Numerical Prediction Method of the Strength Deterioration of Short Glass Fiber Reinforced Thermoplastics due to a Slight Amount of Inorganic Addition Agent

Abstract

The tensile strength of injection-molded short glass fiber reinforced themoplastics which have been pigmented with a slight amount of titanium dioxide (TiO₂) decreases. In this paper, on the basis of micromechanics, the strength deterioration of the unnotched composite and the load-displacement relation of the notched one were predicted. Damage developed in the composite was modeled as a fictitious crack with cohesive stress acting on the crack surface. The relationship between the cohesive stress and crack opening displacement, i. e., the tension-softening relation, was theoretically determined. The tensile strength of the unnotched composite was estimated using the maximum stress from the tension-softening relation. Characterizing the mechanical behavior of the damage developed at the notch tip as the tension-softening relation, the load-displacement curve was obtained. The predicted tensile strength and load-displacement curve were compared with experimental ones and good agreements were found between the predicted and experimental results.