Pre-Use Inspection

A theory which predicts when a wire in an impacted strand will separate from the core wire is presented. The condition must occur if a strand is to form a bird cage. It is shown that it is possible to separate even if the axial strain is positive. The wires can separate, due to twisting, with a reduction in tensile load. If rope is carrying a heavy load and the load is partially released, wire separation is possible. The theory can be extended to wire ropes with complex cross sections.