THE COMPLIANCE METHOD FOR MEASUREMENT OF NEAR-SURFACE RESIDUAL-STRESSES - ANALYTICAL BACKGROUND

Introducing a thin cut from the surface of apart containing residual s tresses produces a change in strain on the surface. When the strains a re measured as a function of the depth of the cut, residual stresses n ear the surface can be estimated using the compliance method. In previ ous work, the unknown residual stress field was represented by a serie s of continuous polynomials. The present paper shows that for stress s tates with steep gradients, superior predictions are obtained by using ''overlapping piecewise functions'' to represent the stresses. The st ability of the method under the influence of random errors and a zero shift is demonstrated by numerical simulation.