GLS strength prediction of glass-fiber-reinforced polypropylene

The study discussed the strength of unidirectional (UD) discontinuous-fiber-reinforced composites, σ_UD, based on the global load-sharing (GLS) assumption. Two types of GLS approaches to predict the composite strength, were applied. The GLS model focuses on one fragmented fiber, aligned in the fiber axial direction , and neglects the interaction among fibers in the fiber cross-sectional direction. One approach is based on Monte Carlo simulation for fragmentation in a fiber composite, and the other is based on the analytical model by Duva et al. With these two models, the study calculated the stress-strain response until the fiber bundle stress dropped to 90% of the maximum attained stress. The results also predicted the strength of long discontinuous-fiber-reinforced composites, and also reported their applicability. The results also implies that the fracture mode of the discontinuous-fiber-reinforced composite changes from the matrix-cracking mode to the fiber-breaking mode when the aspect ratio for the fiber length to the fiber radius is sufficiently large.