How is the Kf term used in the WB fatigue module?
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In the WB fatigue module Release 10.0, Kf is simply used to adjust the calculated alternating stress value for the fatigue calculations. The allowable number of cycles for a particular loading condition is the determined by the adjusted alternating stress range and the specified S-N curve (stress range versus number of cycles). For example, assume that you have the following SN curve: N (number of cycles) Stress Range (ksi) 100 100 1000 50 10000 25 100000 10 If you are using Mises stress criteria, and the calculated alternating Von Mises stress range from the ANSYS simulation is 25 ksi and the specified Kt is 2.0, then an alternating Von Mises stress range of 50 ksi (2.0*25 = 50) is used to determine the allowable number of cycles (1000) for that loading condition. The specified Kt does not affect the calculated stress results (e.g., stress contour plots). It only affects the alternating stress difference range used in the fatigue calculations. |
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