A micromechanically-based constitutive model for the elasto-viscoplastic deformationand texture evolution of semi-crystalline polymers is developed. The modelidealizes the microstructure to consist of an aggregate of two-phase layered compositeinclusions. A new framework for the composite inclusion model is formulatedto facilitate the use of finite deformation elasto-viscoplastic constitutive modelsfor each constituent phase. The crystalline lamellae are modeled as anisotropicelastic with plastic flow occurring via crystallographic slip. The amorphous phaseis modeled as isotropic elastic with plastic flow being a rate-dependent processwith strain hardening resulting from molecular orientation. The volume-averageddeformation and stress within the inclusions are related to the macroscopic fieldsby a hybrid interaction model. The uniaxial compression of initially isotropic highdensity polyethylene (HDPE) is taken as a case study. The ability of the modelto capture the elasto-plastic stress-strain behavior of HDPE during monotonic andcyclic loading, the evolution of anisotropy, and the effect of crystallinity on initialmodulus, yield stress, post-yield behavior and unloading-reloading cycles arepresented.
Dommelen, van, J. A. W., Parks, D. M., Boyce, M. C., Brekelmans, W. A. M., & Baaijens, F. P. T. (2003). Micromechanical modeling of the elasto-viscoplastic bahavior of semi-crystalline polymers. Journal of the Mechanics and Physics of Solids, 51(3), 519-541. https://doi.org/10.1016/S0022-5096(02)00063-7