Predictions of static and dynamic performance of multi-layered spiral strands under various loading conditions.
The upper bound to the frictional damping of axially preloaded single
layer strands subjected to cyclic bending to a constant radius of curvature
has been determined. The theoretical model includes a modified
frictional approach which takes no-slip to full-slip friction transition over
the individual interwire contact patches into account. Numerical results
show that cable damping may be increased by increasing the number of
wires and/or increasing the lay angle.
Using the orthotropic sheet concept, and employing established results
regarding the frictional contact of non-spherical bodies, an analytical
model has been proposed for estimating the bending stiffness and
hysteresis of axially preloaded multi-layered spiral strands undergoing
uniform cyclic bending movements. Also investigated are the bending
characteristics of axially preloaded sheathed spiral strands experiencing
high external hydrostatic pressures such as those in deep water platfonn
applications. Based on a series of theoretical parametric studies on a
number of realistic multi-layered sheathed spiral strands, a series of
straightforward formulations aimed at practicing engineers were
developed. Numerical results are presented for a number of realistic spiral
strands with diameters as large as 184 mm, covering the full range of
practical wire diameters and lay angles, and experiencing a wide range of
mean axial loads and imposed radii of curvature.
A theoretical model for determining WIre stresses III helical strands
undergoing bending to a constant radius of curvature has also been
proposed. The individual wire bending stresses are shown to be composed
of two components -i.e. those due to presence of interlayer friction and
those due to wires bending about their own neutral axes. The final
theoretical results show that the maximum wire axial stress components
due to interlayer friction are much greater than the corresponding single
wire bending stresses.
Based on theoretical studies on bending hysteresis of axially preloaded
multi-layered spiral strands and previously reported experimental
observations, the structural damping factor in axially pre loaded spiral
strands undergoing lateral vibrations under, say, vortex shedding
conditions can now be predicted.
Closed-form solutions for predicting the extensional-torsional wave speeds
and displacements in axially pre loaded spiral strands experiencing specific
forms of impact loading at one end with the other end fixed, have been
Finally, a theoretical model for estimating the recovery length of a
fractured wire in parallel wire strands prestressed by external wrapping
or clamping have been developed. In this model, the transition from the
full-slip to no-slip interwire friction, as one moves away from the
fractured end, is taken fully into account.