PSI - Issue 75

Bruno Depale et al. / Procedia Structural Integrity 75 (2025) 254–261 Bruno Depale/ Structural Integrity Procedia (2025)

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Fig. 5. CAD of cantilever local modeling

5. Results and Residual Life Assessment (RLA) The stress histories at any selected point of the LBB structure depend on the moving loads, i.e., the types of trains, their frequency and their line-up: all this input data is described in our clause 3. After having performed movable load methodology with RM Bridge software for the four types of train line-up, force histories are obtained for each structural detail under consideration which include moments and forces (shear and axial). From those force histories are derived stress histories that are used below for RLA. 5.1. Fatigue damage using Rainflow counting For each sequence of force/stress resulting from a movable load due to any train line-up, the Rainflow counting method is applied, transforming the sequence into stress history (see principle EN 1993-1-9, Fig. A.1). Then, the well-known and simple Palmgren-Miner rule (1945) is applied, this linear damage accumulation theory assumes that each stress cycle result in a proportional amount of damage. The cumulative damage D is calculated with: =∑ (1) Where n i is the number of cycles of stress amplitude/range σ i applied and N i is the total number of cycles that would result in a fatigue failure, for this given stress amplitude, acting alone. The end of fatigue life is given by reaching: ≥ 1 (2) 5.2. Available S-N curves and corrosion effect Concerning available S-N curves for riveted connections, we may notice: