canadaboy
November 21st, 2008, 02:37 PM
I have seen 2 traditional types fatigue (S-n) diagrams. 1) Plots (ln Stress) vs. (ln cycles). 2) Plots (Stress) vs. (ln cycles). The obvious difference is whether the Stress scale is plotted with or without a logarithmic transformation.
My question is: Does the Inverse Power Law L(Stress) = 1 / (K*Stress^n) model both of the above fatigue scenarios? From some brief math, it appears that it models Case (1), but not Case (2).
Comments, corrections, or confirmations?
If I have a material design combination that I have cause to believe more closely follows Case (2), would I be better off using a user-defined transformation L = C1 * exp( C2*Stress )?
My question is: Does the Inverse Power Law L(Stress) = 1 / (K*Stress^n) model both of the above fatigue scenarios? From some brief math, it appears that it models Case (1), but not Case (2).
Comments, corrections, or confirmations?
If I have a material design combination that I have cause to believe more closely follows Case (2), would I be better off using a user-defined transformation L = C1 * exp( C2*Stress )?