Digital speckle shearography setup to measure the field-induced strain map in piezoelectric materials

Residual or induced strains are important factors in the performance of electronic devices, actuators, and sensors. In this paper, we report the application of digital speckle shearography to obtain the two-dimensional field-induced out-of-plane strain maps in a piezoelectric slab under a varying electric field. Both the free-standing and loaded (pinned) states are investigated. The results show field-dependent strain maps with parabolic profiles on the order of 10^-4 and 10^-3 in the free-standing and pinned states, respectively, in agreement with typical values for piezoelectric ceramics. This study provides a simple, non-destructive, and full-field method to characterize these materials.