investigation of post-buckling, energy harvesting, and relaxation of shape memory auxetic structure with thermo-visco-hyperelastic modeling

This study investigated the non-linear post-buckling behavior of an auxetic cellular structure under compressive loading, with variations in temperature and strain rate. simulations were conducted on epoxy shape memory polymer (smp) incorporating different geometrical imperfections derived from buckling analysis. a hyper-viscoelastic model, coupled with the williams-landel-ferry (wlf) equation, was employed, enabling thermo-hyper-viscoelastic modeling that accounts for temperature dependency. the results demonstrated that the imperfection factor significantly changes the shape transformation, and an imperfection factor of 0.01 was used for subsequent simulations. it was observed that increasing the temperature up to 50 °c increases the critical strain required for pattern transformation, while further temperature increases lead to a decrease in the critical strain. additionally, increasing the strain rate from 0.01 /s to 1 /s raises the absorbed energy from 0.53 j/cm3 to 1.72 j/cm3 while increasing the temperature reduces the absorbed energy due to the rise in loss modulus. it was also found that, irrespective of strain rate variation, the poisson’s ratio remains around 0.4 and decreases to negative values as the deformation exceeds the critical strain.