Modeling of strength and stiffness of short randomly oriented glass fiber-polypropylene composites

This study presents an approach toward better understanding of the mechanical behavior of short discontinuous randomly oriented fiber-reinforced composites. Due to their expanded use, the combination of polypropylene (PP) matrix and glass fibers (GFs) was chosen as an example of an injection-molded short fiber system to represent the complex class of materials. Based on the systematic evaluation of available mathematical models for the estimation of mechanical behavior, in addition to the analysis of microscopic observations, improved models for the prediction of composite stiffness and strength were developed. The models developed in this study, take into consideration several aspects that are found in a nonperfect composite, such as fiber length, preparation and orientation, fiber-matrix bonding, and processing conditions. The new models show a good description of the actual behavior, not only for the GF-PP system under consideration, but also for various other short-fiber polymer composites cited by the literature, such as carbon and natural fiber systems.