Study on fatigue life of aircraft hydraulic pipeline under stress damage of water hammer and vibration

Aircraft hydraulic system requires that the structure of the hydraulic pipeline should be as light as possible and the stiffness and strength should be as higher as possible. However, the hydraulic pipeline always has the destructive stress such as vibration and pressure pulse, resulting in the aircraft on the hydraulic piping requirements are particularly high, This is a contradiction. Aiming at how to balance these contradictions, this paper studies the simulation and analysis of the stress and fatigue life of the pipeline under the condition of water hammer wave and vibration. First of all, a model of water hammer wave is established to simulate the pressure of the specimen. Then, the mathematical model of the vibration stress of the pipeline is set up, and the equivalent stress of the uniaxial force of the pipeline is calculated. The water hammer wave and the vibration superimposed stress curve are obtained. Finally, the fatigue life of the pipeline is simulated by fracture and damage mechanics. The research results show that the fatigue life of hydraulic pipeline coincides with the actual fault failure life under the condition of water hammer pulse and vibration superposition.