Bandwidth‐Corrected Dirlik Method for Vibration Fatigue Damage Assessment of Critical Structures in High‐Speed Trains

ABSTRACT Frequency‐domain methods enable efficient vibration fatigue assessment of high‐speed train structures under stationary Gaussian assumptions, but their accuracy remains sensitive to the bandwidth characteristics of the stress power spectral density. Based on field‐test stress measurements, stationary Gaussian stress segments were extracted, and the corresponding time‐domain rainflow‐counting damage was calculated as the benchmark for evaluating frequency‐domain prediction accuracy. A practical 5RMS stress‐amplitude boundary was proposed as an engineering upper integration bound for fatigue‐damage calculation. A bandwidth‐corrected Dirlik method was further developed by introducing a bandwidth‐dependent correction coefficient into the original formulation. The resulting method retains the probabilistic structure and computational efficiency of the original Dirlik model, while improving bandwidth adaptability and reducing the maximum prediction error from approximately 50% to below 10%. Validation using representative train‐structure stress responses confirms the applicability of the proposed method to stationary Gaussian and PSD‐based fatigue assessment scenarios.