Application of Moire Methods to the Determination of Transient Stress and Strain Distributions

When two arrays of lines are superimposed an optical phenomenon known as the moire effect is observed under certain conditions. This moire effect is used by the authors to determine the distribution of transient strains on the surface of two-dimensional bodies. The method can be used to solve completely the strain-distribution problem or it can be used in combination with photoelasticity to separate the principal stresses. The methods used in interpreting the moire fringe patterns and the techniques used to produce the patterns are described in the paper. Two applications are discussed.