Simulation of ballistic test for personal body armor

Objective of this thesis is to simulate costly personal body armor tests, with an additional ambitious desire to design a Level IV vest. The thesis starts with an introduction covering history of personal body armors, objectives and motivation, problem statement and methods, ballistic protection, and classification of body armor, usage areas, ballistic testing and back face signature, classification of failure modes, composite, and ceramic materials properties. Then, sixty two reviewed articles are summarized in literature survey chapter. Since the simulation studies require analytical models to be used in terminal ballistics, the selected sixteen models are explained. Perforation of target by a penetrator takes a time at microsecond level, a special engineering analysis software, LS DYNA, which is one of the most widely used finite element software tool for high strain rate applications, is used in the studies. Therefore, basic introductory information for the use of the software, material models and all necessary steps of the program are introduced to facilitate the understanding of simulation studies conducted within the scope of this thesis, and to provide a guide to the new users of the software. Since most of the research data on terminal ballistics are on metallic armor plates, seven publications made on metal target penetration and two publications on composite perforation are restudied by using LS DYNA. It took long time to get solutions which are close to the test data from the literature, and they are summarized. It seems that the capability of LS DYNA in simulating the real firing tests are very high and can be used as a backup for costly real firing tests. A parametric study is conducted to see effect of some parameters, such as plate thickness, strength of plate material, nose geometry of the penetrator, etc. on the ballistic performance. Collision analyses are performed for different ceramic and Ultra High Molecular Weigh Polyethylene (UHMWPE) thicknesses. In addition, steel and aluminum materials are placed behind the ceramic plates to observe that the projectiles at different velocities can be slowed down. Bulletproof vest is based on NIJ standard and it contains several level protection against different projectile types. A lengthy study is conducted to design a vest with Level IV ballistic protection against 7.62 mm M2AP projectile. Firstly, simulation studies are carried out by using Kevlar 29 and Dyneema (UHMWPE), showing that UHMWPE has better performance. Therefore, further studies are made with UHMWPE at different thicknesses till 36.8 mm to reach a complete protection. Similar studies are realized with ceramics, such as Alumina and Boron Carbide. Hybrid usage of Alumina with UHMWPE shows synergy effect. However, it does not seem to be possible to design a vest at Level IV protection level, within acceptable weight and back face signature limits. Also, different conditions are investigated for parametric analyses and ballistic limit velocities are calculated by using by Recht – Ipson analytical model. Although, it is intended to do the simulation studies at all protection levels, but only at some levels are carried out due to unavailability of real firing test data.