A STATISTICAL-THEORY OF THE TENSILE-STRENGTH OF SHORT-FIBER-REINFORCED COMPOSITES

This paper is concerned with the prediction of the tensile strength of short-fiber-reinforced composites by following the statistical theory of the strength of fiber bundles. Unidirectional, misaligned, and random-fiber directions are all treated. Depending on the fiber length, two failure modes can be distinguished. When the fiber length is smaller than 2L(c), where L(c) is the critical transfer length, the composite should fail by direct fiber pull-out. By contrast, it the fiber length is longer than 2L(c), most fibers break first and are then pulled out. At small fiber lengths, the prediction of the present theory is one-half the value predicted by the conventional model. However, the prediction of the present theory is in close agreement with that of the conventional approach if the fiber length is long.