Usinagem

Bending of helically twisted cables under variable bending stiffness due to internal friction, tensile force and cable curvature

Konstantin O. Papailiou

DISS

ETH

No. 11057

DISS

ETH

No. 11057

Bending of helically twisted cables under variable bending stiffness due to internal friction, tensile force and cable curvature
DISSERTATION
for obtaining the title of
DOKTOR DER TECHNISCHEN WISSENSCHAFTEN
[DOCTOR OF TECHNICAL SCIENCES] of the
EIDGENÖSSISCHE TECHNISCHE HOCHSCHULE ZURICH presented by

Konstantin O. Papailiou
Dipl. El.-Ing. TH Braunschweig
Dipl. Bau-Ing. Universität Stuttgart born on 3.7.1946 in Athens, Greece

Accepted on application by:

Prof. Dr. H.-R. Meyer-Piening, Supervisor
Prof. Dr. G. Oplatka, Co-Supervisor
Dr. V. Esslinger, Co-Supervisor
1995

For my father

Summary

The bending of helically twisted cable is a severe loading case for these important structural components. During bending of such cables, slippage takes place between the individual wires of the cable, which is greatly influenced by the frictional forces acting at the inter-wire contacts. Because of this slippage, the cross-sections of the cable do not necessarily remain plane, which has to be considered in the formulation of the bending stiffness of the cable.
The main subject of this work is to develop, based on generally accepted principles for bending of cables, an adequate model to quantify the bending behaviour of multilayered helically twisted cables.
This model leads, under consideration of internal friction, to a variable effective bending stiffness which depends on the cable curvature and the tensile load acting on the cable. With this information it is now possible to calculate the deflection, curvature and the various components of stress in the wires of the cable analytically. With the newly developed “cable scanner”, the catenary and curvature of the cable axis can be determined by scanning the cable