Highly strain-rate sensitive and ductile composite materials combining soft with stiff TPMS polymer-based interpenetrating phases

Abstract

The current work investigates the engineering of strain-rate sensitive and ductile composites through the combination of stiff, triply-periodic-minimal-surface (TPMS) with soft, rubber-type material phases. Different interpenetrating phase composite (IPC) designs are considered, with Diamond, Fisher-Koch, and IWP TPMS architectures as reinforcement phase topologies. The loading rate sensitivity of the arising IPCs is evaluated at different strain-rates, revealing an effective composite performance that well separates from the either brittle or substantially low-strength behavior of its constituent materials. Significant strain-rate effects are recorded, which relate to increased stiffness and energy absorption attributes upon substantial ductility, with the actual performance to depend on the underlying reinforcement phase topology. The effective strain-rate IPC constitutive response is well-captured by dedicated, low numerical cost and high accuracy machine learning models, whereas Digital Image Correlation (DIC) and finite element analysis are employed to provide insights in the inner strain and stress fields developed and failure modes observed. Overall, energy absorptions higher than 10 and up to 14 MJ m−3 are reported for strain-rates in the order of 100, furnishing specific energy absorptions (SEA) in the uppermost range of the effective composite material behaviors up to now reported, upon exceptionally high crushing force efficiencies (CFE) at moderate densities.