Plate materials for cardiopulmonary protection: a computational modeling study

Personal body armor, such as ballistic protective plates (BPPs), plays a vital role in protecting the torso against high-energy impacts, yet Behind Armor Blunt Trauma (BABT) remains a concern. BABT can inflict damage on critical organs, particularly the heart and lungs. This study investigates the protective performance of BPP materials and padding configurations. We employed a finite element (FE) model of the torso, incorporating detailed anatomical features, to simulate non-penetrating impacts on the heart and lungs. Three BPP materials - Kevlar-29, Ultra-High-Molecular-Weight Polyethylene (UHMWPE), and Alumina, were analyzed with and without 6 mm and 12 mm padding layers against a 5.56 mm bullet impact at 500 m/s. The results demonstrated that Alumina plates provided superior protection, resulting in 186% lower peak strain and 229% lower peak stress in the heart compared to Kevlar and UHMWPE. The addition of padding further reduced strains and stresses, with 12 mm padding yielding average reductions of 44% in peak strain and 36% in peak stress in the heart. Similarly, in the lungs, 12 mm padding led to reductions of 38% in peak strain and 34% in peak stress. The model was validated against experimental force measurements using a life-sized torso phantom, demonstrating strong agreement with piezoelectric sensor measurements (less than 4% difference). These findings underscore the importance of selecting appropriate BPP materials and padding thickness to minimize biomechanical impacts on vital organs.