Modeling of time-dependent behavior of deformation and transverse cracking in cross-ply laminates

A model is developed to predict the transverse crack density and strain response in a cross-ply laminate under monotonic, bilinear and constant loading. First, the strain response of the cross-ply laminate due to transverse cracking is presented based on the viscoelasticity theory and shear lag analysis. The transverse crack density is given as a function of both time and stress using a probabilistic failure concept. Secondly, monotonic tensile tests, bilinear tensile tests and constant load tests of cross-ply laminates are carried out to measure the strains and transverse crack density. A few parameters necessary for the probabilistic function are determined from the monotonic tensile tests at various stress rates. Finally, good agreement of strains and crack density in bilinear and constant load cases between experimental results and predictions verifies the validity of the present model.