Enhanced fatigue life prediction of aviation hydraulic systems: Integrating SQP and data-fitting techniques for pulse load simulation

To overcome the problems of high cost, long cycle time, and difficulty in reproducing the complex working conditions of traditional hydraulic impulse fatigue test methods, this paper proposes a pipeline impulse pressure fitting method based on the Sequential Quadratic Programming (SQP) algorithm. Based on SQP pulse pressure fitting and the fluid-solid coupling (FSI) simulation method, this study analyzes the pulse fatigue life of aerospace hydraulic pipelines made of 4130 structural steel and 6061 aluminum alloy under cyclic pulse pressure in combination, realizing the prediction of the pulse fatigue life of hydraulic pipelines at the design stage. The results show that the absolute error of the pulse waveforms fitted by this method is less than 0.24 MPa, the relative error is less than 1.17%, and the results of pipeline fatigue failure obtained by simulation are consistent with the results of the literature.