Measurement of dynamic large-strain deformation maps using an automated fine grid technique

Automatic analysis of the dynamic deformation of a fine grid ruled onto a s pecimen's surface has allowed whole-field measurement of both in-plane disp lacement components. A high-speed camera was used to capture images of impa cts at velocities of over 500 m/s. The Fourier transform method and phase u nwrapping were used to calculate planes of phase coordinates which deform w ith the specimen. An iterative search algorithm yields the displacements di rectly by searching for the shifted location of each set of phase coordinat es in the image of the deformed specimen. This paper describes the applicat ion of a previously proven analysis technique to dynamic deformation. Simpl e sample preparation and experimental operation make this technique ideal f or the dynamic regime. (C) 1999 Elsevier Science Ltd. All rights reserved.