A STATISTICAL-MODEL OF RESIDUAL STRENGTH AND FATIGUE LIFE OF COMPOSITE LAMINATES

A statistical model for the prediction of residual strength and fatigue life of composite laminates has been developed on the basis of the statistical nature of fatigue damage and the concept of a representative volume for damage evolution. The representative volume consists of a critical element which defines failure and residual strength and a subcritical element that describes stress distributions associated with progressive damage accumulation. The statistical equation of residual strength evolution is first established and the density distribution function of the residual strength is then derived from the static strength distribution. The residual strength and the fatigue life of composite laminates can be determined from the knowledge of these equations together with a stress redistribution factor which controls the global stiffness reduction. Comparisons of experimental data with theoretical predictions for glass/epoxy unidirectional and cross-plied laminates show good agreement, thus confirming the usefulness of the model.