Impact properties of uniaxially thermoformed auxetic foams

This work describes large strain quasi-static and impact tests of a new class low-cost, uniaxially thermoformed, transverse isotropic auxetic foams with compression ratio ranging from 20 to 80%. A custom drop tower rig high-speed cameras suitable for these soft porous foam materials is designed used perform energy 0.38 1.90 J, corresponding rates 64/s 143/s. The thermoformed only show auxeticity when loaded along the direction uniaxial thermoforming compression, Poisson's V21 reaching as low ?1.5 at 20% then close 0 strains. samples deform shear band deformations, also due auxeticity. negative that enhanced absorption performance, normalized peak force reduction high ?40% against pristine foam; however direction. constitutive model based on Nagy's approach applied describe enhancement dynamic stress during compared one, rate effects.