Transverse Cracking and Stiffness Reduction in Cross Ply Laminates of Different Matrix Toughness

Abstract

Cross ply laminates of (02,902)s configuration 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.

Monitoring quasi-static and cyclic fatigue damage in fibre-reinforced plastics by Poisson’s ratio evolution

“…It is important to mention that the mechanical behaviour in the 11 e r and 22 e r direction is quasilinear until failure, as shown in Figure 1 and Figure 2. In this manuscript, only the [0°/90°] 2s sequence has been considered for studying the evolution of the Poisson's ratio, because a lot of researchers have proved that in case of transverse matrix cracking in the 90° plies, the Poisson's ratio ν xy should decrease [21][22][23][24][25][26].…”

Transverse cracks in cross-ply laminates. 1. Stress analysis

“…Experimental studies of brittle and tough polymer matrix composites with very similar elastic properties of plies show different cross-ply laminate stiffness reduction due to transverse cracking [7]. The reason may be deviations of the real crack shapes from the "ideal" ones due to local delamination and crack tip branching.…”

Constitutive relation and stiffness degradation of cracked anisotropic composite laminates(II) —determination of resolved stiffness and investigation of stiffness degradation for cracked laminates

“…The properties of materials used in the following analysis are taken from Reference [2]. For AS4/3501--6 laminates: Eti = 140.1GPa, Em = 8.36GPa, G12 = 4.31GPa, C~ = 3.2GPa, u~= 0.253, vz3 -0.297, the thickness of a single ply is 0.149ram.…”

“…For the constraint ply (2), all coupling stiffness elements in the matrixes are chosen to construct the stiffness matrixes for subproblem b. For the cracked ply (1), correspondingly, all moduli should' also be resolved as follows:…”