Abstract: Dual-rotary fretting is successfully realized by changing the tilt angle of rotation axis based on a low-speed reciprocating rotary motor system and a high-precision six-dimensional forces/torques sensor, which combined with the torsional and rotational fretting modes. The dual-rotary fretting tests of 50 steel flat against AISI52100 steel ball are carried out under tilt angle of 10°and 40° and various angular displacement amplitudes from 0.125° to 2°. Kinetic analysis of the fretting running behaviors is performed in combination with microscopic examinations through optical microscopy, scanning electric microscopy, surface profilometer. The results show that the dual-rotary fretting can be truly simulated and is strongly dependent upon the tilt angle and the angular displacement amplitude. Friction force/angular displacement (Ft-θ) curves can be used to characterize the rotational fretting running behavior, the friction force/angular displacement curves of 50 steel exhibit three basic types of linear, elliptical and parallelogram. The running and damage behaviors of dual-rotary fretting are obviously different from simple fretting mode, which is dominated by torsional fretting or rotational fretting. In addition, the asymmetric wear scar is a typical characteristic of dual-rotary fretting .

Key words: Fretting damage, Fretting mode, Rotational fretting, Torsional fretting, Torsional-rotational dual fretting