Dynamic deformation of copper-jacketed lead bullets captured by high speed digital image correlation

Abstract

The development of high fidelity simulations of lead-cored bullet impacts on soft body armor, motivated by the need for improved armor designs and performance standards for law enforcement, requires accurate models for both the armor and the deformable bullet. This paper examines the ability of the Johnson-Cook constitutive model to predict the dynamic deformation of a 0.357 caliber copper-jacketed lead-cored slug subjected to a direct-impact Kolsky Bar test. A high speed 3D Digital Image Correlation (DIC) technique is used to measure the deformation history of the slug subject to an impact velocity of 15.3 m/s and an impact energy of 62.5 J, which is about 6.5 % of the impact energy required in NIJ Standard 0101.04 for testing Type Il body armor with this bullet. The DIC results and force history data are compared to finite element simulations of the test. A sensitivity analysis of the material parameters is carried out to determine their relative influence on the deformation and force history response, and improved parameter values are identified and compared to the baseline values. ©2010 Society for Experimental Mechanics Inc.