Nakagawa, Y., Takahashi, S., Masaki, M., and Imao, R., "Study of Effects of Residual Stress on Natural Frequency of Motorcycle Brake Discs," SAE Int. J. Passeng. Cars - Mech. Syst. 7(4):1435-1445, 2014, doi:10.4271/2014-32-0053.
In brake squeal analyses using FE models, minimizing the discrepancies in vibration characteristics between the measurement and the simulation is a key issue for improving its reproducibility.The discrepancies are generally adjusted by the shape parameters and/or material properties applied to the model. However, the discrepancy cannot be easily adjusted, especially, for the vibration characteristic of the disc model of a motorcycle.One of the factors that give a large impact on this discrepancy is a thermal history of the disc. That thermal history includes the one experienced in manufacturing process.In this paper, we examine the effects of residual stress on the natural frequency of motorcycle discs. The residual stress on the disc surface was measured by X-ray stress measurement method. It was followed by an eigenvalue analysis. In this analysis, we developed a unique method in which the residual stress was substituted by thermal stress. Using this method, the discrepancy between measurement and calculation of the natural frequency was reduced from ±5.2% to ±1.3%. In further study on the relationship between stress distribution and natural frequency, we clarified that the gradient of residual stress in radial direction and the stress distribution in depth direction have a large dependency on natural frequency.The developed method made it possible to minimize the frequency discrepancies between measurement and calculation that were unable to be compensated by the adjustments using parameters of part shapes and properties of materials. The method significantly contributed to the improvement of the accuracy of brake squeal analyses.