26 Sep 2024

High-Rate Characterization and Modeling of a Hyperelastic Block Copolymer Subjected to Ballistic Impact

Abstract: A polystyrene-polyisobutylene-polystyrene star-block copolymer (PS-PIB-PS) is a thermoplastic elastomer with visco hyperelastic characteristics that displays a high level of toughness and performs well in shock attenuating applications. The research goal is to investigate experimentally and numerically the capacity of PS-PIB-PS to dissipate kinetic energy and examine its deformation and failure modes under impact by spherical steel projectiles at speed ranges of 200–1,700 m/s. First, PS-PIB-PS is characterized using a Split-Hopkinson Pressure Bar to measure high strain rate response and calibrate a hyperelastic material model. Second, ballistics tests are conducted on 12 in. × 12 in. PS-PIB-PS targets with various thicknesses to determine the ballistic limit and residual velocity (Vr) versus impact velocity (Vi) relationship. Finally, ALE3D is used to model the ballistic response and capture the extreme deformation observed during testing. During ballistic impact tests, significant deformation occurred on the backside of polymer targets, followed by perforation of the polymer, culminating with retraction and recovery of the polymer in a self-healing manner. Numerical simulations captured the deformation behavior during impact and predicted the Vr versus Vi response with high accuracy. This research provides a method of modeling hyperelastic materials subjected to ballistic impact and provides a better understanding of energy dissipation of these materials.