Continuous out-of-plane deformation measurements of AA5083-H116 plates subjected to low-velocity impact loading

An optical system based on structured light and close-range photogrammetry has been developed and is in this study used to continuously measure the full-field out-of-plane deformation of aluminium plates subjected to low-velocity impact loading. During testing, square AA5083-H116 aluminium plates with thickness 5 mm were mounted in a circular frame and impacted by a 30 mm diameter blunt-nose projectile with velocities ranging from 7 to 11 m/s, while the out-of-plane deformations were measured at the opposite side. A fringe pattern was projected onto the rear target surface by a slide projector and the variation in the pattern during penetration was observed by a high-speed camera recording 10,000 images per second. The recorded images were subsequently computer processed to provide full-field topography information of the target surface during deformation. Degradation of measurement data due to impact induced vibration has been evaluated and reduced to a minimum by isolating the optical system from the mechanical experiment. The out-of-plane deformation measurements were compared to non-linear finite element simulations, and the agreement between experimental and predicted results was in general found to be good.