Development of a test device for the evaluation of fretting in point contact

Abstract

AbstractFretting wear and fatigue may occur between any two contacting surfaces, wherever short‐amplitude reciprocating sliding is present for a large number of cycles. A test device has been developed for the evaluation of fretting fatigue and wear in partial and gross slip conditions. Three similar sphere‐on‐plane contacts run at the same time. Normal force, tangential force or displacement amplitude and constant bulk stress can be controlled and measured separately. Reciprocating tangential displacement is produced with rotational motion, the amplitude and frequency of which can be adjusted and controlled accurately by an electric shaker. The number of load cycles for crack initiation and growth is determined with strain‐gauge measurements near the fretting point of contact. The contact surfaces are measured with 3D optical profilometer before fretting measurements to determine actual contact geometry.The measurements were done with quenched and tempered steel. The initial results indicate that cracks are mostly formed in partial slip conditions, whereas fretting wear is more heavily involved in gross slip conditions. The initiation of a crack occurs near the edge of the contact in the slip direction, where the calculated cracking risk has its maximum value in partial slip conditions. The number of cracks increases as the displacement amplitude, i.e. friction force, increases in partial slip conditions. Copyright © 2008 John Wiley & Sons, Ltd.