Development of a model for the prediction of the fretting fatigue regimes
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P.D. Nicolaou Silver and Baryte Ores Mining Co., S.A., GR 10672, Athens, Greece (Received 10 August 2000; accepted 10 July 2001)
The parameters that govern the life of metallic materials under conditions of fretting fatigue may be divided into two broad categories. The first category concerns the material properties (e.g., yield strength, elastic modulus, and surface roughness) while the second concerns the externally imposed loading conditions and contact geometry. The two in-contact materials may either stick, slip, or stick-slip (i.e., there is a slip and a stick region on their interface) against each other. It has been shown that the fatigue life reduction is highest under partial slip. The objective of the present research effort is to develop a model that enables the prediction of the particular fretting fatigue regime (i.e., slip, stick, or mixed). The parameters that affect the fretting fatigue life of metallic components were identified and integrated into a model, which allows the prediction of the interfacial contact conditions. The model was first used to identify the sensitivity of the fretting fatigue regimes upon the materials and external, and geometrical parameters. Experimental results concerned with the fatigue life were plotted on the fretting maps; the fretting fatigue regimes indicated by the latter enabled the interpretation of the experimental data.
I. INTRODUCTION
Fretting is defined as the small amplitude oscillatory motion between two components that are in contact. When the relative movement is the consequence of a cyclic load, which is applied to one of the components, the process is then termed fretting fatigue. Fretting fatigue is a material damage process that involves the synergistic action of three discrete mechanisms: wear, corrosion, and fatigue. Any nominally clamped components that are subjected to transient variations or oscillatory loads are susceptible to fretting damage. Reports of fretting damage span a range of tribological systems as diverse as riveted lap joints, ball bearings, orthopedic implants, turbine blades, and steel ropes, among others.1–3 Fretting fatigue is a surface phenomenon. Unlike plain fatigue, where the formation phase of crack development is normally associated with the presence of some preexisting macroscopic discontinuities or free formation of a crack from some surface irregularity, fretting fatigue is essentially a process involving the interaction between two bodies. The role of fretting on the fatigue life is confined to the formation and growth of a crack to a length, which is comparable with the characteristic dimension of the contact; at this point the influence of the contact stress field itself is essentially diminished and 2716
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J. Mater. Res., Vol. 16, No. 9, Sep 2001 Downloaded: 18 Mar 2015
the crack might equally be one associated with plain fatigue. The fretting process itself is controlled by the bulk geometry of the contacting bodies, their surface finish, the physical and mechanical properties of t
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