Monotonic and cyclic short beam shear response of 3D woven composites

Monotonic multi-step and cyclic short beam shear tests were conducted on 20 and 3D woven composites The test results were used to determine the effect of z-yarns on the inter-laminar shear strength as well as the multi loading behavior The presence of z yarns was found to affect not only the inter-laminar shear strength of the composite but also the behavior of the composite beyond the elastic limit Microscopic examination of the damaged specimens revealed large delamination cracks in 2D woven composites while delamination cracks were hindered by z-yarns in 3D composites This crack arrest phenomena resulted in a reduction in inter-laminar crack lengths and a higher distribution of the micro-cracks throughout the 3D composite The multi-step and cyclic loading tests are found to be useful in the monitoring of specimen behavior during short beam shear testing The induced damage was quantified in terms of the loss of strength and stiffness during each loading cycle It was found that while the 2D composites have higher damage resistance the 3D composites have a higher damage tolerance (C) 2010 Elsevier Ltd All rights reserved