Dual-motion fretting wear behaviour of 7075 aluminium alloy

The dual-motion fretting tests composed of the tangential and radial fretting, have been carried out. Such fretting mode is essentially induced by the action of an oscillating normal force in a ball-on-inclined flat contact (45° and 60°). Two flat specimens of 7075 aluminium alloy are symmetrically fixed at two sides of the 52100 steel ball in order to simplify dynamic analysis of the contact condition. The maximum imposed loads are varied from 200 to 800 N at a constant loading speed of 6 mm/min. Variations of vertical force vs. displacement have been recorded as a function of cycles. The effect of the cyclic vertical force and the inclined angle are investigated. Dynamic analysis in combination with microscopic examinations through optical microscopy and confocal laser scanning microscope (CLSM) shows that contact wear, cracking, and plastic deformation accumulation with a strong asymmetry in damage morphology occurred for dual-motion fretting. A transition of fretting mode from dual-motion to radial fretting mode may occur due to a strong modification of local contact configuration. Fretting behaviour between dual-motion, pure tangential and radial fretting is qualitatively compared.