Abstract:

Rotational fretting tests in a configuration of ball-on-flat were successfully realized by developing a new fretting device based on an ultra-low-speed reciprocating rotational driver. The rotational fretting tests of LZ50 steel flats against GCr15 steel balls were performed under different testing parameters. The results show that the rotational fretting behavior of the LZ50 is strongly dependent upon the angular displacement amplitude and the normal load. Friction force-angular displacement (Ft-θ) curves can be used to characterize the rotational fretting running behavior, which exhibits three basic types of the parallelogram, elliptical and linear cycles by varying the angular displacement amplitudes or the normal loads. The rotational fretting is characterized by elastic deformation coordination at the contact interface when run in the regime of partial slip. With the increase of the angular displacement amplitude and the decrease of normal load, the fretting running state transfers from the partial slip to the gross slip. The micro-examinations indicate that the plastic deformation, abrasive wear, oxidative wear and delamination are the main damage mechanism for LZ50 steel under the gross slip conditions. A special phenomenon which is different from that observed in the tests of the normal reciprocating fretting(tangential fretting), i.e. wear debris generated is accumulated in the centre zone of the wear scar under the condition of gross slip, is observed and analyzed herein.

Key words: fretting, rotational fretting, fretting wear, testing apparatus

摘要：

基于超低速往复转动电机和高精度六维力学传感器，研制了转动微动摩擦磨损试验装置，成功实现了球/平面接触条件下的转动微动；进行了GCr15钢球与LZ50钢在不同转动角位移幅值和法向载荷下的转动微动试验。结果表明：转动角位移幅值和法向载荷对转动微动行为有重要影响；可以通过摩擦力-转动角位移幅值（Ft-θ）曲线来表征转动微动行为，随着转动角位移幅值或法向载荷变化，Ft-θ曲线呈3种基本类型，即平行四边形状、椭圆状和直线状，分别对应于摩擦界面的完全滑移和部分滑移状态；LZ50钢转动微动在部分滑移状态下表现为弹性变形协调，损伤轻微；随着角位移幅值的增大或法向载荷的减小，微动运行于完全滑移状态，损伤表现为塑性流动、氧化磨损和剥层，其磨痕轮廓明显不同于切向微动模式。

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关键词: 微动；转动微动；微动磨损；试验装置