A Study On The Numerical Algorithms Of Behind Armor Debris And Its Aftereffects

Behind armor debris, resulting from the perforation of armored equipment by apenetrator, bullet or fragment, is a collection of fragments (projectile fragments and armorfragments) flying forward behind the armor at a high speed. The large number of behindarmor debris form a shape of elliptical cone with its vertex on the perforation of the armorand advance secondary damage to the personnel and equipment inside. It is meaningful tostudy on the generation of behind armor debris and its aftereffects for protection ofarmored equipment and structural optimization of kinetic energy penetrator.The behind armor debris’generation and aftereffect can be divided into three stages:1)armor-piercing process of kinetic energy projectiles;2) dynamical generation of behindarmor debris; and3) the damage of behind armor debris to equipment and personnel inside.At present, many commercial software have been able to simulate the armor-piercingprocess of kinetic energy projectiles. However, no software can simulate the wholeprocess of generation of behind armor debris and its aftereffects.Based on existing three-dimensional nonlinear dynamic finite element software, thisthesis proposed an algorithm considering the generation of behind armor debris of ductilematerial and its aftereffects. Firstly, track the state parameters of projectile and targetelements during the armor-piercing process. Once an element meets the failure criterion,the size of the behind armor debris can be determined by the fragment formation theoryduring this time step. According to the failure elements’ equivalent volume, one can splitor merge the failure elements to generate discrete fragments, and the topology of theelements can be changed dynamically. Then the generated discrete fragments inherit theirparent’s state parameter and are considered in the following simulation, use master-slavesurfaces searching algorithm to update the contact interface of fragments, adopt penaltyfunction method to calculate contact forces between fragments and continuum, and determine whether fragments fail or not.Numerical examples show that the proposed algorithm provides a good approach tosimulate the dynamical generation of behind armor debris and the damage of theequipment and personnel inside accurately. This algorithm lays a foundation fordeveloping a complete edition of behind armor debris software.