A computer aided analysis method is described for durability assessment in the early design stages using multibody dynamic analysis, finite element stress analysis, and fatigue life prediction methods. From multibody dynamic analysis of a mechanical system, dynamic loads of a mechanical component were calculated. Finite element stress analysis with substructuring techniques produced accurate stress fields for the component. From the dynamic loads and the stress field of the component, a dynamic stress history at the critical location was produced using the superposition principle. Using Neuber’s rule, a local strain time history was produced from the dynamic stress history. The local strain based fatigue life prediction method was then used to predict “crack initiation” life of the critical component. The predicted fatigue crack initiation life was verified by experimental durability tests. This methodology can be combined with identification of weak links and optimization techniques such that the design optimization for an entire mechanical system based upon durability is possible during the early product development stage.

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