Strut and stochastic polymer reinforcement interpenetrating phase composites: Static, strain-rate and dynamic damping performance

The current work investigates the static, strain-rate and dynamic damping performance of interpenetrating phase composites (IPCs) engineered with polymer-based, isotropic, strut and stochastic reinforcement phase metamaterial topologies. In particular, BCC, random function and spinodal-based, polymer-rubbery phase IPC designs are investigated. Their specific energy absorption (SEA) and crush force efficiency (CFE) are assessed over different loading rates and compared to the ones reported for a wide range of existing architected advanced materials. It is shown that spinodal-based IPC designs outperform most comparable density advanced materials at increased loading rates, yielding SEA values that approach 16 J/g, combined with 90% CFE values. The mechanism allowing for the high strain-rate sensitive and ductile performance is first explicated. Moreover, machine learning modeling is employed to assess the significance of the underlying influential design parameters of the investigated polymer-based IPCs. The results indicate that the reinforcement phase type is nearly two times more important than the reinforcement phase content at higher strain rates, with a nearly loading-rate insensitive effect on the constitutive response. The dynamic damping performance of the architected composites is superior than the one obtained for the underlying reinforcement phase, while it depends on the reinforcement phase. For all designs, the loss modulus increases over a broad range of frequencies, contrary to the negative damping-frequency dependence recorded for the underlying reinforcement phase. The results are expected to serve as a reference in the analysis and design of polymer-based, multiphase interpenetrating phase composites, with reinforcement topologies and viscoelastic attributes beyond the ones here considered.