Selection Methodology of High-Cycle Fatigue Analysis Approach for Damage Estimation in Welded Structural Joints

The main purpose of this paper is to provide a summarized general guideline to aid decision making of choosing the type of fatigue analysis approach, best suited for modelling and evaluating high-cycle fatigue damage in welded structural joints. It describes how addition of stress concentration and stress direction information into fatigue assessment methodology affect simulated fatigue damage accumulation results and when it is beneficial or necessary to use a particular fatigue damage estimation approach. The focus is on stress-life curve based approaches, particularly when deciding between variants of nominal, hot-spot or multiaxial fatigue assessment approaches for evaluating fatigue damage within welded joint structures. Evaluation is illustrated through application of proposed methodology to choose and perform fatigue assessment for a non-conventional load-bearing tubular joint structure within a floating lemniscate crane upper arm, which has been observed of being prone to aggressive crack propagation within its welds. Damage within the structure is estimated using two non-optimal fatigue analysis approaches to verify applicability of proposed selection methodology. Results are then summarized through comparative assessment and findings are discussed based on what leads to result changes within each fatigue damage analysis approach.