A REVIEW OF SPECIAL TECHNIQUES FOR MEASURING PLASTIC STRAIN

For simplicity, the techniques for measuring plastic strain are divided into two sections: (a) those which measure only surface strains and (b) those which are also capable of measuring internal strains. These latter techniques are of special interest and will be discussed in detail. The techniques in Section A will only be briefly dealt with for completeness as more detailed treatments are available elsewhere. Broadly the techniques fall into two categories: firstly, direct observations of the displacements associated with the strains, e.g., grids, moire fringes, and direct observations of dislocations, and secondly, indirect methods in which measurements are compared with a set of calibrated standards, e.g., etch pits, microhardness, and S-ray methods. (Author)