@ARTICLE{Ghasemi, author = {Ghasemi, A. and AmirAhmadi, S. and Asgari, B. and Sareban, M.R. and }, title = {Calculating residual stresses by measured released strains using different linear and nonlinear approximations}, volume = {19}, number = {3}, abstract ={In this study, the method of releasing strains for calculating residual stresses in hole drilling process has been considered. For this purpose, a thick piece of cylindrical aluminum of 5 mm thickness has been investigated. Stepwise and high-speed drilling was performed in several successive steps, and released strains were recorded by a rosette strain gauge. The distribution of released strains in 3 forms of functions in the depth of the hole has been studied to transform strains to stresses, a linear function, a second-order function, and a third-order function. For each case, the longitudinal, tangential, shear stresses, principle stresses, and principle angles in the thickness of the piece were calculated and the results of the convergence analysis by the Tikhonov regularization were evaluated. In the end, the results are evaluated and compared for 3 modes. The results of the comparison of stresses and the degree of curves have shown that the third-order curve is more suitable for evaluation of released strains and using to transform them to residual stresses, and the magnitude of the error in the second-order curve is greater than the two other modes. }, URL = {http://mme.modares.ac.ir/article-15-18500-en.html}, eprint = {http://mme.modares.ac.ir/article-15-18500-en.pdf}, journal = {Modares Mechanical Engineering}, doi = {}, year = {2019} }