Shear Testing of Textile Composite Materials

Abstract

A new in-plane shear-test methodology, developed for laminated composite materials, was extended to textile composites. The methodology incorporates 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 strain across the entire test section of the specimen to obtain the average shear strain, regardless of the shear-strain distribution in the test section. The methodology was used to test both 2-D braided and 3-D woven textile composites. The entire shear stress-strain response, including the shear modulus and shear strength, was measured for nine textile 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 interferometry, a full-field optical method, was used to validate the test methodology. Enhanced X-rays were used to document the damage accumulated during failure of the specimens.