Hee-Jin Shim*, Jung-Kyu Kim
The Journal of Mechanical Science and Technology, vol. 25, no. 3, pp.621-629, 2011

Abstract : For the reliability of automotive components, it has to satisfy the dimension accuracy and the strength design requirements for part that has the consistent strength distribution. Since it has the defect due to actual manufacturing process and inhomogeneity of material, the strength design requirement should be not satisfied. In this way, verification of analysis and prediction of fatigue life was very difficult from difference of the failure region. The cold forging products generally has heterogeneity of strength, hardening and fatigue resistance. Therefore, it’s important to understand the characteristics of material strength and fatigue of cold forging products considering heterogeneous effect in order to do durability analysis. In this study, in order to propose the method of durability analysis with inhomogeneity of the material, the heterogeneous characteristics are confirmed by predicting the effective strain to perform the plastic deformation simulation influenced from the strength condition and microstructure of pulley at power transmission. Analysis and prediction of effective strain from cold forging is performed by software DEFROM for inhomogeneous characteristics. And the stress of the real operation in performed by MSC.NASTRAN. Also, through correlation about effective strain and hardness, the failure position and the life were estimated to predict the fatigue strength and the external applied stress.

Keyword : Cold forging; Fatigue life evaluation; Effective strain; Inhomogeneous properties