NUMERICAL STUDY OF DYNAMIC PROPERTIES OF A SELECTED MATERIAL LAYER OF BULLETPROOF SHIELDS

摘要

Impact protection systems are currently constructed from several layers of materials with different mechanical properties. The purpose of such a system is to stop the projectile after hitting and also to minimize the damage to the inner layers of the shield caused by the impact. The frontal layer plays a significant role in the deceleration of the impact mass. This layer must be made of a material with appropriate elastic properties. It is necessary to create a suitable theoretical model (mechanical model) and analyze it to design an effective material system. In this test a theoretical dynamic model of the protective structure is adopted for the elastic-damping dynamic system. The model assumes that two parameters are responsible for the projectile braking efficiency in the frontal layer. These are such coefficients as dry friction (h) and viscous friction (η), which occur in a function describing the braking force of an appropriate form. Their values were estimated using a numerical method, where the limiting time of projectile braking in the frontal layer of the analyzed material and the braking distance were determined. These two values obtained by means of numerical simulation methods with the use of ABAQUS program allowed verifying the usefulness of the proposed identification method. The range of calculations was performed on the composite material samples made of rubber material - SBS rubber waste combined with polyurethane resin. The penetration of samples was simulated with M43 7.62 mm projectile core.