Stochastic Materials Design of Fibrous Composite Laminates

Abstract

One of the major objectives of this paper is to offer a practical tool for materials design of unidirectional composite laminates under in-plane multi-axial load. Design-oriented failure criteria of composite materials are applied to construct the evaluation model of probabilistic safety based on the extended structural reliability theory. Typical failure criteria such as maximum stress, maximum strain and quadratic polynomial failure criteria are compared from the viewpoint of reliability-oriented materials design of composite materials. The new design diagram which shows the feasible region on in-plane strain space and corresponds to safety index or failure probability is also proposed. These stochastic failure envelope diagrams which are drawn in in-plane strain space enable one to evaluate the stochastic behavior of composite laminate with any lamination angle under multi-axial stress or strain condition. Numerical analysis for graphite/epoxy laminate of T300/5208 is shown for the comparative verification of failure criteria under the various combinations of multi-axial load conditions and lamination angles. The stochastic failure envelopes of T300/5208 are also described in in-plane strain space.