EFFECTS OF FIBER LENGTH AND FIBER ORIENTATION DISTRIBUTIONS ON THE TENSILE-STRENGTH OF SHORT-FIBER-REINFORCED POLYMERS

This paper presents an analytical method considering the effects of fi ber length and fiber orientation distributions for predicting the tens ile strength (TS) of short-fiber-reinforced polymers (SFRP). Two proba bility density functions are used for modelling the distributions of f iber length and fiber orientation. The strength of SFRP is derived as a function of fiber length and fiber orientation distribution taking i nto account the dependences of the ultimate fiber strength and the cri tical fiber length on the inclination angle and the effect of inclinat ion angle on the bridging stress of oblique fibers. Then the effects o f the mean fiber length, the most probable length (mode length), the c ritical fiber length, the mean fiber orientation, the most probable fi ber orientation and the fiber orientation coefficient on the tensile s trength of SFRP have been studied in detail. This model provides the n ecessary information to determine what fiber length distribution, what fiber orientation distribution and what interfacial adhesion are requ ired to achieve a desired composite strength. The present theory is th en applied to existing experimental results and the agreement is found to be satisfactory. (C) 1996 Elsevier Science Limited