From image analysis to damage constitutive law identification

Based on digital images of a tested sample, taken at different stages of loading, displacement fields are measured by using digital image correlation. The technique used here directly provides continuous displacement fields decomposed onto finite elements. From the latter, the equilibrium gap method allows one to estimate a scalar damage field over the same region of interest. Last, under the assumption of a unique constitutive law, the damage growth law is directly estimated from a series of displacement data. This procedure is illustrated on an experimental test case, namely a composite plate whose polymer matrix is reinforced with glass fibres, under equibiaxial tension loading.