Experimental and Numerical Investigation of the Material Behavior of semi-crystalline Polyamide 6

In the current work, the tensile properties of semi-crystalline Polyamide 6 are experimentally investigated for varying degrees of crystallinity, temperatures, and loading rates. Based on the experimental results, a phenomenological constitutive framework at finite strains is derived in a thermodynamically consistent manner. To this end, a hyperelastic-plastic intermolecular resistance and viscous molecular network resistance are considered. Non-linear kinematic and isotropic hardening as well as nonlinear relaxation behavior are incorporated, to account for the experimentally observed behavior. It is evident that the mechanical behavior of semi-crystalline polymers exhibits complex dependencies on the degree of crystallinity and the temperature. To capture these experimental findings, both quantities serve as input parameters. A staggered parameter identification scheme is proposed to obtain a unique set of material parameters. Finally, the great capabilities of the proposed framework, to accurately predict the three-dimensional, visco-hyperelastic-plastic material response are demonstrated