Fretting Fatigue Model

"Fretting is a wear phenomenon that occurs between two mating surfaces: it is adhesive in nature, and vibration is its essential causative factor. Usually fretting is accompanied by corrosion. In general, fretting occurs between two tight fitting surfacesthat are subjected to a cyclic, relative motion of extremely small amplitude. Fretted regions are highly sensitive to fatigue cracking. Under fretting conditions fatigue cracks are nucleated at very low stresses. Nucleation of fatigue cracks in frettedregions depends mainly on the state of stress on the surface and particularly on the stresses superimposed on the cyclic stress. The time to nucleation of cracks can be significantly reduced as a result of fretting. Common sites for fretting are in jointsthat are bolted, keyed, pinned, press fitted, and riveted. These sites are common in the assembly of most air vehicles, ground vehicles, power plants, equipment, and machinery. All applications that have safety issues, maintenance issues, and service liferequirements will benefit from quantitative methods that provide the impact of fretting on the component's service.The multi-task objectives of the plan discussed in this proposal are:1) Integrate and implement the techniques of modified fretting fatigue predictive analytic models into structural integrity framework,2) Demonstrate integration for applications to present and future U.S. military weapons programs, commercial aviation, auto