NOTCHED STRENGTH OF FABRIC LAMINATES .2. EFFECT OF STACKING-SEQUENCE

The effect of stacking sequence on the tensile strength of notched and unnotched woven fabric (WF) composite laminates has been experimentally investigated. Comparison is made with unidirectional (UD) tape laminate results that are available in the literature. The fabric structure is a governing parameter in the failure mechanisms of WF composites. The failure mechanisms of WF composites, therefore, differ from UD tape composites. The notch sensitivities of different lay-ups are compared by using the characteristic dimensions d0 and a0 of the Whitney and Nuismer fracture model. The ratio of predicted notched strength to unnotched strength, (sigma(N))PRE/sigma(0), is used to study the effect of stacking sequence and d/W ratio on the notch sensitivity of the WF composites. Results are presented for unbalanced plain weave E-glass/epoxy composites of eight different lay-ups. The criteria for choosing the optimum stacking sequence are discussed.