fatigue - COMBINATION OF LOADING MODES Suppose part is...

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COMBINATION OF LOADING MODES Suppose part is loaded in different modes: axial, bending, torsion. Then you may have nominal stresses (i.e., before any correction factors are used) From axial load: σ a axial m axial (nominal) From bending load: a bending m bending (nominal) From torsional load: τ a torsion m torsion (nominal) To estimate fatigue life: 1. Compute S n from using C n S L C S and C G , i.e., S n = C L C S C G n S 2. If present, apply stress concentration factors to both the K f axial , K f bending , K f torsion alternating and the nominal component of the stresses. Recall that K f = 1 + q ( K t 1) where q is the notch sensitivity and K t is the theoretical stress concentration factor (from static analysis). Also, apply the safety factor SF here. Thus nominal nominal () axial axial axial axial axial axial af a mf m SF K SF K σσ nominal nominal bending bending bending bending bending bending a m SF K SF K nominal nominal torsion
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This note was uploaded on 07/25/2008 for the course ME 471 taught by Professor Diaz during the Spring '06 term at Michigan State University.

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