Optimized High Energy Vibration Environmental for Four-way Joint Lock Nut of Hydraulic Pipeline in Aircraft Energy Storage Systems

During ground inspection of aircraft hydraulic system, it is found that the lock nut on four-way joint of hydraulic system is loose and the fuse is broken, which will seriously affect normal aircraft operation of energy storage equipment. To grasp the loosening mechanism of four-way locking nut joint of the energy storage device hydraulic pipeline to ensure safe flight, this paper proposes a comprehensive failure analysis of lock nut and fuse for aircraft energy storage systems. In addition, designing a specialized fixture that can withstand high vibration environments to cleverly combine the hydraulic pipeline, four-way joint, locking nut, and other components into actual aircraft installation state. Taking high energy vibration load spectrum of aircraft engine compartment as input vibration excitation condition, the multidirectional ground vibration test is carried out, and the phenomenon of aircraft energy storage systems hydraulic pipeline four-way joint locking nut loosening is reproduced. The experiment found that under continuous high energy vibration environment, the locking nut and anti-corrosion tape continue to wear and produce gaps, which exacerbate the lock nut failure. When the lock nut is rotated 15° clockwise, the preload completely fails and fuse cannot play a protective role in whole process. When lock nut reaches the limit counterclockwise, it is pulled by fuse and hits fuse contact point and safety hole, and fuse continues to wear or even fail. The experimental results show the root cause of four-way joint loose locking nut of hydraulic pipeline, and provide guidance for the safe energy storage and installation process of the aircraft energy storage systems.