts the following technical solution:

[0006] A method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model comprises the following steps:

[0007] S1. Prepare composite material specimens for ballistic impact tests and record the incident velocity V of the specimens. i- Remaining speed V r ;

[0008] S2. Establish a dynamic damage constitutive model for composite materials, conduct numerical simulation of ballistic impact with control tests, and verify the rationality of the baseline values ​​of constitutive model parameters by comparing test results;

[0009] S3. Establish a random dynamic damage constitutive model and calibrate the heterogeneous parameters of each test specimen through numerical simulation

[0010] S4, establishing the probability density function of the anti-ballistic performance reliability parameter φ;

[0011] S5. Determine the reliability parameter φ of the ballistic performance according to the reliability requirements of the ballistic design x and the constitutive model heterogeneity parameters

[0012] S6. Carry out numerical simulation according to the requirements of anti-ballistic index and optimize the design of the thickness of the composite material plate.

[0013] Further, in step S2, the strength of the dynamic damage constitutive model is f, the Young's modulus is E, and the dynamic enhancement factor is used to consider the strain rate effect. The dynamic enhancement factor of elastic modulus is DIF c , the intensity dynamic enhancement factor is DIF f , the constitutive relation is σ=Eε(1-d)DIF c The dynamic damage constitutive model uses a linear damage degradation mode and uses the fracture energy G to control the damage evolution of the material. The fracture energy is related to the damage initiation equivalent stress and the damage initiation equivalent displacement strain rate. The equivalent displacement in the damage evolution stage remains unchanged, and the dynamic enhancement factor of the fracture energy is also DIF f The strength can be expressed as formula (1), the elastic modulus can be expressed as formula (2), and the equation of the random dynamic damage constitutive model can be expressed as formula (3).

[0014]

[0015] σ=E×ε×(1-d)×DIF c 3

[0016] The dynamic damage constitutive model also needs to select appropriate damage criteria and damage evolution rules. The selection of failure criteria is related to the specific material properties. In the stage of material damage evolution, strain localization problems will occur, which may cause the impact resistance of the composite material obtained by analysis to decrease with the refinement of the mesh. Introducing the unit characteristic length, selecting the linear damage degradation mode, and using the fracture energy to control the damage evolution of the material, the mesh dependence of the finite element analysis is reduced. Assume that the fracture energy size, the damage initiation equivalent stress and the damage initiation equivalent displacement strain rate are related, and the equivalent displacement in the damage evolution stage remains unchanged. At this time, the fracture energy can be expressed as formula (4), the dynamic damage initiation strain can be expressed as formula (5), the equivalent strain at material failure can be expressed as formula (6), and the dynamic damage factor can be expressed as formula (7).

[0017]

[0018] ε 0d =ε 0 ·(DIF f / DIF c )5

[0019] ε fd =ε f +ε 0 ·(DIF f / DIF c -1) 6

[0020]

[0021] Furthermore, in step S2, the dynamic damage constitutive model is used in the finite element software through secondary development. When the residual velocity obtained by the finite element simulation of the projectile impacting the composite plate is close to the experimental result, the selected constitutive parameter baseline value is reasonable, and the constitutive parameter at this time is used as the baseline value of the random dynamic damage constitutive model.

[0022] Furthermore, in step S3, the random dynamic damage constitutive model is established based on the energy probability model, which converts the uncertainty of the anti-elastic performance into the uncertainty of the constitutive parameters, greatly reducing the cost of obtaining the uncertainty parameters of the material constitutive model; the energy probability model uses a unified parameter to associate the strain energy and the fracture energy, so that the strength, elastic modulus, and fracture energy satisfy a linear relationship. When the absorbed energy becomes k times the original, the elastic strain energy changes to kE e, the fracture energy changes to kG. At this time, the strength is exactly kf, and the elastic modulus is exactly kE. The uncertainty of the mechanical properties of the micro-components of the composite material, the uncertainty of the micro-structure, the uncertainty of random defects in the manufacturing process, etc. will all affect the anti-ballistic performance of the composite material. In numerical simulation, heterogeneity can be used to characterize the discrete type of material properties. It is assumed that the equivalent uncertainty of the mechanical properties satisfies the half-normal distribution function, and a unified probability parameter is used to describe the uncertainty of strength, modulus, and fracture energy. The random number x satisfies the standard half-normal distribution with a standard deviation of 1. The mechanical properties of any integral point are X, σ X is the standard deviation of the distribution function of X. The benchmark values ​​of mechanical properties such as strength, modulus, and fracture energy measured by experiments are E(X), and the heterogeneous parameters are defined as pass It can be obtained that the mechanical properties parameters satisfy the average value μ=E(X), the standard deviation Finite element model of the folded normal distribution.

[0023] Further, in step S3, the random dynamic damage constitutive model is used in a commercial finite element software to simulate the impact of a projectile on a composite plate through secondary development. The incident velocity set in the numerical simulation is consistent with the experiment, and the heterogeneous parameters are adjusted. Until the residual velocity obtained by simulation is consistent with the experimental result, the inhomogeneous parameters of the constitutive model input are is the inhomogeneous parameter of the constitutive model of the specimen

[0024] Furthermore, in step S4, the inhomogeneous parameters of the stochastic dynamic damage constitutive model and the ballistic performance reliability parameter φ j Satisfaction between The relationship between the reliability parameter of the specimen and j The probability density function satisfies φ j ∶N(μ φ ,(σ φ ) 2 ) with a normal distribution model, mean μ = 1, standard deviation At this time, the heterogeneous parameters of each test specimen obtained in step S3 are used The reliability parameters of the specimen can be calculated The standard deviation of the probability density function of the anti-ballistic performance reliability parameter is then established.

[0025] V BL(i) ∶N(μ BL ,(σ BL ) 2 ) 8

[0026]

[0027] φ j ∶N(μ φ ,(σ φ ) 2 ) 10

[0028] Further, in step S5, the anti-ballistic performance reliability parameter φ is determined according to the anti-ballistic design reliability requirement. x and the constitutive model heterogeneity parameters The reliability of the ballistic design is equal to the reliability parameter φ in (φ x ,∞), satisfies When the reliability requirement of ballistic design is given as F(φ x ), the anti-ballistic performance reliability parameter φ can be obtained x , and then according to The heterogeneous parameters of the constitutive model can be obtained

[0029] Further, in step S6, the random dynamic damage constitutive model is used in the commercial finite element software through secondary development to simulate the projectile impact on the composite plate. The baseline value of the constitutive model parameter is set to the constitutive parameter verified in step S2, and the inhomogeneous parameter is set to the value calculated in step S5. The impact velocity of the projectile in the numerical simulation is set according to the anti-ballistic index. The thickness of the finite element model is adjusted according to the simulation results and the simulation is iterated until the thickness reaches the critical value at which the projectile can and cannot penetrate the composite material plate. This thickness is the design thickness that meets the anti-ballistic requirements.

[0030] The beneficial effects of the present invention are as follows: the present invention provides a method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model, which can not only reduce the time and cost of optimizing the anti-ballistic performance of composite materials, but also consider the reliability of anti-ballistic performance when optimizing the anti-ballistic performance of composite materials. Specifically, the method for optimizing the anti-ballistic performance of composite materials of the present invention establishes a random dynamic damage constitutive model of the composite material, and uses the constitutive model to optimize the anti-ballistic performance of the composite material through secondary development in finite element software. The method can effectively reduce the dependence of the design process on experience, reduce the number and cost of penetration tests, and optimize the design of a fiber-reinforced composite material plate that meets the anti-ballistic index and reliability requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a flow chart of a method for optimizing the anti-ballistic performance of a composite material based on a random constitutive model described in an embodiment of the present invention;

[0032] Figure 2This is a comparison and verification diagram of ballistic impact numerical simulation results and test results using a dynamic damage constitutive model of composite materials in an embodiment of the present invention;

[0033] Figure 3 Schematic diagram of the relationship between the uncertain parameters obtained in the embodiment of the present invention and the strength, elastic modulus and fracture energy;

[0034] Figure 4 is the probability density function of the uncertain parameters of the material constitutive model obtained in the embodiment of the present invention;

[0035] Figure 5 The reliability requirements of the anti-ballistic design and the reliability parameters of the anti-ballistic performance obtained in the embodiment of the present invention are relationship diagram. DETAILED DESCRIPTION

[0036] Specific embodiment 1: The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present invention. It should be noted that: in the present invention, if there is no special description, all the embodiments and preferred implementation methods mentioned herein can be combined with each other to form a new technical solution. In the present invention, if there is no special description, all the technical features and preferred features mentioned herein can be combined with each other to form a new technical solution. The "scope" disclosed in the present invention is in the form of lower limit and upper limit, which can be one or more lower limits, and one or more upper limits, respectively. Unless otherwise specified, the professional and scientific terms used in this article have the same meaning as those familiar to those skilled in the art. In addition, any method or material similar or equal to the recorded content can also be applied to the present invention.

[0037] As the specification of the present invention Figure 1 As shown, a method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model of the present invention comprises the following steps:

[0038] Step S1: prepare composite material specimens for ballistic impact tests and record the incident velocity V of the specimens. i - Remaining speed V r ;

[0039] Step S2, establishing a dynamic damage constitutive model of composite materials, carrying out ballistic impact numerical simulation by comparison test, and verifying the rationality of the reference values ​​of constitutive model parameters by comparing the test results;

[0040] Step S3: Establish a random dynamic damage constitutive model and calibrate the heterogeneous parameters of each test specimen through numerical simulation.

[0041] Step S4, establishing a probability density function of the anti-ballistic performance reliability parameter φ;

[0042] Step S5: Determine the reliability parameter φ of the anti-ballistic performance according to the reliability requirements of the anti-ballistic design x and the constitutive model heterogeneity parameters

[0043] Step S6: Carry out numerical simulation according to the requirements of the anti-ballistic index, and optimize the thickness of the composite material plate. The anti-ballistic performance optimization design method of the composite material based on the random constitutive model of the present invention is described in detail with reference to examples.

[0044] Specifically, the composite material in this embodiment adopts an aramid fiber vinyl ester resin-based composite material, the ballistic design reliability requirement is 60%, and the ballistic index requirement is to be able to prevent a GCr15 high-carbon chromium bearing steel ball with a diameter of 10.3 mm from impacting at a speed of 240 m / s; the specific optimization design method steps are as follows:

[0045] Step S1: Prepare composite material specimens for ballistic impact tests and record the incident velocity V of the specimens. i - Remaining speed V r ; The projectile used in the test is a GCr15 high carbon chromium bearing steel ball with a diameter of 10.3mm and a mass of 4.5g; the target plate is made of aramid fiber vinyl ester resin-based composite material, with a target plate size of 300mm*200mm and a thickness of 8mm. The gun used in the experiment is a 54-type 12.7mm ballistic gun, and the speed is monitored using an infrared light curtain speed measurement system. The four groups of incident speed-residual speed data obtained through the experiment in this embodiment are shown in Table 1 below:

[0046] Table 1 Ballistic impact test results

[0047] serial number Incident speed (m / s) Residual speed (m / s) K1 616.3 479.5 K2 797.4 669.0 K3 973.4 839.9 K4 985.5 849.6

[0048] Step S2: Establish a dynamic damage constitutive model for composite materials, conduct numerical simulation of ballistic impact in comparison with the test, and determine the rationality of the baseline values ​​of the constitutive model parameters by comparing the test results. A 300mm×200mm×8mm composite target plate finite element model and a 10.3mm diameter steel ball finite element model were established in comparison with the ballistic impact test. The dynamic damage constitutive model considers the following four failure modes: Equation (11) is the tensile shear failure in the in-plane main directions 1 and 2; Equation (12) is the compressive failure in the in-plane main directions 1 and 2; Equation (13) is the compressive failure in the thickness direction; Equation (14) is the compressive shear failure in the in-plane direction;

[0049]

[0050] The parameters selected for the dynamic damage constitutive model are shown in Table 2. The dynamic damage constitutive model is used in commercial finite element software through secondary development. When the residual velocity obtained by finite element simulation of projectile impacting the composite plate is close to the experimental result, the reference value of the selected constitutive model parameters is reasonable. The numerical simulation control test sets four incident velocities of 616.3, 797.4, 973.4, and 985.5 m / s, which are listed in the appendix of the manual. Figure 2 The comparison and verification of the ballistic impact numerical simulation results and test results of the composite material dynamic damage constitutive model in the embodiment of the present invention is shown in the figure; Figure 2 It can be seen that the numerical simulation results and the experimental results fit well, so the constitutive model parameters selected for numerical simulation are reasonable and can be used as the benchmark values ​​of constitutive parameters;

[0051] Table 2 Finite element model parameters

[0052] parameter unit size parameter unit size E1 MPa 2.10E+04 f2c MPa 200 E2 MPa 2.10E+04 f3t MPa 20 E3 MPa 4.60E++03 f12 MPa 77 v12 / 0.34 f13 MPa 100 v13 / 0.14 f23 MPa 100 v23 / 0.14 G1 N / mm 9 G12 MPa 1.30E+03 G2 N / mm 9 G13 MPa 1.30E+03 G3 N / mm 9 G23 MPa 1.30E+03 G4 N / mm 9 f1t MPa 800 G5 N / mm 9 f1c MPa 200 G6 N / mm 1 f2t MPa 800

[0053] Step S3: Establish a random dynamic damage constitutive model and calibrate the heterogeneous parameters of each test specimen through numerical simulation The random dynamic damage constitutive model is established based on the energy probability model. The energy probability model converts the uncertainty of anti-ballistic performance into the uncertainty of constitutive parameters, and obtains mechanical performance parameters that satisfy the half-normal distribution in the finite element model. Figure 3 Schematic diagram of the conversion between the uncertainty of anti-ballistic performance and the uncertainty of constitutive parameters in the embodiment of the present invention; the random dynamic damage constitutive model is used in the commercial finite element software through secondary development to simulate the impact of projectiles on composite plates. The numerical simulation also sets four incident velocities of 616.3, 797.4, 973.4, and 985.5 m / s to adjust the heterogeneous parameters Until the residual velocity obtained by simulation is consistent with the experimental result, the inhomogeneous parameters input is the inhomogeneity parameter of the test specimen Table 3 shows the inhomogeneous parameters of each test specimen obtained by calibration.

[0054] Table 3. Inhomogeneous parameters of each test specimen obtained by calibration

[0055]

[0056] Step S4: Establish the probability density function of the anti-ballistic performance reliability parameter φ; The inhomogeneous parameter φ of the random dynamic damage constitutive model is j Converted into anti-ballistic performance reliability parameter φ j Table 4 below shows the reliability parameters of each test specimen after conversion;

[0057] Table 4 Reliability parameters of each test specimen

[0058] serial number Heterogeneous parameters Reliability parameters K1 0.38 1.175 K2 .0.02 0.990 K3 .0.14 0.927 K4 .0.07 0.964

[0059] Specimen reliability parameter φ j The probability density function satisfies the normal distribution model of formula 3, and the average value μ φ =1, standard deviation Substituting the obtained reliability parameters into the standard deviation σ φ =0.103066. So the probability density function of the reliability parameter satisfies φ j :N(1,(0.103066) 2 ), please refer to the instruction manual Figure 4 Probability density function diagram of uncertain parameters of the material constitutive model obtained in an embodiment of the present invention.

[0060] Step S5: Determine the reliability parameter φ of the ballistic performance according to the reliability requirements of the ballistic design x and the constitutive model heterogeneity parameters The reliability of the ballistic design is equal to the reliability parameter φ in (φ x ,∞), satisfies When the reliability requirement of ballistic design is given as F(φ x ), the anti-ballistic performance reliability parameter φ can be obtained x , and then according to The inhomogeneous parameter φ of the constitutive model can be obtained x The reliability requirement of this embodiment is 60%, and the reliability parameter of the anti-ballistic performance at this time can be obtained by calculation: x =1.026111, heterogeneous parameters of constitutive model Please refer to the instruction manual Figure 5 A relationship diagram between the reliability requirements and the uncertain parameter values ​​of the material constitutive model obtained in an embodiment of the present invention.

[0061] Step S6: Carry out numerical simulation according to the requirements of the anti-ballistic index and optimize the thickness of the composite material plate; simulate the impact of the projectile on the composite material plate by using the established random dynamic damage constitutive model through secondary development in the commercial finite element software, and set the baseline value of the constitutive model parameter to the constitutive parameter verified in step S2, and the heterogeneous parameter to the value calculated in step S5. The reference values ​​of the constitutive model parameters in this embodiment are the parameter values ​​in Table 2, and the heterogeneous parameters of the constitutive model are set to the values ​​calculated in step S5. The projectile impact velocity of the numerical simulation is set according to the anti-ballistic index. The thickness of the finite element model is adjusted according to the simulation results and the simulation is repeated until the thickness reaches the critical value at which the projectile can penetrate the composite material plate and cannot penetrate the composite material plate. This thickness is the design thickness that meets the anti-ballistic requirements. The projectile impact velocity V required by the anti-ballistic index of this embodiment i =240m / s, and the plate thickness optimized by numerical simulation is 11mm.

[0062] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model, characterized in that: The steps include: S1. Prepare composite material specimens for ballistic impact tests and record the incident velocity V of the specimens. i - Remaining speed V r ; S2. Establish a dynamic damage constitutive model for composite materials, conduct numerical simulation of ballistic impact with control tests, and verify the rationality of the baseline values ​​of constitutive model parameters by comparing test results; S3. Establish a random dynamic damage constitutive model and calibrate the heterogeneous parameters of each test specimen through numerical simulation S4, establishing the probability density function of the anti-ballistic performance reliability parameter φ; S5. Determine the reliability parameter φ of the ballistic performance according to the reliability requirements of the ballistic design x and the constitutive model heterogeneity parameters S6. Carry out numerical simulation according to the requirements of anti-ballistic index and optimize the thickness of composite material plate; In step S2, the strength of the dynamic damage constitutive model is f, the Young's modulus is E, and the dynamic enhancement factor is used to consider the strain rate effect. The dynamic enhancement factor of elastic modulus is DIF c , the intensity dynamic enhancement factor is DIF f , the constitutive relation is σ=Eε(1-d)DIF c The dynamic damage constitutive model uses a linear damage degradation mode and uses the fracture energy G to control the damage evolution of the material. The fracture energy is related to the damage initiation equivalent stress and the damage initiation equivalent displacement strain rate. The equivalent displacement in the damage evolution stage remains unchanged, and the dynamic enhancement factor of the fracture energy is also DIF f ; In step S3, the random dynamic damage constitutive model is established based on the energy probability model. The energy probability model converts the uncertainty of the anti-elastic performance into the uncertainty of the constitutive parameters, which greatly reduces the cost of obtaining the uncertainty parameters of the material constitutive model. The energy probability model uses a unified parameter to associate the strain energy and the fracture energy, so that the strength, elastic modulus, and fracture energy satisfy a linear relationship. When the absorbed energy becomes k times the original, the elastic strain energy changes to kE e , the fracture energy changes to kG, at this time, the strength is exactly kf, and the elastic modulus is exactly kE; In step S5, the anti-ballistic performance reliability parameter φ is determined according to the anti-ballistic design reliability requirement. x and the constitutive model heterogeneity parameters The reliability of the ballistic design is equal to the reliability parameter φ in (φ x ,∞), satisfies When the reliability requirement of ballistic design is given as F(φ x ), the anti-ballistic performance reliability parameter φ can be obtained x , and then according to The heterogeneous parameters of the constitutive model can be obtained 2. The method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model according to claim 1, characterized in that: In step S2, the dynamic damage constitutive model is used in the finite element software through secondary development. When the residual velocity obtained by the finite element simulation of the projectile impacting the composite plate is close to the experimental result, the selected constitutive parameter baseline value is reasonable, and the constitutive parameter at this time is used as the baseline value of the random dynamic damage constitutive model.

3. The method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model according to claim 2, characterized in that: In step S3, the random dynamic damage constitutive model is used in a commercial finite element software to simulate the impact of a projectile on a composite plate through secondary development. The incident velocity set in the numerical simulation is consistent with the experiment, and the heterogeneous parameters are adjusted. Until the residual velocity obtained by simulation is consistent with the experimental result, the inhomogeneous parameters of the constitutive model input are is the inhomogeneous parameter of the constitutive model of the specimen 4. The method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model according to claim 3, characterized in that: In step S4, the inhomogeneous parameters of the stochastic dynamic damage constitutive model are and the ballistic performance reliability parameter φ j Satisfaction between The relationship between the reliability parameter φ of the specimen j The probability density function satisfies φ j :N*(μ φ ,(σ φ ) 2 ) with a normal distribution model, mean μ = 1, standard deviation At this time, the heterogeneous parameters of each test specimen obtained in step S3 are used The reliability parameters of the specimen can be calculated The standard deviation of the probability density function of the anti-ballistic performance reliability parameter is then established.

5. The method for optimizing the anti-ballistic performance of composite materials based on a random constitutive model according to claim 4, characterized in that: In step S6, the random dynamic damage constitutive model is used in the commercial finite element software through secondary development to simulate the projectile impact on the composite plate. The baseline value of the constitutive model parameter is set to the constitutive parameter verified in step S2, and the heterogeneous parameter is set to the value calculated in step S5. The impact velocity of the projectile in the numerical simulation is set according to the anti-ballistic index. The thickness of the finite element model is adjusted according to the simulation results and the simulation is iterated until the thickness reaches the critical value at which the projectile can and cannot penetrate the composite material plate. This thickness is the design thickness that meets the anti-ballistic requirements.

Images