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The multitask objectives of the plan discussed in this proposal are to research the role and effects of fretting on structural life of components; develop and demonstrate the feasibility of integrating candidate fretting fatigue predictive analytic model(s) into structural integrity methods; integrate and implement the techniques for applications to present and future U.S. military weapons programs, commercial aviation, automotive, and mechanical equipment; and provide industry access to the predictive tools and information for commercialization.

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A fracture mechanics-based approach which uses Mode I Stress Intensity Factor (SIFs) to estimate the influence of fretting fatigue loads (which can consist of normal and shear contact loads, as well as bulk or far-field loads) has been proposed by Rooke and Jones (“Stress Intensity Factors in Fretting Fatigue,” Journal of Strain Analysis, Vol. 14, No. 1, 1979, pp. 1–6), who proposed a cracking scenario in which a single edge crack propagates to failure under the influence of the contact and bulk stress damage drivers. A major shortcoming of this approach is that the underlying analytical method and closed form integral equations assume that the single edge crack propagates into a semi-infinite domain or half-space. Significant differences in the stress states for finite width domains have been postulated by Fellows et al. (“Contact Stresses in a Moderately Then Strip (with Particular Reference to Fretting Experiments,” Wear, Vol. 185, 1995, pp. 235–238) among others. SIFs can be roughly correlated with stress; therefore variations in the stress states normally result in variations in the SIFs. Variations in the SIFs due to shear and normal contact loads, and due to finite width effects are quantitatively evaluated with the finite element method (FEM). Results with the finite element approach are compared to those using the Rooke and Jones method, as well as other results from the open literature.