Nondestructive Assessments of Residual Stresses in Railroad Wheel Rim by Acoustoelasticity

Residual stress in the rim of railroad solid wheel was measured nondestructively by an acoustoelasticity method which makes use of the birefringent effect. The acoustic anisotropy is a fractional velocity difference of two shear waves polarized perpendicularly in principal directions and is proportional to the principle stress difference. However, in order to get the residual stress nondestructively, the contribution of texture anisotropy has to be separated from the total acoustic anisotropy. The scatter of the texture anisotropy was investigated using seven wrought wheels, four of which were used for drag brake tests that were to change the residual stress level. The initial and after braked residual stress was analyzed by acoustoelasticity, and the results were compared with the conventional methods and FEM analysis. Conclusively, it is expected through this study that the residual stress averaged through thickness in the rim can be assessed nondestructively by using the average value of the texture anisotropy in the rim within 40 MPa of difference compared with the estimation by conventional destructive methods.