Modeling nonlinear fatigue damage accumulation in a welded runway girder

Abstract

Due to its inherent linear nature, Miner’s damage accumulation rule is widely known to produce unsatisfactory results for lifetime prediction under variable amplitude loading. This can be attributed to its incapability of accounting for load sequence and load interaction effects. In this study, one piece-wise linear and three non-linear damage accumulation models have been implemented in a numerical framework for fatigue lifetime assessment of welded details of industrial assets. Lifetime predictions obtained by these models are first compared to lifetime predictions using Miner’s rule and to experimental data of two-level loading sequences. The results reveal that the studied damage models perform better than Miner’s rule for two-level load sequences within the scope of the studied dataset. Finally the different models are used to estimate the fatigue life of a weld detail that is part of a crane runway girder. A much larger (relative) discrepancy is observed between the lifetime predictions of the different models for a realistic load case than for simple two-level block loads.