Reply To: Strain vs. Stress Fatigue Analysis Result

[danielshaw]

Do the elastically calculated stresses exceed the material yield strength?  If so, then the SN results maybe suspect, and the EN results maybe more accurate.  However, often SN test data is more extensive and reliable than EN data for the same material, so the SN result might be based on superior test data.

Note:  SN and EN test data are developed using different test methodologies and the failure criteria are different, so I would not expect SN and EN to produce identical results. 4,500 vs 15,000 predicted cycles between them is not a signficant difference.