Characterizing and modeling the pressure- and rate-dependent elastic-plastic-damage behavior of polypropylene-based polymers

Polymers in general exhibit pressure- and rate-dependent behavior. Modeling such behavior requires extensive, costly and time-consuming experimental work. Common simplifications may lead to severe inaccuracy when using the model for predicting the failure of structures. Here, we propose a viscoelastic-viscoplastic damage model for polypropylene-based polymers. Such a set of constitutive equations can be used to describe the response of polypropylene under various strain-rates and stress-triaxiality conditions. The model can also be applied to a broad range of thermoplastic polymers. The experimental campaign that is needed to identify every parameter of the model accurately is detailed. The proposed model was validated by performing 3-point bending tests at different loading speeds, where the load-displacement response of polypropylene beam up to failure was accurately predicted.