Fracture toughness of a composite reinforced with bone-shaped short fibers

Low fracture toughness has been one of the major drawbacks of short-fiber c omposites, which is caused mostly by the fiber-matrix interface. A strong i nterface is required for effective load transfer from the matrix to the fib er. However, a strong interface makes it difficult to relieve the fiber str ess concentration in front of an approaching crack, thus resulting in low f racture toughness. On the other hand, a weak interface will lead to an easy fiber pull-out, making the short fibers ineffective in bridging and arrest ing a propagating crack. We have recently found that bone-shaped-short (BSS ) fibers can effectively bridge cracks and increase fracture toughness by t ransferring load through the enlarged fiber ends while having a weak interf ace. In this paper, we present our results from both experiments and comput ational modeling to show the advantages of BSS fibers in improving the frac ture toughness. (C) 2001 Elsevier Science B.V. All rights reserved.