A visualization method for evaluating the damage capability of EFP post-target fragments

Abstract

The application discloses a kind of visual methods for evaluating EFP target rear fragment damage ability, on the basis of considering the speed, mass and scattering direction of target rear fragment, the number of fragment, mass, fragment distribution density, fragment energy distribution density and other characteristic parameters in different scattering angle interval are statistically divided in combination with fragment penetration theory, and the distribution of target rear fragment on verification target is obtained.The method given by the application can obtain a large number of target rear fragment aftereffect damage characteristic parameter information of verification target, directly reflect the damage of target rear fragment to verification target, and can distinguish the source of target rear fragment leading to the perforation of verification target, and can provide reference for evaluating the visual analysis of EFP target rear fragment damage ability.

Description

Technical Field

[0001] This invention relates to the field of back-to-target fragmentation damage, and more specifically to a visualization method for assessing the back-to-target fragmentation damage capability of explosively formed projectiles (EFP). Background Technology

[0002] The destructive power of an EFP warhead includes its penetration capability against armored targets and its aftereffects. During penetration, an EFP generates intense light and heat effects, as well as a large number of high-speed fragments. These high-temperature, high-speed fragments formed by EFP fragmentation and armor material shedding are called "back-target fragments" or "secondary fragments." In fact, after EFP penetrates armor, the primary threat to equipment and personnel inside the armored target comes largely from back-target fragments; these fragments are the main damaging agents inflicting damage on targets inside the armor. Therefore, studying the destructive capability of back-target fragments on targets behind the target is crucial for assessing the destructive power of an EFP warhead.

[0003] In his article "Fragmentation Characteristics After Vertical Penetration of a Steel Plate Target by Explosive Formed Projectiles," Xing Baiyang studied the fragmentation behind the target formed by EFP vertical penetration of a steel plate, analyzing the relationship between the number of fragments and their dispersion angle. However, he did not address the damage process of the fragments to the verification target, making it impossible to assess the destructive capability of the EFP fragments. In his article "Experimental Study on the Aftereffect Fragment Cloud of Explosive Formed Projectiles Penetrating a Steel Target," Wang Xin used experimental methods to analyze the perforation of the target fragments on a verification aluminum plate, obtaining the dispersion angle and penetration power of the fragments. He also statistically analyzed the number of fragments in different zones of the verification target. However, the experimental method only yielded a small amount of information on the damage caused by the fragments to the verification target, and it was impossible to distinguish the source of the fragments that caused the perforation. Summary of the Invention

[0004] The purpose of this invention is to provide a visualization method for evaluating the damage capability of EFP target fragments. Based on the velocity, mass, and scattering direction of the target fragments, and combined with the fragment penetration theory, the method performs zonal statistical analysis on the aftereffect damage characteristic parameters such as the number of fragments, fragment mass, fragment distribution density, and fragment energy distribution density in different scattering angle intervals. This method can intuitively reflect the distribution of target fragments on the verification target and the damage to the verification target.

[0005] The technical solution for achieving the objective of this invention is: a visualization method for evaluating the post-target fragmentation damage capability of EFP, comprising the following steps:

[0006] Step 1: Based on the numerical simulation results of the EFP target fragments, extract the mass, velocity, and position information of all target fragments, and construct the fragment information matrices of EFP and target plate respectively.

[0007] Step 2: Establish a calculation model for the impact angle of the fragments behind the target on the verification target. Based on the THOR equation and combined with the velocity, mass, and impact angle information of the fragments behind the target, calculate the limit velocity of all fragments behind the target penetrating the verification target plate of the specified material and thickness.

[0008] Step 3: Based on the limit velocity of the fragments penetrating the target, filter out the fragments with destructive capabilities and construct an effective fragment information matrix for the EFP and the target plate.

[0009] Step 4: Based on the distance between the main target plate and the verification target, divide the verification target into zones according to the 0°-90° scatter angle range, and calculate the fragment information behind the target in each scatter angle interval, including the total mass of fragments, the total number of fragments, the fragment distribution density, and the fragment energy distribution density.

[0010] Step 5: Based on the fragment information behind the target within different scattering angle intervals obtained in Step 4, calculate the radius of the damaged area, the area of ​​the damaged area, and the maximum scattering angle of the fragment behind the target on the verification target. Combine these with the fragment information behind the target to form the characteristic parameters of the damage caused by the fragment behind the target.

[0011] Step 6: Write the post-target fragment damage characteristic parameters into the fragment distribution matrix and output a text file, and display the distribution position of the post-target fragments on the verification target and the damage area.

[0012] Compared with the prior art, the present invention has at least the following significant advantages:

[0013] (1) The damage of the back fragments to different verification targets was considered, which can indirectly reflect the damage capability of the back fragments to different types of back targets.

[0014] (2) Compared with experimental statistics, this method can obtain a large amount of information on the aftereffect damage characteristics of the target to the verification target by the target fragments, which can intuitively reflect the damage of the target fragments to the verification target, and can also distinguish the source of the target fragments that cause the verification target to perforate. Attached Figure Description

[0015] Figure 1 This is a flowchart of a visualization method for evaluating the destructive power of EFP target fragments according to the present invention.

[0016] Figure 2 This is a schematic diagram of the target penetration verification process of post-target fragments in an embodiment.

[0017] Figure 3 This is a schematic diagram showing the distribution of the fragments behind the target on the verification target in the embodiment. Detailed Implementation

[0018] Combination Figure 1A visualization method for evaluating the fragmentation capability of EFP targets includes the following steps:

[0019] Step 1: Based on the numerical simulation results of the EFP target fragments, extract the mass, velocity, and position information of all target fragments, and construct the fragment information matrices of EFP and target plate respectively.

[0020] The numerical simulation results of EFP target fragments are derived from the calculation results of LS_DYNA and AUTODYN; the first column of the fragment information matrix is ​​the target fragment number i, and the second column is the target fragment mass m. fi Columns 3-6 represent the velocity components v of the fragments behind the target on the x, y, and z axes, respectively. xi v yi v zi and the resultant velocity v fi Columns 7-9 represent the coordinate components x, y, and z of the fragment behind the target, respectively. i y i z i .

[0021] Proceed to step 2.

[0022] Step 2: Establish a calculation model for the impact angle of the fragments behind the target on the verification target, and calculate the limit velocity of all fragments behind the target penetrating a verification target plate of a specific material and thickness.

[0023] The specific calculation model for the impact angle of the fragment behind the target on the verification target is as follows:

[0024]

[0025] In equation (1), v xi Let v be the velocity component in the x-direction of the i-th fragment. yi Let v be the velocity component in the y-direction of the i-th fragment. zi Let θ be the velocity component in the z-direction of the i-th fragment. i The angle at which the fragments land on the verification target after being hit.

[0026] The angle at which the fragment behind the target lands on the verification target is the angle between the velocity direction of the fragment behind the target and the normal of the verification target.

[0027] The ultimate velocity v of the target plate, where fragments penetrate a specified material and thickness, is verified. bi as follows:

[0028]

[0029] In equation (2), i represents the sequence number of the fragment after the i-th target, t0 is the thickness of the verification target, and s i Let m be the target area of ​​the i-th fragment.fi For the quality of the i-th slice, θ i α1, β1, γ1, and λ1 are the target angles of the fragments after the target strike on the verification target. c1, α1, β1, γ1, and λ1 are the material properties of the verification target, and their specific values ​​depend on the material of the verification target.

[0030] Proceed to step 3.

[0031] Step 3: Based on the limit velocity of the fragments penetrating the target, filter out the fragments with destructive capabilities and construct an effective fragment information matrix for the EFP and the target plate.

[0032] First, the target fragment obtained in step 2 is used to penetrate a specified material and a specified thickness to verify the ultimate velocity v of the target plate. bi Write it into the 10th column of the fragment information matrix.

[0033] Secondly, compare the target fragment limit velocity v. bi Combined velocity v of the fragments after the target fi The size of the target fragments and their velocity v fi >v bi If the fragment can penetrate the verification target, record the corresponding fragment number; if the combined velocity of the fragments behind the target is v... fi <v bi If the target cannot be penetrated, it means that the fragment cannot penetrate the verification target. Continue reading the next fragment until all fragments behind the target have been read. Finally, extract the fragment information behind the target corresponding to the recorded fragment number to construct a valid fragment information matrix.

[0034] Typically, the number of fragments in the effective fragment information matrix is ​​less than the number of fragments in the fragment information matrix. This is because whether a fragment can penetrate the verification target depends on the target material, thickness, and the fragment's velocity, mass, and impact angle. When fragments are more likely to penetrate the verification target, the number of effective fragments is greater.

[0035] Proceed to step 4.

[0036] Step 4: Based on the distance between the main target plate and the verification target, divide the verification target into zones according to the 0°-90° scatter angle range, and calculate the fragment information behind the target in each scatter angle interval, including the total mass of fragments, the total number of fragments, the fragment distribution density, and the fragment energy distribution density.

[0037] The radius of the partition for the verification target within the 0°-90° scatter angle range is:

[0038] r j =L·tan(α) j / twenty three)

[0039] In equation (3), r jTo verify the radius of the j-th region on the target, L is the distance between the back of the main target plate and the front of the verification target, and α is... j To verify the fragment scattering angle behind the target corresponding to the j-th region on the target, α j =10°, 20°, 30°,...90°, j=1, 2, 3,...9.

[0040] First, calculate the time t required for the fragment behind the target to move from its current position to the surface in front of the verification target.

[0041] Then, the coordinate position (x′) corresponding to the fragment moving from the target to the front surface of the verification target is calculated. i ,y′ i ), y′ i =y i +v yi ·t、z′ i =z i +v zi ·t;

[0042] Finally, the distribution radius r of the fragments behind the target on the verification target was calculated. i ,

[0043] By comparing the target fragment distribution radius r i With the verification target partition radius r j The relationship between the fragments was used to obtain fragment information located in different scatter angle intervals.

[0044] The total mass M of the fragments behind the target within each dispersion angle range j as follows:

[0045]

[0046] M j To verify the total mass of the target fragments distributed in the j-th region on the target, m i,j To verify the quality of the i-th fragment in the j-th region of the target.

[0047] The total number of target fragments N in each dispersion angle interval j as follows:

[0048] N j =|A j | (5)

[0049] N j To verify the total number of target fragments distributed in region j on the target, A j To verify the set of fragment elements in region j of the target;

[0050] Target fragment distribution density within each dispersion angle range as follows:

[0051]

[0052] Energy distribution density E of fragments behind the target within each dispersion angle range Kj as follows:

[0053]

[0054] Proceed to step 5.

[0055] Step 5: Based on the fragment information behind the target within different scattering angle intervals obtained in Step 4, calculate the radius of the damaged area, the area of ​​the damaged area, and the maximum scattering angle of the fragment behind the target on the verification target.

[0056] The radius of the damaged area is taken as the radius r of the minimum envelope circle on the verification target containing 95% of the effective fragments. b The damaged area S is:

[0057]

[0058] Maximum fragment dispersion angle α behind the target max for:

[0059]

[0060] Proceed to step 6.

[0061] Step 6: Write the post-target fragment damage characteristic parameters into the fragment distribution matrix and output a text file, and display the distribution position of the post-target fragments on the verification target and the damage area.

[0062] The columns of the fragment distribution matrix are as follows: verification target partition number, total mass of fragments behind the target, total number, fragment distribution density, fragment energy distribution density, radius of the damaged area, area of ​​the damaged area, and maximum scattering angle. The distribution position of the fragments behind the target on the verification target is displayed as dots of different sizes according to their mass. Solid dots represent the perforations of the fragments behind the target generated by EFP on the verification target, and hollow dots represent the perforations of the fragments behind the target generated by the target plate on the verification target. The damaged area is displayed as a circular area enclosed by the minimum envelope circle.

[0063] Example 1

[0064] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only one specific embodiment of the present invention. All other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0065] This invention discloses a visualization method for evaluating the destructive power of EFP target fragments as follows:

[0066] Step 1: Taking the numerical simulation results of a tantalum alloy EFP penetrating a 50mm thick armor steel vertically at a speed of 2000m / s as an example, extract the mass, velocity and position information of all target fragments, construct the fragment information matrix of EFP and target plate respectively, and proceed to Step 2.

[0067] Step 2: Establish a calculation model for the impact angle of the fragment behind the target on the verification target. A schematic diagram of the impact angle of the fragment behind the target on the verification target is shown below. Figure 2 The ultimate velocity of all target fragments penetrating a specified material and thickness of a verification target plate was calculated. The target material, thickness, and target material property parameters are shown in Table 1.

[0068] Table 1 Parameters of the Target Material

[0069]

[0070] Proceed to step 3.

[0071] Step 3: Based on the limit velocity of the fragments penetrating the target, filter out the fragments with destructive capabilities, construct the effective fragment information matrix of EFP and target plate, and proceed to Step 4.

[0072] Step 4: Based on the distance between the main target plate and the verification target, here the distance between the main target plate and the verification target is taken as L = 120cm. Divide the verification target into zones according to the 0°-90° scatter angle range, calculate the fragment information behind the target in each scatter angle interval, including the total mass of fragments, the total number of fragments, the fragment distribution density, and the fragment energy distribution density, and then proceed to step 5.

[0073] Step 5: Based on the fragment information behind the target within different scattering angle intervals obtained in Step 4, calculate the radius of the damaged area, the area of ​​the damaged area, and the maximum scattering angle of the fragment behind the target on the verification target. Combine the fragment information behind the target to form the characteristic parameters of the damage after the fragment behind the target, and proceed to Step 6.

[0074] Step 6: Write the post-target fragment damage characteristic parameters into the fragment distribution matrix and output a text file, and display the distribution position of the post-target fragments on the verification target and the damage area.

[0075] Finally, the distribution of the fragments behind the target on the verification target was obtained as follows: Figure 3 As shown in the figure, the characteristic parameters of post-target fragment damage are shown in Table 2.

[0076] Table 2. Parameters of post-target fragmentation damage characteristics

[0077]

Claims

1. A visualization method for evaluating the fragmentation damage capability of an EFP target, characterized in that, The specific steps are as follows: Step 1: Based on the numerical simulation results of the EFP target fragments, extract the mass, velocity, and position information of all target fragments, and construct the fragment information matrices of EFP and target plate respectively. Step 2: Establish a calculation model for the impact angle of the target fragments on the verification target. Based on the THOR equation and combined with the velocity, mass, and impact angle information of the target fragments, calculate the limit velocity of all target fragments penetrating the verification target plate of the specified material and thickness. Step 3: Based on the limit velocity of the fragments penetrating the target, filter out the fragments with destructive capabilities and construct the effective fragment information matrix of EFP and target plate. Step 4: Based on the distance between the main target plate and the verification target, divide the verification target into zones according to the 0°-90° scatter angle range, and calculate the fragment information behind the target in each scatter angle interval, including the total mass of fragments, the total number of fragments, the fragment distribution density, and the fragment energy distribution density. Step 5: Based on the fragment information behind the target within different scattering angle intervals obtained in Step 4, calculate the radius of the damaged area, the area of ​​the damaged area, and the maximum scattering angle of the fragment behind the target on the verification target. Combine these with the fragment information behind the target to form the characteristic parameters of the damage aftereffect of the fragment behind the target. Step 6: Write the post-target fragment damage characteristic parameters into the fragment distribution matrix and output a text file, and display the distribution position of the post-target fragments on the verification target and the damage area.

2. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 1, characterized in that, In step 1, the numerical simulation results of EFP target fragments are derived from the calculation results of LS_DYNA and AUTODYN; the first column of the fragment information matrix is ​​the target fragment number i, and the second column is the target fragment mass m. fi Columns 3-6 represent the velocity components v of the fragments behind the target on the x, y, and z axes, respectively. xi v yi v zi and the resultant velocity v fi Columns 7-9 represent the coordinate components x, y, and z of the fragment behind the target, respectively. i y i z i .

3. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 2, characterized in that, In step 2, a calculation model is established for the impact angle of the target fragments on the verification target. The ultimate velocity of all target fragments penetrating the verification target plate of a specified material and thickness is calculated, as follows: The specific calculation model for the impact angle of the fragment behind the target on the verification target is as follows: In equation (1), v xi Let v be the velocity component in the x-direction of the i-th fragment. yi Let v be the velocity component in the y-direction of the i-th fragment. zi Let θ be the velocity component in the z-direction of the i-th fragment. i The angle at which the fragments land on the verification target after being struck; The ultimate velocity v of the target plate, where fragments penetrate a specified material and thickness, is verified. bi as follows: In equation (2), t0 is the thickness of the verification target, and s i Let m be the target area of ​​the i-th fragment. fi Let θ be the mass of the i-th fragment. i α1, β1, γ1, and λ1 are the target angles of the fragments after the target strike on the verification target. c1, α1, β1, γ1, and λ1 are the material properties of the verification target, and their specific values ​​depend on the material of the verification target.

4. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 3, characterized in that, In step 3, the construction of the effective fragment information matrix is ​​based on the fragment information matrix in step 1, as detailed below: First, the target fragment obtained in step 2 is used to penetrate a specific material and a specific thickness to verify the ultimate velocity v of the target plate. bi Write it into the 10th column of the fragment information matrix; Secondly, compare the target fragment limit velocity v. bi Combined velocity v of the fragments after the target fi The size of the target fragments and their velocity v fi >v bi If the fragment can penetrate the verification target, record the corresponding fragment number; if the combined velocity of the fragments behind the target is v... fi <v bi If the fragment cannot penetrate the verification target, continue reading the next fragment until all fragments behind the target have been read. Finally, the target fragment information corresponding to the recorded fragment serial numbers is extracted to construct an effective fragment information matrix.

5. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 4, characterized in that, In step 4, the target fragment information within each scattering angle interval is calculated, including the total fragment mass, total number, fragment distribution density, and fragment energy distribution density, as detailed below: The radius of the partition for the verification target within the 0°-90° scattering angle range is: r j =L·tan(α j / 2) (3) In equation (3), r j To verify the radius of the j-th region on the target, L is the distance between the back of the main target plate and the front of the verification target, and α is... j To verify the fragment scattering angle behind the target corresponding to the j-th region on the target, α j =10°, 20°, 30°,…90°, j=1, 2, 3,…9; First, calculate the time t required for the fragment behind the target to move from its current position to the surface in front of the verification target. Then, the coordinate position (x′) corresponding to the fragment moving from the target to the front surface of the verification target is calculated. i ,y′ i ), y′ i =y i +v yi ·t、z′ i =z i +v zi ·t; Finally, the distribution radius r of the fragments behind the target on the verification target was calculated. i , By comparing the target fragment distribution radius r i With the verification target partition radius r j The relationship between the fragments was used to obtain fragment information located in different scatter angle intervals; The total mass M of the fragments behind the target within each dispersion angle range j as follows: M j To verify the total mass of the target fragments distributed in the j-th region on the target, m i,j To verify the quality of the i-th fragment in the j-th region of the target; The total number of target fragments N in each dispersion angle interval j as follows: N j =|A j | (5) N j To verify the total number of target fragments distributed in region j on the target, A j To verify the set of fragment elements in region j of the target; Target fragment distribution density within each dispersion angle range as follows: Energy distribution density E of fragments behind the target within each dispersion angle range Kj as follows:

6. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 5, characterized in that, In step 5, the radius of the damaged area, the area of ​​the damaged area, and the maximum scattering angle of the fragments behind the target on the verification target are calculated, as follows: The radius of the damaged area is taken as the radius r of the minimum envelope circle on the verification target containing 95% of the effective fragments. b The damaged area S is: Maximum fragment dispersion angle α behind the target max for: Where L is the distance between the back of the main target plate and the front of the verification target.

7. The visualization method for evaluating the post-EFP target fragmentation damage capability according to claim 6, characterized in that, In step 6, the columns of the fragment distribution matrix are as follows: verification target partition number, total mass of fragments behind the target, total number, fragment distribution density, fragment energy distribution density, radius of the damaged area, area of ​​the damaged area, and maximum scattering angle. The distribution position of the fragments behind the target on the verification target is displayed as dots of different sizes according to their mass. Solid dots represent perforations of the fragments behind the target generated by EFP on the verification target, and hollow dots represent perforations of the fragments behind the target generated by the target plate on the verification target. The damaged area is displayed as a circular area enclosed by the minimum envelope circle.

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