A hydraulic pressure pulse equipment that can generate water hammer and trapeziumshaped wave for testing hydraulic pipes and components of aircrafts is introduced. The mathematical models of the pressure transient state of the pipes and components, such as the accumulator, the proportion valve, the supercharger etc., have been developed and used to analyse the factors that affect the pulse parameters. The control method of the trapeziumshaped wave and the water hammer wave is also discussed. The closedloop control to trail ideal waveform with actual pressure can be used to produce trapeziumshaped wave. By making use of water hammer phenomenon and regulating the proportion valves automatically, water hammer waves can be produced, and the feature parameters of the waveform, such as the slope and the peak value etc., can be controlled. The simulation and test results are presented.

Controlled Pressure Pulses for Testing Hydraulic Pipes and Components of Aircrafts

Fatigue test machine is a kind of experimental equipment designed to test the life-span of components. In general, it has four sections: computer, controller unit, hydraulic system and the test piece. A fatigue test machine about oil cooler was built up based on DCS (Distributed Control System) in this paper. And in order to improve the hydraulic pressure accuracy in the system, which influences a lot on the test validity, a repetitive controller was applied in the system. The simulation results indicated that the controller improved the pressure accuracy a lot, and it also made the system robust to some uncertain parameters.

Fang Qi

Papers

Repetitive Control for the Improvement of Pressure Tracking in Fatigue Test Machine