Filamentary Composite Laminates Subjected to Biaxial Stress Fields.

摘要

A study is presented in which four biaxial test specimens suitable for composite materials are evaluated -the off-axis coupon,the bulge plate,the tubular specimen and the crossbeam. Improved specimen design and data reduction techniques are presented for the off-axis coupon. Also, a novel technique for testing tubes without mechanical attachment is presented. Feasibility tests were conducted with both test methods,primarily on the Narmco 5505boron-epoxy system,both in laminate and unidirectional form. The biaxial data is presented and the results are discussed. The maximum strain,Hill and Tsai-Wu failure criteria are used to predict biaxial behavior of composite materials. Hypothetical design allowable interaction diagrams are presented and compared to the biaxial data. (Modified author abstract)