A Method for Evaluating Fretting Wear Scars in Thin Steel Roping Wires Based on Confocal Imaging Profilometry

摘要

Fretting is considered one of the most important degradation phenomena inside steel wire ropes. This phenomenon causes the formation of wear scars on individual wires, which will decrease the cross-sectional area of the rope. Hence, also the fatigue life of the rope will be reduced. The aim of this work is to describe a method for characterizing wear scars in thin steel roping wires using confocal imaging profilometry. This objective is a challenge because not only the scars are formed on curved surfaces (cylinders), but the cylinders can present helical or double-helical shape induced during the manufacturing process of the ropes. Therefore, different surface morphology measurement techniques are briefly described. A methodology to measure wear scars in steel roping wires is then presented: a confocal imaging profiler was employed and algorithms were developed to treat the data points provided by the confocal profiler and calculate the characterization parameters. In this way, the quantitative assessment of wear scars in thin steel wires can be performed.