A method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests

Abstract

The present invention provides a method for evaluating the impact safety of explosive charges based on equivalent model tests, including: S10, obtaining the dynamic mechanical parameters of the explosive charge and selecting a constitutive model, then determining its undetermined parameters, obtaining the curve of the shock wave pressure varying with the measurement position, and determining the parameters of the three-term ignition growth model in combination with finite element software; S20, obtaining the remaining velocity of the bullet after penetrating the shell and the deformation and damage morphology of the bullet head; S30, conducting equivalent model tests according to S20 to obtain the velocity intervals corresponding to different safety response levels; establishing a geometric model of the equivalent model test, substituting the model determined in S10 into the geometric model of the equivalent model test to obtain the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge at different impact velocities; combining the results of the equivalent model test and numerical simulation to obtain the intervals of the maximum equivalent stress, maximum shear stress, and reactivity corresponding to different response levels of the explosive charge.

Description

Technical Field

[0001] The present invention belongs to the technical field of explosive charge safety, and particularly relates to a method for evaluating the bullet impact safety of explosive charges based on equivalent model tests. Background Art

[0002] In recent years, with the increasingly complex operating environment of weapon systems and the large-scale application of high-value weapon ammunition on the battlefield, the requirements for the survivability of weapon ammunition have become higher and higher. On the modern battlefield and during wartime transportation, bullet impact is one of the common threats to warheads. In the United States' MIL-STD2105D and NATO's STANAG 4439-2010 low-vulnerability ammunition hazard assessment test standards, bullet impact tests are essential assessment items.

[0003] Currently, the main methods for evaluating the bullet impact safety of explosive charges include live ammunition tests, model tests, and numerical simulation methods. Live ammunition tests usually use standard 12.7mm armor-piercing incendiary bullets to impact scaled-down sample projectiles or full-scale warheads at a speed of (850±20) m / s. This live ammunition test method is simple and intuitive, but it has high costs, a long cycle, and high safety risks. The numerical simulation method is one of the important means to reduce test costs. At the same time, it can obtain the variation laws of process parameters such as local deformation, damage, and reactivity of materials that cannot be observed in tests. However, these results are closely related to the setting of model parameters, boundary conditions, and contact conditions. And because it is difficult to accurately obtain the basic performance parameters of explosives under dynamic load, the numerical simulation model needs to be calibrated in combination with test results. Currently, it is difficult to calculate the actual reaction level of the charge using the numerical simulation method. Model tests are equivalent simulation test methods designed for laboratory charge amounts to obtain the reaction of explosive charges under different loading conditions and, based on this, evaluate the bullet impact stability of explosive charges. The test has high safety and low research costs and is applicable to all stages of project demonstration, engineering development, and finalization. The deficiencies and defects of existing research technologies are manifested in the following two aspects: (1) Existing methods cannot obtain the relationship between the response level of explosive charges under shock compression shear and internal response parameters, and cannot accurately evaluate their safety performance; (2) The research method of full-scale live ammunition tests has high research costs, a long cycle, and high safety risks. Summary of the Invention

[0004] Aiming at the deficiencies of the existing technology, the purpose of the present invention is to provide a method for evaluating the bullet impact safety performance of explosive charges to solve the problems existing in the existing technology.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions:

[0006] A method for evaluating the impact safety of explosive charges based on equivalent model tests, comprising:

[0007] S10. Obtain the dynamic mechanical parameters of the explosive charge, select a constitutive model, and then determine its undetermined parameters; obtain the curve of the shock wave pressure varying with the measurement position, and combine with finite element software to determine the parameters of the three-term ignition growth model;

[0008] S20. Obtain the residual velocity of the bullet after penetrating the shell and the head deformation and damage morphology;

[0009] S30. Select the impact velocity range of the explosive charge under compression and shear loading according to the residual velocity determined in S20, design the geometric shape of the impact indenter according to the head deformation and damage morphology, conduct equivalent model tests, and obtain the velocity intervals corresponding to different safety response levels; establish a numerical simulation model of the equivalent model test, and input the constitutive model of the explosive and the parameters of the three-term ignition growth model determined in S10 to obtain the maximum equivalent stress, maximum shear stress and reactivity of the explosive charge at different impact velocities; combine the results of the equivalent model test and numerical simulation to obtain the intervals of the maximum equivalent stress, maximum shear stress and reactivity corresponding to different response levels of the explosive charge;

[0010] S40. Conduct a numerical simulation analysis of the bullet impact on the full-scale warhead, and obtain the maximum equivalent stress, maximum shear stress and reactivity of the explosive charge under the bullet impact of the full-scale warhead;

[0011] S50. Based on the correlation between the response level of the explosive charge and the maximum equivalent stress, maximum shear stress and reactivity obtained from the equivalent model test and numerical simulation analysis in step S30, and combining the maximum equivalent stress, maximum shear stress and reactivity of the explosive charge obtained from the numerical simulation analysis of the bullet impact on the full-scale warhead in step S40, estimate the safety response level of the bullet impact on the full-scale warhead.

[0012] Preferably, in S10, a passive confining pressure device based on a Hopkinson bar loading system is used to conduct a triaxial compression test on the explosive material,

[0013] wherein, the triaxial compression test of the explosive material using the passive confining pressure device of the Hopkinson bar loading system is to use a bullet driven by high-pressure gas to impact the incident bar at a certain speed, and compress and load the explosive sample through the generated incident pulse, so that the explosive generates axial deformation while being laterally constrained by the confining tube. During the test, strain signals during the loading process are measured by strain gauges pasted on the incident bar, transmission bar and confining tube,

[0014] and the stress σ, strain ε and strain rate of the explosive are calculated respectively

[0015]

[0016]

[0017]

[0018] Among them, ε t is the transmitted strain, ε r is the reflected strain, E is the elastic modulus of the rod, A b and A s are the cross-sectional areas of the rod and the specimen respectively, C is the elastic wave speed in the rod, l s is the specimen thickness;

[0019] Thus, the dynamic compression stress-strain curve of the explosive material is obtained, its performance parameters such as elastic modulus and yield stress are determined, and after selecting the constitutive model, its undetermined parameters are determined.

[0020] Preferably, in the S10, a tensile experiment of the explosive is carried out to obtain the curve of the shock wave pressure changing with the measurement position, and the parameters of the three-term ignition growth model are determined by combining with finite element software. The three-term ignition growth model is:

[0021]

[0022] In the formula, F is the explosive reactivity, p is the pressure, t is the time, I, G1, G2, a, b, c, d, e, g, x, y, z are constants, and ρ and ρ0 are the current density and initial density of the explosive respectively.

[0023] Preferably, in the S20, a bullet is launched by a ballistic gun to impact a metal target plate, and the residual velocity and the head damage morphology after the bullet penetrates the target plate are obtained. Among them, the material and thickness of the metal target plate are the same as those of the warhead shell. A velocity measurement target is arranged behind the target plate to obtain the residual velocity of the projectile after penetrating the metal target plate, and the deformation and damage characteristics after the bullet penetrates the target plate are determined.

[0024] Preferably, in the S40, a bullet impacts a full-scale warhead. According to the geometric structure of the actual warhead and the explosive constitutive model and the parameters of the three-term ignition growth model determined in S10, a numerical simulation analysis of the bullet impacting the full-scale warhead is carried out by using finite element software to obtain the maximum equivalent stress, the maximum shear stress and the reactivity of the explosive charge in the full-scale warhead under the impact of the bullet.

[0025] Preferably, in order to obtain the velocity intervals corresponding to different safety response levels, the device for the S equivalent model test includes: including a sleeve and a punching and shearing press head. The punching and shearing press head is arranged in the sleeve. It is characterized in that

[0026] It also includes a fixing ring and a baffle. The fixing ring is sleeved inside the sleeve. A first through hole and a second through hole are respectively arranged at both ends of the fixing ring. An explosive charge column is filled in the second through hole. The baffle is fixedly sleeved inside the sleeve and connected to one side of the fixing ring where the second through hole is arranged to block the explosive charge column. One end of the punching and shearing punch can penetrate into the first through hole and contact the explosive charge column.

[0027] Preferably, the device for the S equivalent model test further includes a washer. The washer is arranged inside the fixing ring on the side close to the first through hole. A third through hole is arranged in the washer. The third through hole matches the first through hole. One end of the punching and shearing punch can penetrate into the third through hole of the washer.

[0028] Preferably, a fixing step is arranged inside the sleeve. The fixing ring is arranged on the fixing step. The fixing step is used to prevent the fixing ring from moving towards the punching and shearing punch side inside the sleeve.

[0029] Preferably, the device for the S equivalent model test further includes an upper striking column and a lower striking column. Both the upper striking column and the lower striking column are sleeved on the sleeve. One end of the upper striking column is connected to the punching and shearing punch, and the other end extends out of the sleeve; one end of the lower striking column is connected to the baffle, and the other end extends out of the sleeve.

[0030] Preferably, a pressure relief hole is arranged on the side wall of the sleeve. The pressure relief hole is located between the punching and shearing punch and the fixing ring. A convex platform is arranged on the punching and shearing punch. The convex platform can penetrate into the first through hole. The pressure relief hole communicates with a groove on one side of the convex platform.

[0031] Compared with the prior art, the present invention has the following technical effects:

[0032] (Ⅰ) For a method for evaluating the bullet impact safety of an explosive charge based on an equivalent model test of the present invention, on the one hand, a model test for the impact compression and shear loading of a local charge when the warhead is impacted by a bullet is designed. Combining the internal stress distribution characteristics of the charge obtained by numerical simulation analysis and the explosive charge reaction level obtained by the model test, the safety reaction level of a full-scale warhead under the action of bullet impact can be predicted, and its safety performance can be judged; on the other hand, all tests can be carried out under laboratory conditions. Compared with the full-scale live ammunition test research method, it has the advantages of low research cost, short cycle, high safety, etc.

[0033] (Ⅱ) The equivalent test device adopted by a method for evaluating the bullet impact safety of an explosive charge based on an equivalent model test of the present invention can be closer to the compression and shear load characteristics of the explosive charge under the constraint condition after the local perforation of the shell under the action of a real bullet impact. And after the explosive charge column is impacted and broken, the broken charge column will not be ignited due to secondary impact, which will cause confusion to the test results. The device of the present invention effectively improves the accuracy of the equivalent test results and the accuracy of the safety level evaluation. Description of the Drawings

[0034] Figure 1 is the flow chart of the present invention;

[0035] Figure 2 is the flow chart of the safety evaluation method of the present invention;

[0036] Figure 3 is the schematic diagram of the impact compression shear model test device for explosive charge of the present invention;

[0037] Figure 4 is the schematic diagram of the punching, shearing and pressing head structure of the impact compression shear model test device for explosive charge of the present invention;

[0038] Figure 5 is the schematic diagram of the fixed ring structure of the impact compression shear model test device for explosive charge of the present invention;

[0039] Figure 6 is the stress-strain curve of explosive B in this embodiment.

[0040] The meanings of each label in the figure are as follows:

[0041] 1. Upper impact column, 2. Punching, shearing and pressing head, 2-1. Boss, 3. Fixed ring, 3-1. First through hole, 3-2. Second through hole, 4. Washer, 5. Explosive charge column, 6. Baffle, 7. Lower impact column, 8. Sleeve, 9. Fixed step, 10. Pressure relief hole.

[0042] The following further elaborates on the specific content of the present invention in conjunction with embodiments. Specific Embodiments

[0043] The following provides specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations made on the basis of the technical solutions of this application fall within the protection scope of the present invention.

[0044] The directional terms mentioned in this article, such as "lateral", "radial", "axial", "horizontal" and "vertical", are consistent with the specific directions on the paper surface of the specification drawings or the corresponding directions in the space shown in the drawings.

[0045] Embodiment 1:

[0046] This embodiment is a certain typical penetration and explosion type warhead filled with explosive B impacted by a bullet.

[0047] Step 1: Dynamic mechanical property test and tensile experiment of explosive charge

[0048] The dynamic mechanical properties of explosive B under constrained conditions are tested using a passive confining pressure device based on a split Hopkinson pressure bar system. The dynamic compressive stress-strain curve of explosive B can be obtained from the measured strain signal and formulas (1) to (3), as Figure 6As shown, its yield strength is about 200 MPa and its shear modulus is about 3.54 GPa. In this embodiment, the ELASTIC_PLASTIC_HYDRO constitutive model is selected. This constitutive model can describe the stress-strain relationship of explosive materials through simple parameters such as material density, shear modulus, and yield strength, and is widely used in numerical simulation analysis of materials such as explosives and propellants. The specific parameters are shown in Table 1.

[0049] Further conduct the pull test of the explosive to obtain the curve of the shock wave pressure changing with the measurement position, and determine the parameters of the three-term ignition growth model in combination with the finite element software. The three-term ignition growth model includes an ignition term, a combustion term, and a reaction completion term, and its formula is:

[0050]

[0051] In the formula, F is the explosive reactivity, p is the pressure, t is the time, I, G1, G2, a, b, c, d, e, g, x, y, z are constants, ρ and ρ0 are the current density and initial density of the explosive respectively, and the model parameters are shown in Table 2.

[0052] Table 1 Constitutive model parameters of Composition B explosive

[0053]

[0054] Among them, R0 is the material density, G is the shear modulus, SIGY is the yield strength, EH is the plastic hardening modulus, and PC is the pressure cut-off value.

[0055] Table 2 Parameters of the three-term ignition growth model of Composition B explosive

[0056]

[0057]

[0058] In the formula, CVP and CVR are the heat capacities of the reaction products and unreacted explosives; ENQ is the heat of reaction; TMP0 is the initial temperature; FMXIG, FMXGR, and FMNGR are the maximum reactivities of the ignition term, combustion term, and reaction completion term respectively; the rest are undetermined parameters.

[0059] Step 2: Determine the remaining velocity and head shape of the bullet after penetrating the shell

[0060] Use a ballistic gun to fire a 12.7 mm standard armor-piercing incendiary bullet to impact a 20 mm thick 35CrMnSi target plate at a speed of (850 ± 20) m / s. The remaining velocity of the bullet after penetrating the target is calculated to be 309 m / s through the velocity measuring target behind the target plate, and the head of the recovered bullet is severely damaged.

[0061] Step 3: Determine the equivalent model test method and numerical simulation analysis

[0062] Determine the shape of the punching and shearing punch according to the test results of Step 2. In this embodiment, since the warhead is severely damaged, the punching and shearing punch is simplified to a cylindrical shape. Based on the remaining velocity of the projectile determined in Step 2, expand the impact velocity range of the test. In this embodiment, conduct model tests within the impact velocity range of 250 m / s to 420 m / s, and determine the velocity intervals corresponding to different reaction levels of the explosive charge through the test results. In this embodiment, within the velocity interval of 250 m / s to 270 m / s, the explosive charge does not burn or detonate; within the velocity interval of 280 m / s to 320 m / s, the explosive charge undergoes a combustion reaction; within the velocity interval of 330 m / s to 420 m / s, the explosive charge undergoes a deflagration reaction.

[0063] Furthermore, use LS-DYNA finite element software to establish the geometric model of the equivalent model test, and input the explosive constitutive model and the parameters of the three-term ignition growth model determined in S10, conduct numerical simulation analysis of the equivalent model test at different velocities, and determine the numerical ranges of the maximum equivalent stress, maximum shear stress, and reaction degree of the charge within different velocity intervals. In this embodiment, within the velocity interval of 250 m / s to 270 m / s, the maximum equivalent stress inside the charge is 143 MPa to 177 MPa, the maximum shear stress is 53 MPa to 71 MPa, and the reaction degree is 0 to 0.005; within the velocity interval of 280 m / s to 320 m / s, the maximum equivalent stress inside the charge is 185 MPa to 224 MPa, the maximum shear stress is 75 MPa to 91 MPa, and the reaction degree is 0.003 to 0.01; within the velocity interval of 330 m / s to 420 m / s, the maximum equivalent stress inside the charge is 252 MPa to 385 MPa, the maximum shear stress is 93 MPa to 132 MPa, and the reaction degree is 0.02 to 0.25.

[0064] Combining the test results and the numerical simulation analysis results, the correlation between the reaction level of the explosive charge and the internal response parameters can be obtained.

[0065] Step 4: Numerical simulation analysis of bullet impact on the full-scale warhead

[0066] Use LS-DYNA finite element software to establish the numerical geometric model of bullet impact on the full-scale warhead, and input the explosive constitutive model and the three-term ignition growth model determined in Step 1, conduct numerical simulation analysis of the bullet impacting the full-scale warhead at a velocity of (850 ± 20) m / s, and calculate that the maximum equivalent stress is 220 MPa, the maximum shear stress is 83 MPa, and the reaction degree is 0.006.

[0067] Step 5: Estimate the safety response level of bullet impact on the full-scale warhead

[0068] Based on the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge under the impact of the full-scale warhead bullet obtained in Step 4, and comparing with the maximum equivalent stress, maximum shear stress, and reactivity intervals corresponding to different reaction levels obtained in Step 3, it is estimated that the safety response level of the full-scale warhead bullet impact is combustion.

[0069] As a preferred solution of this embodiment, the device for the S30 equivalent model test includes: a sleeve 8 and a punching and shearing press head 2, the punching and shearing press head 2 is arranged inside the sleeve 8, and it is characterized in that

[0070] It further includes a fixing ring 3 and a baffle 6. The fixing ring 3 is sleeved inside the sleeve 8. The two ends of the fixing ring 3 are respectively provided with a first through hole 301 and a second through hole 302. An explosive charge column 5 is filled in the second through hole 302. The baffle 6 is fixedly sleeved inside the sleeve 8 and is connected to one side of the fixing ring 3 where the second through hole 302 is provided to block the explosive charge column 5. One end of the punching and shearing press head 2 can penetrate into the first through hole 301 and contact the explosive charge column 5.

[0071] Among them, in the device of this embodiment, by arranging a fixing ring inside the sleeve and placing the explosive charge column in the first through hole of the fixing ring, the explosive charge column can be fixed by the baffle. When the punching and shearing press head impacts the explosive charge column through the first through hole, there is no axial displacement of the explosive around the impact point during the impact compression and shearing process, which is closer to the compression and shearing load characteristics of the explosive charge under the constraint condition after the local perforation of the shell under the action of a real bullet impact. Moreover, after the explosive charge column is impacted and broken, the broken charge column will not be ignited due to secondary impact, which will not cause confusion to the test results. The device of the present invention effectively improves the accuracy of the equivalent test results and further improves the accuracy of the safety level assessment.

[0072] As a preferred solution of this embodiment, the device for the S30 equivalent model test further includes a washer 4. The washer 4 is arranged inside the fixing ring 3 on the side close to the first through hole 301. A third through hole is provided in the washer 4, and the third through hole matches the first through hole 301. One end of the punching and shearing press head 2 can penetrate into the third through hole of the washer 4.

[0073] Among them, the washer 4 is used to prevent premature ignition caused by the extrusion of the edge of the explosive charge column and the metal contact surface of the fixing ring, which affects the accuracy of the test of the device in this embodiment. Its thickness is usually about 1 mm, and the material must be a non-metallic material. In this embodiment, the vertical length of the thickness of the washer 4 is 1 mm, and the material is polyethylene.

[0074] As a preferred solution of this embodiment, a fixing step 9 is arranged inside the sleeve 8, and the fixing ring 3 is arranged on the fixing step 9. The fixing step 9 is used to prevent the fixing ring 3 from moving towards the side of the punching and shearing press head 2 inside the sleeve 8.

[0075] Among them, the fixed step 9 is used to limit the upward movement of the fixed ring 3 caused by the reaction force during the deformation of the explosive charge during the impact process, which can ensure the constraint effect of the fixed ring 3 on the explosive charge during the entire loading process, avoid the axial displacement of the explosive around the boss of the punching and shearing punch 2 during the deformation process, be closer to the compression and shear load characteristics of the explosive charge under the constraint condition after the local perforation of the projectile under the action of a real bullet impact, and further improve the test efficiency of this embodiment.

[0076] As a preferred solution of this embodiment, the device for the S30 equivalent model test further includes an upper impact column 1 and a lower impact column 7. Both the upper impact column 1 and the lower impact column 7 are sleeved on the sleeve 8. One end of the upper impact column 1 is connected to the punching and shearing punch 2, and the other end extends out of the sleeve 8; one end of the lower impact column 7 is connected to the baffle 6, and the other end extends out of the sleeve 8. A pressure relief hole 10 is provided on the side wall of the sleeve 8, and the pressure relief hole 10 is located between the punching and shearing punch 2 and the fixed ring 3. A boss 2-1 is provided on the punching and shearing punch 2, and the boss 2-1 can extend into the first through hole 301, and the pressure relief hole 10 communicates with the groove on one side of the boss 2-1.

[0077] Among them, the fixed step 9 is used to limit the upward movement of the fixed ring 3 caused by the reaction force during the deformation of the explosive charge during the impact process, which can ensure the constraint effect of the fixed ring 3 on the explosive charge during the entire loading process, avoid the axial displacement of the explosive around the boss of the punching and shearing punch 2 during the deformation process, be closer to the compression and shear load characteristics of the explosive charge under the constraint condition after the local perforation of the projectile under the action of a real bullet impact, and further improve the test efficiency of this embodiment. The upper impact column 1 and the lower impact column 7 are made of T10A steel, and the upper impact column 1 and the lower impact column 7 are used to transmit loads. During the test, the bullet impact speed can be measured by a laser velocimeter, and the pressure relief hole on the sleeve can ensure that the upper impact column is not affected by the air compression resistance in the closed space during the movement. If the explosive charge reacts, the high-pressure gas products generated can also be discharged from the pressure relief hole, so that it is closer to the action process of the bullet impact in the ammunition safety assessment test, and further improves the accuracy of the test of the device in this embodiment. The boss structure can extend into the first through hole 301, which is beneficial to promoting the movement of the explosive charge. The pressure relief hole 10 communicates with the groove on one side of the boss 2-1, which is beneficial to the discharge of the high-pressure gas from the pressure relief hole. In this embodiment, the diameter of the pressure relief hole is 10 mm.

Claims

1. A method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests, characterized in that, Including: S10. Obtain the dynamic mechanical parameters of the explosive charge, select a constitutive model, and then determine its undetermined parameters; obtain the curve of the shock wave pressure varying with the measurement position, and determine the parameters of the three-term ignition growth model in combination with finite element software; among them, conduct a split Hopkinson pressure bar (SHPB) test on the explosive to obtain the curve of the shock wave pressure varying with the measurement position, and determine the parameters of the three-term ignition growth model in combination with finite element software. The three-term ignition growth model is: In the formula, F is the explosive reactivity, p is the pressure, t is the time, I, G1, G2, a, b, c, d, e, g, x, y, z are constants, and ρ and ρ0 are the current density and initial density of the explosive, respectively; S20. Obtain the residual velocity of the bullet after penetrating the shell and the head deformation and damage morphology; S30. Select the impact velocity range of the explosive charge compression and shear loading according to the residual velocity determined in S20, design the geometric shape of the impact indenter according to the head deformation and damage morphology, conduct an equivalent model test, and obtain the velocity intervals corresponding to different safety response levels; establish a numerical simulation model of the equivalent model test, and input the constitutive model of the explosive and the parameters of the three-term ignition growth model determined in S10 to obtain the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge at different impact velocities; combine the results of the equivalent model test and the numerical simulation to obtain the intervals of the maximum equivalent stress, maximum shear stress, and reactivity corresponding to different response levels of the explosive charge; S40. Conduct a numerical simulation analysis of the bullet impact on the full-scale warhead to obtain the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge under the bullet impact of the full-scale warhead; S50. Based on the correlation between the response level of the explosive charge and the maximum equivalent stress, maximum shear stress, and reactivity obtained from the equivalent model test and numerical simulation analysis in step S30, and combined with the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge obtained from the numerical simulation analysis of the bullet impact on the full-scale warhead in step S40, estimate the safety response level of the bullet impact on the full-scale warhead.

2. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 1, characterized in that, In S10, a passive confining pressure device based on a split Hopkinson pressure bar (SHPB) loading system is used to conduct a triaxial compression test on the explosive material. Among them, the passive confining pressure device of the split Hopkinson pressure bar (SHPB) loading system conducts a triaxial compression test on the explosive material by using a bullet driven by high-pressure gas to impact the incident bar at a certain speed, and compresses and loads the explosive specimen through the generated incident pulse, so that the explosive generates axial deformation while being laterally constrained by the confining tube. During the test, strain gauges are pasted on the incident bar, transmission bar, and confining tube to measure the strain signals during the loading process. The stress σ, strain ε, and strain rate of the explosive are calculated separately Among them, ε t is the transmitted strain, ε r is the reflected strain, E is the elastic modulus of the rod, A b and A s are the cross-sectional areas of the rod and the specimen respectively, C is the elastic wave velocity in the rod, l s is the specimen thickness; Thereby, obtain the dynamic compression stress-strain curve of the explosive material, determine its performance parameters such as elastic modulus and yield stress, select a constitutive model, and then determine its undetermined parameters.

3. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 1, characterized in that, In S20, a ballistic gun is used to fire a bullet to impact a metal target plate to obtain the residual velocity of the bullet after penetrating the target plate and the head damage morphology. Among them, the material and thickness of the metal target plate are the same as those of the warhead shell. A velocity measurement target is arranged behind the target plate to obtain the residual velocity of the projectile after penetrating the metal target plate, and determine the deformation and damage characteristics of the bullet after penetrating the target plate.

4. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 1, characterized in that, In S40, a bullet impacts a full-scale warhead. Based on the geometric structure of the actual warhead, the constitutive model of the explosive, and the parameters of the three-term ignition growth model determined in S10, a finite element software is used to conduct a numerical simulation analysis of the bullet impacting the full-scale warhead, and the maximum equivalent stress, maximum shear stress, and reactivity of the explosive charge in the full-scale warhead under the impact of the bullet are obtained.

5. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 1, characterized in that, To obtain the speed intervals corresponding to different safety response levels, the device for the S30 equivalent model test includes: a sleeve (8) and a punching shear and pressing head (2), and the punching shear and pressing head (2) is arranged inside the sleeve (8), and is characterized in that it further includes a fixing ring (3) and a baffle (6). The fixing ring (3) is sleeved inside the sleeve (8). A first through hole (301) and a second through hole (302) are respectively arranged at both ends of the fixing ring (3). An explosive charge column (5) is filled in the second through hole (302). The baffle (6) is fixedly sleeved inside the sleeve (8) and is connected to one side of the fixing ring (3) where the second through hole (302) is arranged to block the explosive charge column (5). One end of the punching shear and pressing head (2) can penetrate into the first through hole (301) and contact the explosive charge column (5).

6. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 5, characterized in that, The device for the S30 equivalent model test further includes a washer (4). The washer (4) is arranged on one side of the fixing ring (3) close to the first through hole (301). A third through hole is arranged in the washer (4), and the third through hole matches the first through hole (301). One end of the punching shear and pressing head (2) can penetrate into the third through hole of the washer (4).

7. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 6, characterized in that, A fixing step (9) is arranged inside the sleeve (8), and the fixing ring (3) is arranged on the fixing step (9). The fixing step (9) is used to prevent the fixing ring (3) from moving towards the punching shear and pressing head (2) side inside the sleeve (8).

8. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 7, characterized in that, The device for the S30 equivalent model test further includes an upper impact column (1) and a lower impact column (7). Both the upper impact column (1) and the lower impact column (7) are sleeved on the sleeve (8). One end of the upper impact column (1) is connected to the punching shear and pressing head (2), and the other end extends out of the sleeve (8); one end of the lower impact column (7) is connected to the baffle (6), and the other end extends out of the sleeve (8).

9. The method for evaluating the impact safety of explosive charges in bullets based on equivalent model tests according to claim 8, characterized in that, A pressure relief hole (10) is arranged on the side wall of the sleeve (8). The pressure relief hole (10) is located between the punching shear and pressing head (2) and the fixing ring (3). A boss (2-1) is arranged on the punching shear and pressing head (2). The boss (2-1) can penetrate into the first through hole (301), and the pressure relief hole (10) communicates with a groove on one side of the boss (2-1).

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