Experimental investigation of 3-D crack-tip deformation using moire-Sagnacinterferometry

A combined moire-Sagnac interferometry method was applied for in;plane and out-of-plane crack-up surface deformation measurement. Based on 2-D and 3-D Jacobian derivative method (JDM), a stress intensity factor. evaluation pr ocedure is proposed This procedure utilizes selected measured displacements around the crack-up region as input nodal displacements to calculate the s tr ess intensity factor and the results correlate well with the theoretical calculations. The extent of the 3-D crack-tip deformation zone is also dis cussed.