Use of the Moiré Effect to Measure Plastic Strains

Abstract

A method is described which should prove useful in the study of strain distribution in a metallic member during plastic deformation. Regularly spaced lines are drawn on a test specimen of interest and on a glass plate. After exposure to strain the part is photographed through the grid of lines on the glass. The strain distortion on the part results in an interference pattern from which the amount of plastic deformation may be calculated.