Fatigue Failure of a Steel Wire Rope Resulting From Shock Loading

The 11 mm diam 8 x 19 fiber-core rope, constructed from improved plow steel wire, on the cleaning-line crane failed while lifting a normal load of coils after five weeks of service. Several broken wires and fraying of the fiber core were revealed by visual examination of a section of the wire rope adjacent to the fracture. Fatigue cracks originating from both sides of the wire were revealed by microscopic examination of a longitudinal section of a wire. The diam of the sheave on the bale (27 cm) was found to be slightly below that specified for the 11 mm diam rope. It was observed that the sudden shock received by the hook in rolling the coils over the edge of the rinse tank after pickling caused vibration which was most severe at the clamped end of the rope. It was concluded that this caused the fatigue failure of the rope. As a corrective measure, the diam of the sheave was increased to 33 cm and pitched roll plates were installed between the tanks where rolling of coils was required.