Simultaneous in-and-out-of-plane displacement measurements using fringe projection and digital image correlation

The combination of fringe projection (FP) and two-dimensional digital image correlation (2D-DIC) has been proposed in previous work [1] as an alternative method to obtain displacement maps in the three spatial directions. However, if a telecentric lens is not employed in the experimental setup, the in-plane displacements obtained with 2D-DIC are influenced by the out-of-plane displacements occurring during deformation. Nevertheless, this error can be corrected if the out-of-plane displacements are known, for instance from measurements using the FP technique. In this paper a novel methodology based on the combination of FP and 2D-DIC is employed to perform the correction of the in-plane displacements, and is applied to several experimental examples. Results are compared and validated with those obtained using a commercial 3D-DIC system showing an average displacement error of 4% for X-displacements and 6.5% for Y-displacements.