Publication Abstract
Quantitative Uncertainty Analysis for a Mechanistic Multistage Fatigue Model
Xue, Y., Solanki, K.N., Steele, G., & Horstemeyer, M. (2007). Quantitative Uncertainty Analysis for a Mechanistic Multistage Fatigue Model . Proceedings of the 48th AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics, and Materials Conference, AIAA-2007-1982 . Honolulu, Hawaii.
Abstract
A quantitative approach is presented to evaluate the uncertainty of a microstructurebased
multistage fatigue (MSF) model for fatigue life predictions and fatigue damage
estimations. The microstructurally-based MSF model manifests the varying mechanisms of
fatigue damage incubation, microstructurally and physically small crack growth, and long
crack growth. The MSF model also incorporates the effects of microstructural features in
fatigue damage progression: 1) the size and morphology of discontinuities, such as
intermetallic particles and casting pores, 2) primary and secondary dendrites in cast alloys,
and 3) grain size and texture in wrought alloys. The MSF model lays a foundation to
evaluate the stochastic symbiosis of fatigue cracks with microstructural features that induce
large scatter in the fatigue life. The quantitative uncertainty analysis demonstrates
analytically the sensitivity of the MSF model parameters, random microstructural features
to the fatigue life and uncertainty propagation of each parameter with respect to the fatigue
life. The uncertainty magnification factor and uncertainty percentage contribution of each
model parameter are quantified to provide understanding of each parameter’s contribution
to the overall fatigue behavior. This paper demonstrates that a mechanistic multistage
fatigue model, with multiple parameters related directly to microstructural features, induces
less uncertainty in the results. The MSF model is a true high fidelity model that possesses
great potential in structural prognosis in various applications.