Calibration of a numerical prediction methodology for fretting-fatigue crack initiation in overhead power lines

Abstract

A methodology is developed for the prediction of fretting fatigue phenomenon that results in crack initiation in strands of overhead power line conductors. A numerical approach based on finite element analysis is used to obtain the local stress and strain fields for application of crack initiation criteria in the high cycle fatigue regime. Solutions for the stress field in the stabilised state, where further loading cycles no longer introduce changes to the plastic deformation, are obtained using the stationary incremental method. Cases where convergence does not occur due to significant ratcheting are disregarded as low cycle fatigue. Post-treatment analysis that includes localised averaging is used to implement a fatigue criteria that estimates the crack initiation risk. Validation of this approach is made by comparing with results obtained from experimental measurements made on a simplified clamp wire configuration. Analyses of a simplified three-dimensional configuration with fretting is presented for a range of loading parameters and qualitative trends are established, which will prove invaluable for lifespan assessment of overhead power lines.