AUXETIC SANDWICH PANELS FOR PROTECTION AGAINST IMPACT LOADS

Abstract

This study investigates the dynamic behavior of sandwich protective panels with non-auxetic and auxetic cellular cores under low-velocity impacts. 2.5D cellular core topologies are introduced that comprise a conventional non-auxetic honeycomb (HC) core architecture, along with four auxetic designs: re-entrant (RE), double arrow head (DAH), standard chiral (SC), and wavy chiral (WC). Dynamic Finite Element Method (FEM) analyses are performed using Abaqus/Explicit, and their accuracy is verified through experimental and numerical data. To assess the overall performance under general loading conditions, a comprehensive investigation is conducted, encompassing direct impact, oblique impact and offset impact. A novel method for evaluating the protective effectiveness is developed, named the `cushion time' and `cushion depth'. The results suggest that auxetic designs display a more pronounced advantage, particularly at higher velocities. Moreover, WC design consistently demonstrates exceptional performance during low-velocity impacts under various loading conditions, regardless of the incident velocity, direction, or location.