DEVELOPMENT OF STRENGTH THEORIES FOR RANDOM FIBER COMPOSITES

A reassessment of existing theories for calculating the strength of random and quasi-random fiber composites is presented. Fundamental aspects regarding the physical model, macromechanics analysis, fiber distribution functions, generalized failure criterion, and progressive versus sudden failure models are covered first. Progressive ductile failure, progressive brittle failure, and sudden brittle failure are treated in detail. In each case, the original theory is briefly reviewed, and then its extensions accompanied by numerical examples are presented. Several limitations originally imposed by Hahn, such as the monotonically nonincreasing requirement on the failure strain curve, are lifted and the mathematical formulations are generalized. Some common misconceptions are also highlighted and clarified. Comparison with experimental data is given for the SMC-R50 material system. Good reproduction of the experimental results and of the stress-strain response are illustrated. A review of the main points and opportunities for further work are presented in conclusion.