Transverse cracking and stiffness reduction in cross-ply laminates of different matrix toughness

ABSTRACT: Cross ply laminates of (02,90)sconfiguration having AS4 graphite fibers in three epoxy resins of different toughness: 3501-6, Tactix® 556 and Tactix® 695, have been tested to determine their transverse cracking behavior and the associated mechanical response under longitudinal tensile loading. The test data are analyzed using Talreja’s con-tinuum damage model [1-3]. The material constants needed in the model to predict the in-plane stiffness changes are determined. The measured Poisson’s ratio, which shows signifi-cant change, is compared with the prediction of the model. The constants for the three materials are found to increase with the increase in their fracture toughness. 1