Error and Uncertainty Analysis of Non-Uniform Residual Stress Evaluation by Using the Ring-Core Method

Like other mechanical methods used for the residual stress evaluation on a generic structural component, the Ring-Core Method (RCM) is potentially subjected to various error sources that in some particular experimental conditions can lead to significant errors and/or uncertainties on the computed residual stresses. The accuracy of the residual stresses computed by the RCM can be improved by a proper error analysis that allows the user to correct the systematic errors, as well as to evaluate the remaining stress uncertainty due to the random errors. Therefore, in order to give a contribution to the accuracy of the RCM, in the present work the list of the main error sources is presented and the effects of each source on the computed residual stresses, is examined in detail. Moreover, a systematic procedure for the residual stress uncertainty estimation is implemented. Finally, the application of the proposed procedure for the evaluation of the biaxial residual stresses field simulated by FEM on a simple steel plate, has allowed to detect the quantitative effects of the main error sources on the computed residual stresses, corroborating the usefulness of the procedure proposed for the correction of the systematic errors and the estimation of the uncertainty of the principal residual stress and their orientation.