Random vibration fatigue - Steinberg 3 bands method
I'm doing a random vibration analysis and using Steinberg 3 bands method to evaluate fatigue life of structures. Steinberg method uses 1-sigma, 2-sigma, 3-sigma von Mises stresses and S-N curve to find fatigue life of structures. But in my case, only 1-sigma, 2-sigma stresses are located in high cycle zone of S-N curve. 3-sigma stress is very high and exceeds ultimate strength of material. Could any one tell me how to work around in this case? Thanks!