SHEAR TESTING OF TEXTILE COMPOSITE-MATERIALS

A new in-plane shear-test methodology, developed for laminated composi te materials, was extended to textile composites. The methodology inco rporates two recently developed advances: a new specimen and a special strain gage. When used together, they produce accurate and consistent shear characterization of laminated and textile composite materials. The ''compact shear specimen'' incorporates many of the advantages of the similar Iosipescu shear specimen but has a larger test section. A special strain gage called the ''shear gage'' integrates the shear str ain across the entire test section of the specimen to obtain the avera ge shear strain, regardless of the shear-strain distribution in the te st section. The methodology was used to test both 2-D braided and 3-D woven textile composites. The entire shear stress-strain response, inc luding the shear modulus and shear strength, was measured for nine tex tile composite architectures. The variation in shear modulus and shear strength were low and were comparable to the variation of tensile and compressive modulus for the respective materials. Moire interferometr y, a full-field optical method, was used to validate the test methodol ogy. Enhanced X-rays were used to document the damage accumulated duri ng failure of the specimens.