NPR effect on energy absorption enhancement of star-shaped honeycomb filled shear thickening fluids under impact

Abstract

Porous materials filled with shear thickening fluids (STF) can adapt flexibly to complex dynamic loadings environments, showing great promise as an advanced composite material with high impact resistance. However, the energy absorption performance of these STF related materials is not fully exploited due to the low coupling efficiency between the STF and the structure. In this paper, the dynamic compressive behavior of STF filled star-shaped honeycombs (SSH) with significant negative Poisson's ratio (NPR) effect was studied using modified SHPB experiments and finite element (FE) simulations. The coupling mechanism between the NPR effect and the shear-thickening behavior of STF is analyzed. The dynamic mechanical performance of the STF-filled SSH (SSH-STF) under initial velocity impact and constant velocity compression loading, including stress distribution, energy dissipation, and coupling strength, is comprehensively analyzed. The results indicate that SSH-STF enhances energy absorption efficiency by the mutual extrusion effect of SSH and STF, which limits local deformation and modifies the unstable deformation mode of SSH, while also expanding the energy absorption region. The shear thickening effect of STF limits 82 % of the in-plane rotation behavior of SSH-STF unit cells compared to unfilled SSH under high-velocity impact, promoting uniform and sufficient contraction deformation across the unit cells, which enhances the mean crushing force by 253 %. Meanwhile, the shear thickening behavior of STF leads to faster stress transfer within SSH, significant enhancement of the local deformation stability and effectively increasing the critical impact velocity of the SSH-STF. In this paper, the significant enhancement of energy absorption performance of the STF-SSH composite provides valuable insights for the design of STF-filled auxetic honeycomb structures in practical applications.