Compressive behavior and deformation mechanisms of rigid polymeric foams: A review

Polymeric foams have found their way into different industry sectors due to their excellent thermal and mechanical properties. Polymeric foams might undergo large deformation at high loading rates in their application in the transportation industry. Therefore, securing a proper understanding of their dynamic material characterization is essential for safe and optimum design. Significant research has focused on experimental investigations on the dynamic compressive behavior of polymeric foams using the Split Hopkinson Pressure Bar (SHPB) apparatuses. However, utilizing SHPBs to test foams is challenging. Droptowers, flywheels, pneumatic and hydraulic high-rate testing machines also have limitations in testing foams. Therefore, developing new/modifying current dynamic testing apparatuses for testing polymeric foams is still an open challenge. Anisotropy is one of the essential aspects of polymeric foams' mechanical behavior. Furthermore, polymeric foams exhibit different deformation mechanisms (and rate sensitivity) when loading in different material directions, resulting in challenges when assessing the dynamic anisotropic mechanical response. Analytical and phenomenological modeling approaches are computationally less expensive than Finite Element (FE) modeling in predicting foam mechanical response. However, FE modeling provides more accurate predictions. In addition, the capability of FE tools in simulating foam meso-structures has been increasing despite the existing challenges in simulating detailed foam meso-structures. This review paper critically discusses recent findings in meso- and macro-scale experimental, numerical, analytical and phenomenological investigations on the anisotropic dynamic mechanical behavior of polymeric foams. Furthermore, a detailed discussion of the specimen size effect on the polymeric foams’ rate sensitivity, considering the localization phenomenon, is presented within this manuscript.