Experimental and numerical in-plane displacement fields for determine the J-integral on a PMMA cracked specimen

Contrary to J-integral values calculated from the 2D numerical model, calculated J-integrals [1] in the 3D numerical and 3D experimental cases are not very close with J-integral used in the literature. We can note a problem of structure which allows three-dimensional effects surrounding the crack tip to be seen. The aim of this paper is to determine the zone where the Jintegral formulation of the literature is sufficient to estimate the energy release rate (G) for the 3D cracked structure. For that, a numerical model based on the finite element method and an experimental setup are used. A grid method is adapted to experimentally determine the in-plane displacement fields around a crack tip in a Single-Edge-Notch (SEN) tensile polymer (PMMA) specimen. This indirect method composed of experimental in-plane displacement fields and of 2 theoretical formulations, allows the experimental J-integral on the free-surface to be determined and the results obtaining by the 3D numerical simulations to be confirmed