Evaluation of impact-induced transient deformations using double-pulsed electronic speckle pattern interferometry and finite element

Transient out-of-plane displacements generated in a steel cantilever beam b y an impact load are measured using a double-pulsed electronic speckle patt ern interferometry system. The state of deformation of the object is freeze d using a ruby laser and the pulse emission is synchronised with the impact load. Correlation fringes for different times after the start of the impac t are obtained using a digital image system. For each time, transient displ acements are evaluated by digital analysis of the fringes. In order to test the experimental results, the time response of the beam subjected to the i mpact load is evaluated using a 3-D finite element analysis. A close agreem ent is found between the experimental and numerical results, which prove th e reliability of the optical technique to measure high-speed transient defo rmations. (C) 2000 Elsevier Science Ltd. All rights reserved.