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A Comparative Analysis of Step Loading and Staircase Testing for Fatigue Strength Estimation of an Engine Component
  • Todd Thompson,
  • Jinqiang Liu,
  • Chao Hu
Todd Thompson
Deere & Company

Corresponding Author:[email protected]

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Jinqiang Liu
Iowa State University
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Chao Hu
Iowa State University
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Staircase testing is a standard method for evaluating the fatigue strength of components. However, staircase testing assumes a normal distribution, while components can display bimodal behavior due to flaws in material, or issues during the manufacturing process. Three unique step loading data sets on different production crankshafts provide evidence that step loading reliably identifies material or manufacturing issues, that lower a component’s fatigue strength. Staircase testing has an 87% or greater chance of overestimating the component’s fatigue strength, which in turn overestimates the component’s expected reliability. For example, a component with a 99.9% reliability, based on staircase testing would only have a 74% reliability based on step loading. If a component contains an undetectable manufacturing defect, staircase testing has a 99% chance of overestimating the component’s fatigue strength. Step loading reliably improves the estimation of a component’s fatigue strength distribution while providing insights into a component’s defect tolerance.
17 May 2022Submitted to Fatigue & Fracture of Engineering Materials & Structures
17 May 2022Submission Checks Completed
17 May 2022Assigned to Editor
20 May 2022Reviewer(s) Assigned
15 Jul 2022Review(s) Completed, Editorial Evaluation Pending
22 Aug 2022Editorial Decision: Revise Major
11 Oct 20221st Revision Received
11 Oct 2022Submission Checks Completed
11 Oct 2022Assigned to Editor
13 Oct 2022Reviewer(s) Assigned
28 Oct 2022Review(s) Completed, Editorial Evaluation Pending
03 Nov 2022Editorial Decision: Accept