  A new phenomenological technique for using constant amplitude loading data to
predict fatigue life from a variable amplitude strain history is presented. A
critical feature of this reversal-by-reversal model is that the damage
accumulation is inherently non-linear. The damage for a reversal in the
variable amplitude loading history is predicted by approximating that the
accumulated damage comes from a constant amplitude loading that has the strain
range of the particular variable amplitude reversal. A key feature of this
approach is that overloads at the beginning of the strain history have a more
substantial impact on the total lifetime than overloads applied toward the end
of the cycle life. This technique effectively incorporates the strain history
in the damage prediction and has the advantage over other methods in that there
are no fitting parameters that require substantial experimental data. The model
presented here is validated using experimental variable amplitude fatigue data
for three different metals.
