Wire Rope Roughness (WRR), a new indicator for the quantitative characterization of wire rope deterioration
While widely used for making retirement decisions, loss of metallic cross-sectional area (LMA) by itself is frequently not a good indicator of the actual wire rope condition. For example, wire fatigue breaks, single or in clusters, cause little or no LMA. Similarly, while corrosion pitting is associated with little loss of material, it is insidious because it damages the deep structure of the metal. To remedy this situation, this paper introduces the concept of Wire Rope Roughness
(WRR) as an additional quantitative indicator. WRR is defined as the aggregate roughness of all wires in a rope including broken wires and corrosion pitting. WRR is derived and extracted from the LMA signal in the following steps: Rope inspection and acquisition of a high-resolution LMA signal. Using the distance counter signal to produce a distance-based LMA signal. Removing measurement artefacts from the LMA signal by using the so-called echo cancellation (signal enhancement) algorithm to produce a high-fidelity LMA signal. Extracting a (high-fidelity) WRR signal from the high-fidelity LMA signal by a nonlinear, high-pass filter-like algorithm. Illustrated by examples, the paper describes the above steps in detail.
Author: H.R. Weischedel