FAILURE PREDICTION OF FIBER-REINFORCED LAMINATES UNDER HYGROTHERMAL AND MECHANICAL INPLANE LOADS

A theoretical investigation using the failure tensor polynomial criterion was carried out to study the effect of off-diagonal failure tensor components on the limit behavior of symmetric fiber reinforced laminates under both mechanical and hygrothermal loading. In spite of obvious similarities in the mathematical expression of numerous failure criteria based on the tensor polynomial theory, their predictions may be substantially different depending on loading conditions and on the choice of stress-interaction terms. Although these predictions for unidirectional fiber reinforced laminae under biaxial loading do not exhibit remarkable differences, this is not the case for multidirectional laminates. Comparison of theoretical predictions with experimental data from in-plane loaded cross-ply Graphite/Epoxy laminates proved the reliability of the so-called generalized elliptic paraboloid failure surface criterion, assuming the existence of a safe triaxial loading path which may depend on the anisotropy of the medium and its suitability for use in structural design applications. (C) 1993 John Wiley & Sons, Inc.