Optimal Transport Meshless Method Based Fatigue Life Calculation Method for Hydraulic Pipelines under Combined Excitation

The issue of fatigue in modern hydraulic pipelines is increasingly severe, and there remains a lack of effective prediction methods for pipeline fatigue life. In practical engineering, hydraulic pipelines are primarily subjected to random excitation and fluid excitation, representing a typical composite excitation. Most current research relies on solutions considering only single excitations, which leads to inaccuracies. To accurately calculate the fatigue life under composite excitation, this study incorporates resonance excitation and pulsation excitation into the optimal transport meshless method (OTM) within a strong fluid–structure coupling computational framework. Subsequently, by utilizing the hazard point method based on obtained stress data, an estimation of the service life for engine hydraulic lines can be determined. This work provides both practical guidance and theoretical insights for designing hydraulic lines in modern aircraft.