Characterization of R-curve behavior of translaminar crack growth in cross-ply composite laminates using digital image correlation

This paper presents experimental methods to estimate crack-tip field parameters and characterize R-curve behaviors of translaminar fracture in cross-ply composite laminates using digital image correlation. The investigated crack-tip field parameters include stress intensity factor, energy release rate and effective crack length. The nonlinear least-squares method and conservation integrals are used to determine these parameters from elastic far-field displacements, based on the homogeneous approximation of anisotropic solids for composite laminates. The sources of error of the two parameter-estimation methods are investigated. The results of the two methods show good consistency. Finally, the two-stage rising R-curves are obtained with acceptable accuracy.