Nonlinear fatigue life prediction model based on the theory of the S‐N fatigue damage envelope

A nonlinear model is proposed in light of the theory isodamage curves, to assess cumulative fatigue damage under multistage loading. The curves were developed through S-N envelope, by Pavlou. adopted functional form a commonly accepted general form. In present work, stress function for life exponent derived with aid curve only. model, no adjusting parameters are necessary estimation. prediction compared experimental results various alloys and existing models. comparison made C35, C45, Al-2024-T42, 15HM, A336 GR 5, A387 GR22 two-stage loading high-low low-high, Al 6082-T6