Capturing Dynamic Behaviors of a Rate Sensitive, Elastomer with Strain Energy Absorptions and Dissipation Effects

A strain-rate-sensitive polyurethane elastomer is numerically investigated to reveal impact behaviors and analyze the inputted strain energy dissipation features with concerned rate dependencies. In view of the amorphous structure of elastomers, a thermo-mechanical model is developed via relating the macro-mechanical behaviors to micro-structural changes through molecular transitions and two distinct flow activations with each possessing a unique activation energy. Under large straining, detangling of molecular chains and networks through sliding is found to produce serious frictional effects resulting in instantaneous heat generation and temperature rise. To incorporate these heat-effected issues, an instantaneous temperature rise is calculated at each macro-level material point to ascertain the localized changes in the associated mechanical response. The overall perspectives of the dynamic mechanical behavior including visco-elastic large deformation, rate dependent yielding, thermal softening, flow at plateau stress, and strain hardening are found well captured. Investigations are extended for the material recoverability and accordingly, strain energy absorptions are clarified. Finally, a power law function is proposed for designing the energy absorption relation to the applied loading rate.