Article ID Journal Published Year Pages File Type
780592 International Journal of Fatigue 2016 14 Pages PDF
Abstract

In the automotive sector, the cumulative damage calculation method generally applied is the Palmgren–Miner-Hypothesis with its modification according to Haibach (steeper slope of the SN-line after the knee-point) as a means of also including the damage by stress amplitudes below the knee-point. This approach results in the total damage sum of the spectrum Dspec. However, the resulting question is the value of the allowable damage sum Dal for the evaluation of Dspec ⩽ Dal. The only design code that considers the assessment of cast iron components under spectrum loading is the FKM-Guideline of the Cooperative Research Association for Mechanical Engineering (FKM, Frankfurt/Germany) for designing machine components. Here, the theoretical Palmgren–Miner-damage sum Dth = 1.0 is still suggested as the allowable damage sum Dal despite the fact that this damage sum renders unsafe calculated fatigue lives in about 90% of all published results.The results obtained with component-like notched specimens of modern high-strength cast iron alloys (Rm = 650–800 MPa) such as EN-GJS-500-7, SiboDur 700-10 and MADI (Machinable Austempered Ductile Iron), which were investigated under a standard Gaussian spectrum for chassis applications and also for a fuller injection pump spectrum, suggest the allowable damage sum Dal = 0.3 for fatigue life estimations of components manufactured with these materials can be proposed; i.e. the allowable fatigue life is about one third compared to calculations with the theoretical damage sum Dth = 1.0 that is still used.

Related Topics
Physical Sciences and Engineering Engineering Mechanical Engineering
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