Abstract
The use of mesh based global digital image correlation is proposed for measuring displacement fields around a crack tip and evaluating the fracture mechanics parameter, J-integral. The displacement gradients and the strains on the integration domain are determined from the measured displacement fields using a finite element smoothing technique. Then, the stresses are determined using the elastic-plastic constitutive relations with the strain incremental theory. J-integral values are then obtained by performing the numerical integration on the domain. The effectiveness is demonstrated by measuring the displacement fields around a crack of an aluminum specimen and evaluating J-integral. Results show that the near-tip displacement distributions are obtained accurately using mesh based digital image correlation with singular elements at the crack tip. Furthermore, the J-integral values can be obtained from the measured displacements by the proposed procedure.
