Stochastic assessment of steel rope strength using magnetic NDT results

Technical Meeting Experiences with Ropes – Lenzburg 2003

The magnetic flux detector Intros detects two types of steel ropes damage: localized faults (LF) such as wire breaks and faults distributed along the rope length such as the loss of cross-sectional metallic area (LMA) (Mironenko & Sukhorukov, 1998). The measured characteristics of local and distributed defects are integral indexes of degradation. They do not account for the broken and missing wire distribution over the rope strands, wire layers in each strand and identical wire groups in every layer. Furthermore, both damage types have in general random locations. So the problem arises to develop a technique for degraded rope strength estimation, which is based on magnetic NDT results and makes use of a probabilistic approach. ln the absence of data concerning the mutual destructive action of LF and LMA on the rope's strength these two failure types will be considered separately. The combined effect may be estimated as a rough approximation by Superposition.

Author(s): V. Volokhovsky, A. Vorontsov, A. Kagan & V. Sukhorukov