FAN Ze-ming1, CAO Yang1, LIANG Zhen-tao1, FU Dian-yu2

(1.The School of Automation, Northwestern Polytechnical University, Xi′an 710129, China; 

2.Shenyang Machine Tool(Group) Co., Ltd., Shenyang 110041, China)

Abstract: Aiming at failure problems of aircraft hydraulic pipeline, the model of water hammer pulse was applied to fatigue life test, the variation of stresses of the hydraulic line with the simply supported structure, which was used usually for the ground test of the aircraft hydraulic line, was analyzed under the pulse of water hammer. At first, the stress was analyzed without oil in the line, the place of maximal stress was determined. Further, the mathematical model was built and the stress was analyzed with the simulation, the result of line will soon be destroyed in resonance condition was concluded. At last, the theoretical fatigue life was predicted by applying damage-mechanics. The results indicate that the theoretical fatigue life should be falling fast with the increase of the maximum stress and the period of the maximum stress, and it is consistent with condition of actual hydraulic line failure.

Key words: water hammer; simply supported beam; vibration stress; hydraulic line; life prediction