High speed photography of moire fringes. Application to ceramics under impact

A high speed moire photography system has been developed for measuring dynamic 2-D strain fields. The method is illustrated by an impact onto tiles of Silicon Carbide to display the history of the strain field. The steel blunt cylinder projectile is fired by a gas gun at a speed of 330 m/s. A checked,orating with 28 lines/mm was reproduced on the target lateral surface using aluminum. The moire fringes are recorded during impact by a high speed camera. Sequences of fringe patterns are analyzed by a 2-D Fourier Transform method to obtain the strain fields.