Combined approach to damaged wire ropes life-time assessment based on NDT results and rope mechanics

Abstract

Principles of strength assessment and life-time prediction of deteriorated wire ropes based on magnetic NDT technique are presented. The measured loss of metallic cross-section area due to abrasion, corrosion etc. and local wire breaks are treated as input data for mechanical model of rope structure. The rope is interpreted as a system with two degrees of freedom that enables to calculate the strains and stresses in each wire when the rope is subjected to tension, torsion and bending. Stress safety factor is considered as a generalized parameter that specifies the rope degradation and may be used for predicting the instant lifetimes during the rope operating history. The rope discard criterion refers to residual life-time calculated with respect to minimal allowable strength factor. Examples of integrity analysis of mine hoisting rope and jib crane rope under tension-bending fatigue loading are demonstrated. The residual strength estimates give the rope inspector further information that helps to make a valid decision on testing policy. © 2011 Published under licence by IOP Publishing Ltd.