Moire Fringe Method for Measuring Strain Profit Near the Luders Band Front : Case of Cross-Sectional Shear Yielding in a Twisted Thin Wall Tube

Abstract

The Moire fringe technique is presented as a method of measuring inhomogeneous distribution of small strain. The method was applied to the measurement of the plastic strain profile near the running Luders band front in twisted thin wall bars of mild steel. A fine Moire grid pattern was photo-printed on the curved surface of the bar. The material constants of the yield initiation condition in shear were obtained from the measured strain profiles.