Out-of-plane deformation measurements of an aluminium plate during quasi-static perforation using structured light and close-range photogrammetry

An optical system using structured light and close-range photogrammetry for full-field continuous measurements of the out-of-plane deformation of a metal plate loaded at its centre by a moving punch is presented. The system is applicable both for quasi-static and dynamic loading conditions, but in this paper focus will be on the former. In the tests, a square AA5083-H116 aluminium plate is mounted in a circular frame and penetrated from above by a cylindrical punch, while the out-of-plane deformation is observed from below. A fringe pattern is projected on the target plate surface and recorded by a camera (or more than one if required). The changing fringe positions on the plate surface during perforation are then computer processed to give topography information of the out-of-plane deformation. This paper is divided into three major parts. First, the optical technique is presented with a description of the applied method, image analysis procedures, calibration of the system and estimation of accuracy of the acquired data points. The experimental set-up is then presented, and some results from a typical test where a 5 mm thick plate with free-span diameter of 500 mm is perforated by a 20 mm diameter blunt-nose punch are given. Finally, numerical simulations of the perforation process are carried out using the non-linear finite element code LS-DYNA. The numerical predictions are compared with the experimental observations and the applicability of the experimental method is discussed based on the obtained results.