On fretting maps

Experimental observations and theoretical analysis show that the contact conditions in fretting change with increasing displacement amplitude. Three different regimes of fretting are distinguished using dynamic tangential force and displacement measurements. The corresponding modes of surface damage can be identified from post-test metallographic examination. The three regimes are as follows. (1) Stick regime. Very limited surface damage by oxidation and wear. No fatigue crack formation observed (up to 106 cycles). Low damage fretting. (2) Mixed stick-slip regime. Wear and oxidation effects are small. Accelerated crack growth may result in strongly reduced fatigue life. Fretting fatigue. (3) Gross slip regime. Severe surface damage by wear, assisted by oxidation. Crack formation limited. Fretting wear. In addition, the limiting conditions at which wear mechanisms and wear rates become identical to those in unidirectional sliding must be considered. This case is referred to as the reciprocating sliding regime. In practical applications, it is important to determine the fretting regime resulting from a given set of experimental conditions. In the present paper the concept of “fretting maps” is introduced as a tool to be used in this determination. A fretting map is a diagram showing the relevant regimes in two variables, with regime boundaries representing critical values for the transition from one regime to another. Examples of fretting maps with variation of displacement amplitude, normal and tangential force and frequency of vibration are given. The advantage of fretting maps in analysing experimental fretting results is illustrated by a comparison with literature data.