The internal deformation evolution of the ceramic/UHMWPE laminate body armor backface under ballistic impact

Abstract

The ceramic/ultra-high-molecular-weight polyethylene (UHMWPE) laminated composite body armor absorbs bullet impact energy through ceramic fragmentation and deformation of the laminate, thus protecting the human body. However, much attention has been focused on energy absorption in the impact direction (z-axis), while energy absorption in the in-plane directions (x and y axes), caused by the traction between fiber bundles due to cohesive forces, has been overlooked. Therefore, this paper conducts an in-depth study of the x and y direction deformation, traction velocity, and energy conversion on the back surface of the body armor after impact. First, the fiber traction curves in the x and y directions show bell-shaped profiles. By taking the derivative of the traction curves and using 50% of the maximum derivative width as the boundary, the maximum traction velocity is found to be 739.80 m/s, and the profiles exhibit the characteristics of an exponential function under different boundary widths. Secondly, setting fixed constraints around the impacted ceramic fragments can better simulate the extrusion and fracture of the equivalent layer on the contact surface, with minimal impact on the formation of cracks, spalling, and bulging. Finally, the bullet's kinetic energy decreases by 84.21%, in which mostly converting into the ceramic's kinetic and internal energy, with a small portion converting into the laminate's kinetic and internal energy. These findings are crucial for revealing the internal mechanistic details of the ceramic/UHMWPE composite under impact response in the x and y directions and for assessing the applicability of numerical simulations.

Keywords

• Ceramics/UHMWPE laminate composite
• Backface U and V profile
• SPH-FEM coupled model
• Contact condition
• Energy transformation