The fatigue of wire rope subject to corrosion and mechanical damage

RoundTable – ENDURANCE RESEARCH OF WIRE ROPE AND ITS PRACTICAL APPLICATIONS – Glasgow 1985

Fatigue tests have been performed in laboratory air and ASTM seawater on samples of 8 mm diameter 6 x 36 steel wire rope. Tests were performed at a frequency of 1 Hertz, using a purpose-built servo-hydraulic test machine. In addition to tests on undamaged rope, the fatigue behaviour of samples which have been artificially damaged has been investigated. The S-N curves for the two environments show a marked reduction in the fatigue strength of the rope in seawater compared to air. It is suggested that this is due to a dissolution process which affects the initiation and early stages of growth of the fatigue cracks. Mechanical damage in the form of kinks has resulted in reduction of the fatigue life in air to a similar value to that obtained in seawater. Examination of failed rope samples has shown that the number of wire breaks at failure varies widely according to the load history and the test environment, and it is suggested that wire break density is not a good discard criterion.

Author(s): R.A. Cottis & Z. Husain