A coupled constitutive relation with impulse‐momentum for compressive impact behavior of the expanded polypropylene foam

In this article, the Jeong et al.'s constitutive relation and the impulse‐momentum theorem were coupled to characterize the compressive impact loading of EPP (Expanded polypropylene [EPP]) foams under varying strain rate conditions for each step. Simultaneous nonlinear Newton–Raphson method was applied to find the proper values for parameters in the constitutive relation along with quasistatic test data. Also, parameters which have physical meanings were expressed as functions of relative density. Moreover, coupling of the constitutive relation and the impulse‐momentum theorem provided transient velocities of the striker successfully. Dynamic stress‐strain curves from the analysis showed good agreement with data from instrumented impact tests and the potential to be applied to different material type polymeric foams. POLYM. ENG. SCI., 59:49–57, 2019. © 2018 Society of Plastics Engineers