AXIAL-TORSIONAL COUPLING OF SPIRAL STRANDS UNDER IMPACT LOADING

Coupled extensional-torsional behaviour of axially preloaded multi-lay ered spiral strands under specific forms of impact loading is consider ed. By employing coupled extensional-torsional constitutive equations for steel cables, a pair of wave equations, describing extensional-tor sional displacements at any location along the spiral strand with one end fixed against movement, are obtained. It is argued that, owing to the presence of significant levels of interwire friction, for sufficie ntly small levels of externally applied impact loads on axially preloa ded and fully bedded-in spiral strands, the no-slip (i.e. rigid rod) v ersion of the constitutive relations must be used in preference to the traditional full-slip versions which are the ones often quoted by cab le manufacturers on the basis of their shop measurements. A comparison of numerical results for the wave propagation data based on the no-sl ip and full-slip constitutive relations suggest substantial difference s, which may have significant practical implications for non-destructi ve wire fracture detection devices that are currently under developmen t.