Numerical results and analysis of the hottest sphe

2022-09-22
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Numerical calculation results and analysis of spherical fragment penetrating gelatin

numerical calculation results and analysis of spherical fragment penetrating gelatin

through the simulation calculation of penetration, the velocity, displacement diagram and total energy attenuation curve of fragment movement can be obtained. We can see the light and rigid plastic tube, and fragment penetrating gelatin target belongs to the movement with relatively fast energy attenuation. At the same time, the following conclusions can be drawn from the analysis of the above figure:

(1) during the penetration process of fragments into the target plate, the cavity formed by fragments penetrating gelatin can be clearly seen. It can be seen from the observed shear stress diagram that during the penetration process, the stress in the contact part between the fragment and the target plate is very large, and the stress acting on

is very small beyond the distance of 2 ~ 3 times the projectile diameter. Taking the impact point as the center of the circle, it diffuses to the four stages to form a cavity, which conforms to the classification standard of penetration type according to velocity

the instantaneous cavity and permanent cavity formed in the process of penetrating gelatin have the following definitions and descriptions

permanent cavity is the tissue defect area formed by the bullet passing through the tissue and the instantaneous cavity after the bullet is fired into the human target. The permanent cavity is filled with seeping objects such as fire living tissue and blood, and the distance between clamps is 50mm, as well as foreign matters brought in or inhaled by projectiles or instantaneous space-time cavities. The size, shape and trajectory of the permanent cavity depend on the nature of the projectile. Instantaneous cavity is a large instantaneous cavity after the projectile enters the muscle at a relatively high speed. Its volume is more than 20 times larger than that of the permanent wound

(2) in the process of penetrating gelatin, due to the erosion and spalling of spherical fragment materials, the fragment strain energy is correspondingly reduced, which is conducive to the penetration. During the penetration process, the fragments have obvious plastic deformation and mass attenuation, are easy to wear, and the perforation trajectory at the exit changes, which is completely consistent with the reality

(3) the velocity of fragments attenuates significantly during the penetration process. After the penetration process, the residual velocity of fragments attenuates to zero, and the total energy also tends to decay, and it reaches stability with time. The displacement basically changes linearly until it stays in the target plate

(4) through analysis, it can be seen that under this target angle, increasing fragment speed will increase the penetration power and reduce the possibility of projectile jumping

(5) from the numerical calculation results given above, the basic coincidence of the calculation results can be a good way to find out the process performance of relevant products and the internal defects of the manufacturer's products. The simulation results can provide an important basis for structural optimization design

conclusion

in this paper, the three-dimensional numerical simulation of the penetration process of spherical fragments into gelatin targets is carried out by using the large-scale finite element analysis software ANSYS/LS-DYNA, and the velocity attenuation curve, displacement curve, total energy attenuation curve and the instantaneous cavity formed are obtained. The stress changes of spherical fragments and target plates are obtained, which can well describe the impact dynamic response, and is basically consistent with the experimental data

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