Measured strains correction for eccentric holes in the determination of non-uniform residual stresses by the hole drilling strain gauge method

Abstract

The hole drilling strain gauge method is one of the most used techniques to determine residual stresses. The presence of eccentricity between the centre of the hole and its theoretical position can compromise the accuracy of the method. The present work proposes a method to correct the measured strains in eccentric holes in case of non-uniform residual stresses. Depths where the strains are measured in the ASTM E837-13 are taken as a reference and specific functions are proposed to use the method without the need of performance finite element model simulations in each new problem. As a result, in contrast to previous works, any method to decode residual stresses can be applied directly and the correction method works very well for a wide range of common materials and hole diameters in the application of HDM. Numerical calculations verify the suitability of the proposed correction method for different eccentricity values and materials and show an accuracy of a few tenths of a percent. Working in this way, a test does not necessarily have to be discarded if its eccentricity is higher than the limit indicated by the Standard.