טכניון מכון טכנולוגי לישראל
הטכניון מכון טכנולוגי לישראל - בית הספר ללימודי מוסמכים  
Ph.D Thesis
Ph.D StudentAshkenazi Ronen
SubjectThe Mechanical Behavior and Fatigue Life of Wire Ropes
DepartmentDepartment of Mechanical Engineering
Supervisors Professor Menachem Weiss
Professor David Elata


Abstract

A new model to analyze the mechanical behavior of a wire rope is presented. The model fully considers the double helix configuration of the individual wire. The stiffness matrix of an un-lubricated axially loaded rope is simulated by means of a fiber and a material element kinematics that are applied on the wire centerline and on material elements respectively. By means of Love’s theory, the bending and torsion stress distributions along the double helix wire are simulated for axial loading under free and fixed ends conditions and bending over a sheave. The mechanical behavior of a rotating and a non-rotating rope was simulated and compared to new experimental data that was measured in a tension torsion machine.

The model is then combined with the two term fatigue model to predict the fatigue life of the individual wire when subjected to tension-bending fatigue loading. It is assumed that initial flaws that are generated during the cold drawing of the wire behave as initial cracks. The influences of the initial flaw size, the sheave arrangement, the ratio between sheave and rope diameters (D/d), sheave’s friction and the load on the fatigue life were studied. For the individual wires within the 18´7 non rotating rope, adequate agreement with respect to Feyrer’s empirical formula (1995) were obtained. Based on the simulations of some specific loading case studies, engineering recommendations were suggested. This model may be an efficient alternative for an expensive and complex experimental study.