Uncertainty of residual stresses analysis in slitting method: A case study of roll bending process

Abstract

Slitting method or crack compliance method is used widely for residual stress measurement in different geometries, materials and processes. In this article, roll bending process is selected as a case study which can create residual stress in manufactured parts. The slitting method is employed to determine the residual stresses in a roll-bent stainless steel 314 sample. The series expansion approach is used for residual stress calculation. The compliance matrix is determined by finite element analysis. The uncertainty analysis and average strain misfit are used as two criteria for selecting the best order of expansion. The results show that nine terms of Legendre basis function (L₂–L₁₀) can calculate residual stress profile accurately. It is observed that a maximum of 117 MPa residual stress magnitude is induced to the sample. The sample was manufactured with 1.078 m curvature radius by three-roll bending process. The sample thickness was 10 mm. The average uncertainty for residual stress distribution through the slit is equal to 3.6 MPa, while the maximum value of uncertainty could be estimated to be about 21 MPa. The analytical residual stress is also calculated by assuming power law material behavior and compared with the experimental results. This comparison shows a good agreement between the experimental and analytical solution.