Fracture Problems in Composite Materials

In this paper a series of fracture problems in composite materials are identified, their methods of solution are briefly discussed, and some sample results are presented. The main problem of interest is the determination of the stress state in the neighborhood of localized imperfections such as cracks and inclusions which may exist in the composite. Particular emphasis is placed on the evaluation of quantities such as the stress intensity factors, the power of the stress singularity, and the strain energy release rate, which may be used directly or indirectly in connection with an appropriate fracture criterion for the prediction of fracture initiation and propagation load .levels. The topics discussed in the paper include a crack in layered composites, a crack terminating at and going through a bi-material interface, a penny-shaped crack in a filamentreinforced elastic matrix, and inclusion problems in bonded materials. The research reported in this work was supported by The National Science Foundation under Grant GK-11977 and by the National Aeronautics and Space Administration under Grant NGR-39-007-11O.