The performance behavior of engineering equipment/components in general, and that of equipment subjected to twisting and cyclic load conditions in particular, is very much dependent on surface quality factors. However, the inherent strength and ductility of the materials are not much affected by surface conditions. In the mining industry, wire ropes are widely used for winding and hauling and they are considered to be safety equipment as they concern the personnel as well as damage to structure. Becasue of the complex geometry of the mining operations, wire ropes are subjected to the abuse of bending/crushign compressive/tensile, fatigue and dynamic load cycles. These hostile load conditions seriously damage the rope surface whereby localized stress concentration occurs at the defective sites. Therefore, fatigue strength is reduced to a considerable extent leading to a premature failure. The goal of the paper is to determine the threshold and optimum limits of different types of surface defects, induced during manufacture and use, that become notch sensitive under torsional stresses.
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