Inadequate experimental characterization of strength and deformation behavior of unidirectional fiber composites under planar biaxial stresses has hindered the development of complete material models. Here the recent development of a cruciform specimen with unidirectional gage section is presented, suitable to test glass/epoxy under combined high transverse and longitudinal tensile loads. The experimental program developed comprises of six different biaxial tensile load ratios. The results show significant influence of longitudinal stress on transverse nonlinearity of a glass/epoxy. Failure loci and failure modes in biaxial tensile strain and stress domains are presented, indicating a reduction of transverse strength by high longitudinal loads.

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