GLS strength prediction of glass-fiber-reinforced polypropylene

Excerpt

Discontinuous-glass-fiber-reinforced plastic (GFRP) composite material is widely used in industrial fields, mainly because glass fiber improves the strength and stiffness of polymer and because it is much less expensive than carbon fiber. It is thought that the use of long fiber is important in more efficiently improving the strength and stiffness of composites. In our previous study [1], we reported that the fracture mode of the discontinuous-fiber-reinforced composite changes from the matrix-cracking mode to the fiber-breaking mode (Fig. 1), when the aspect ratio for the fiber length to the fiber radius exceeds about 150. We also demonstrated that the strength is dramatically improved compared to the strength of the short fiber-reinforced composites and that the global load-sharing (GLS) model can roughly predict the strength (Fig. 2). Recently, Thomason [2, 3] produced the long discontinuous-fiber-reinforced composites where the aspect ratio was about 250 and reported the stiffness and strength of the composites. In this article, we applied the GLS model to his experiments and discuss the validity of our models.

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