The Effect of Ply Lay-Up Sequence on the Fracture Toughness of Boron Aluminum

Abstract

The fracture toughness of 0/90° cross ply boron reinforced aluminum composites has been investigated using prenotched compact tension and center notched tensile specimens. The effects on fracture toughness of specimen geometry, the relative numbers of 0° and 90° plys, and the lay-up sequence, have been measured. Ply lay-up sequence has been shown to affect fracture morphology and in turn alter the value of toughness. This has been related to the degree of matrix deformation which can take place to blunt the advancing crack. The relative numbers of 0° and 90° plys has been shown to be the major controlling factor and simple calculations based on a rule of mixtures approach provide reasonable agreement with the experimental data.