Here some conceptual approaches are presented for evaluating questions of fatigue in various modes in which a mechanical component may experience dynamic loading. When stress peaks from all of the types of stress (i.e. bending, torsion, axial) align in-phase and at the same frequency, a method based on von-Mises stress is particularly useful. An example problem is solved for a component loaded in such a way. Equivalent midrange and alternating stresses are computed for this example, and the ASME Elliptic criterion is used to evaluate a fatigue factor of safety. When it is discovered that this factor of safety is less than 1 (implying a finite predicted life) the number of cycles expected before failure is estimated.
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This lecture was presented on February 16, 2018. All retainable rights are claimed by Michael Swanbom.
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