Fatigue damage mechanisms in steel cable under bending loading

Abstract

Steel cables can be employed as reinforcements in complex structures. During their use in service, they might be subjected to cyclic loadings leading to fatigue damage. This work deals with the fatigue damage evolution in steel cables used in tires, when subjected to cyclic bending loadings corresponding to some extreme in-service uses of tires. The studied cables are embedded in an elastomer matrix, as required for this application. First, a specific experimental device has been developed to test elastomer-steel cable composite specimens. In order to study damage mechanisms, specimens were observed in a bent position using X-ray tomography after fatigue testing. Crack distribution was analyzed for two distinct loading amplitudes. SEM observations of the crack initiation zones were also made to complete the analysis. Secondly, finite-element analysis was carried out. The bent cable and its matrix were simulated both with and without broken wires, in order to evaluate the impact of the first breakage on the stress distribution within the cable. Eventually, the combination of observations and simulations allowed to propose two damage mechanisms, depending on the loading severity.