A non-linear damage model for the tensile behavior of an injection molded short E-glass fiber reinforced polyamide-6,6

Tensile experiments conducted on an injection molded short E-glass fiber reinforced polyamide-6,6 composite show that flow-induced fiber orientation due to injection molding caused higher tensile properties in the direction of flow compared to normal to the direction of flow. The presence of weld line reduced the modulus, tensile strength and failure strain of the material. Both elastic modulus and tensile strength of the material increased with increasing strain rate, indicating that this composite was a strain rate dependent material. Based on the experimental results, a nonlinear damage model was established to describe the stress-strain relationship of the short fiber reinforced polyamide-6,6. The parameters in this model are tensile modulus E, Weibull scale parameter σ0 and Weibull shape parameter β. It is shown that the Weibull shape parameter, β, does not depend on strain rate, and can be regarded a constant; however, the Weibull scale parameter, σ0, is a linear function of log (strain rate).