In-plane wavefield detection in lattice structures via digital image correlation

Abstract

We describe an experimental procedure to measure in-plane waves in an hexagonal lattice structure through digital image correlation. Measurement are performed by exciting the structure with a narrowband signal, then recording the evolution of the wavefield by using a single high-speed camera pointed at the lattice. By tracking the position of the lattice intersections, we are able to obtain the time evolution of the interpolated in-plane displacement field, which we use to separate the longitudinal and shear components of motion through Helmholtz decomposition. The proposed approach allows us to investigate the dispersion characteristics of P- and S-modes. For each of these two modes, we focus on the directionality of wave propagation by obtaining experimental dispersion surfaces, which are in excellent agreement with the theoretical ones. We also compare the RMS plots of the experimental displacement field to the components of the group velocity vector for the P and the S -modes computed theoretically, s...