if your stress cycles between some stress xMPa and 0? My fatigue limit is coming out smaller than my stress amplitude and consequently my component is falling outside of the bounded region. After looking a little closer, obviously the Goodman relation is still valid. So a subsequent question is: can I asume the fatigue (endurance) limit to be roughly half the ultimate tensile strength for steel? I think this may stop me getting the nonsensical answers my diagram is producing.