Quantitative Failure Analysis Using a Simple Finite Element Approach
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Failure analysis encompasses the examination of a failed component and assessment of the failure situation in order to determine the causes of failure. Metallurgical and manufacturing defects often initiate a crack that subsequently propagates under service conditions, leading to premature failure and/or catastrophic fracture of the component. Traditional failure analysis performed on failed section often constitutes only of qualitative metallurgical and microstructure studies in establishing the causes of failure. Since the failed parts have likely been subjected to tensile overload, localized fatigue damage and/or excessive creep strains, the mechanics aspects of the failure should also be considered in the failure analysis. This includes load and stress analyses, fatigue life calculations, and failure simulations. In this respect, finite element (FE) analysis offers a simple, yet effective approach in establishing the causes of failure by predicting the internal states of strains and stresses in the material relative to the strength of the material during the fracture event. Qualitative metallurgical and fractographic results complement such FE-based prediction of the failure.
KeywordsQuantitative failure analysis Finite element analysis Fatigue Decarburization
The coil spring samples used in this paper were provided by Nasco, Bowling Green, KY, USA. The fatigue tests were all performed by the experimental team at NHK International, MI, USA.