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Residual stress measurement is one of the most interesting research areas in experimental mechanics. Residual stress is introduced to material due to plastic deformation of parts and can be one of the most effective parameters on design and operation of parts. ASTM E837-01 standard studies residual stress determination in parts by hole drilling method and represent calibration coefficients for flat sheets with constant stress profile. However, there is no certain standard on the residual stress measurement by Incremental Hole Drilling Method (IHDM) which is the subject of this study. IHDM can obtain stress profile by using two modified stress calibration coefficients. In this article, the stress calibration coefficients have been extracted for incremental hole drilling by using finite element analysis (FEA). FEA contains both biaxial tension test and pure shear test which a hole has been drilled step by step in the parts by removing elements and the strains changes were determined at three strain gauge positions on the surface. At last, the calibration coefficients are determined for each step and the accuracy of coefficients have been verified by a set of experimental test and a FE analysis. The experimental test contains four-point bending of an AA5056 flat aluminum sheet. The numerical analysis contains four-point bending of a flat sheet. In both cases, the stress profile can be determined easily by using analytical equations. Average analytical stress in each increment has been calculated and compared with the result of numerical incremental hole drilling method. The comparisons show that numerical and experimental results have no significant differences in first six steps but in the last four steps show an increasing errors due to the change in stress profile and hole geometry. Results presents that the calibration coefficients have suitable accuracy in stress profile determination.

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In the present paper, the parameters of Johnson - Cook (JC) constitutive model for two steels have been identified, based on the Hopkinson pressure bar test results. The experimental data has been taken from the split Hopkinson pressure bar data found in the literature. Using the measured strain pulses, the experimental stress - strain and deformation - time curves can be extracted. The experimental data have been processed using two different methods. In the first method strain rate assume to be constant during deformation and in the other one the deformation has been applied to a modeled specimen. In each method, an optimal set of material constants for JC constitutive model have been computed by minimizing the standard deviation of the numerically obtained stress - strain curve from the experimental data. Also a sensitivity analysis has been performed on JC constitutive model parameters and temperature changes during test have been investigated. The obtained results show that using constant strain rate method, leads to considerable error in results; for example in this study the minimum error is about 14%.