An Elastothermoviscoplasticity Anisotropic Damage Model for Short Fiber Reinforced Polymer Composites

By using the internal state variable (ISV) theory (Horstemeyer and Bammann, 2010), we developed a finite deformation anisotropic and temperature dependent constitutive model to predict elastoviscoplasticity and progressive damage behavior of short fiber reinforced polymer (SFRP) composites. In this model, the SFRP is considered as a simple anisotropic equivalent medium (lamina), and the rate dependent plastic behavior of the SFRP is captured with the help of three physically-based ISVs. A second-order damage tensor is introduced to describe the anisotropic damage state of the SFRP and the tensorial damage evolution equations are used based on the damage mechanism of micro voids/cracks nucleation, growth and coalescence. The constitutive model developed herein arises employing standard postulates of continuum mechanics with the kinematics, thermodynamics, and kinetics being internally consistent. The developed model is then calibrated to a 35 wt% glass fiber reinforced polyamide 66 (PA66GF-35) for future numerical analyses.