جستجوی مقالات مرتبط با کلیدواژه "ring-core" در نشریات گروه "مکانیک"

The aim of this paper is to compare incremental and integral techniques in non-uniform residual stress measurement by the ring-core method and to present a procedure to determine the calibration coefficients of the integral technique. The mathematical basis of the integral technique for use in the ring-core method is explained. To determine the calibration coefficients of the integral technique a 3D FE model was introduced and the calibration coefficients are also presented in separate tables. The FE analysis of the pure bending and ring-core method were used to show the effectiveness of the presented coefficients and compare the integral and incremental techniques. The results indicated that the calculated non-uniform residual stresses by the integral technique were closer to the real values in comparison with the incremental method. Moreover, it was observed that the accuracy of the results decreased by increasing the depth of the groove.

In this study, the calibration constants of incremental step method have been determined by finite element analysis to calculate the residual stresses by the ring-core method. The calibration coefficients have been determined by simulation the uniaxial and biaxial loading. It is indicated that the loading approach has not effect on the calibration constants and they are unique. The uniaxial condition has been used to determine the calibration coefficients in the experimental method. To verify the determined constants, the calibration factors have been used to calculate the residual stresses in the case of uniform and non-uniform residual stresses. The axial and biaxial conditions have been studied and the results are in good accordance with applied stresses in simulations. In the uniaxial loading the measured residual stresses in finite element model completely accommodated by the applied stresses and presented formula and calibration constants determined the direction of the maximum principal stress by clearance less than 0.7%. Clearance of the measures stresses and applied stresses in the non-uniform case was about 1 %. An experimental test has been used to show the effectiveness of the obtained calibration coefficient by finite element analysis. Also, it is indicated that the results of the experimental test are satisfactory.

The measurement of residual stress in rail foot, according to manufacturing standards is mandatory. In this study, the ring-core method and the sectioning technique are used to measure the residual stresses. A calibration technique for the ring-core method has been explained and simulated by the finite element analysis. The calibration coefficient has been determined for certain parameters and various depths of the annular groove. The ring-core method has been simulated for the uniaxial residual stress field and it is observed that the maximum error in the maximum principal residual stress was about 13% which is about 5% of material yield stress. The residual stresses have been measured at the UIC 60 rail foot by the ring-core method and the sectioning technique, and the results are in a good agreement with earlier investigations in this field. Also, it has been indicated that maximum residual stresses on the rail foot are not in the longitudinal direction and in the subsurface of the rail foot, the maximum principal direction coincides with the longitudinal direction. Both methods indicated tensile residual stresses on the rail foot, but the ring-core method predicted 27% higher longitudinal residual stress on the rail foot in comparing with the sectioning technique.