Residual Stress Measurement of Multi-Layered Plate by Strain Gauge Method

Abstract

The authors proposed a method to measure residual stress distributions in a multi-layered plate by utilizing strain gauge. The solution was derived from an integral equation of Volterra type in which strain to be measured were equated with those introduced with the axial force and bending moment by successive removal of thin layers. Formulas for a single plate and other special cases are derived from the general equation, and the former concides with the equation of Doi. It is noted that a multi-layered plate is constructed with materials of different linear expansion coefficients, so that the change of temperature in a test has some effect on residual stress distribution. The authors introduced a temperature compensating method for compensation coefficient upon measured strain. As applications of the theory, they measured residual stress distributions in 3-layered electrodeposited plates of copper-steel-copper and nickel-steel nickel. It has been confirmed that the residual stress distribution obtained by means of Strain Gauge Method is almost equal to that of Curvature Method, and the former is of sufficiently practical use.