The fracture behavior of graphite/epoxy laminates

The results of uniaxial tensile tests conducted on a variety of graphite/epoxy laminates containing narrow rectangular slits and square or circular holes with various aspect ratios are discussed. The techniques used to study stable-crack or damage-zone growth—namely, birefringence coatings, COD gages, and microscopic observations are discussed. Initial and final-fracture modes are discussed as well as the effect of notch size and shape and laminate type on the fracture process. Characteristic lengths are calculated using the point, average and inherent flaw theories and comparisons with observations are discussed. Further, the effect of flaw geometry on stress states and deformations is assessed.Y. T. Yeow is associated with Allied Chemical Corporation, Morristown, NJ 07960; was formerly Research Associate, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061Paper was presented at 1977 SESA Spring Meeting held in Dallas, TX on May 15–20.