Research On The Reliability Test Method Of FAST Hydraulic Actuator

Five-hundred-meter aperture spherical radio telescope(hereafter called FAST)is the major infrastructure project in china,and it will be the largest single-dish radio telescope upon its completion in the world.The actuator is the core power control unit in the FAST,2225 actuators will work together for long continuous time at the site of FAST which is situated at Guizhou province of China.The working condition is terrible,therefore the reliability requirement of hydraulic actuator is very high.Failure mode and hazard analysis are implemented for the actuator,the result shows that gear pump,relief valve and check valve are the weakest points of the reliability for the hydraulic system of the actuator.But the traditional reliability test of hydraulic components is time-consuming and low efficiency with high energy consumption.Besides,the number of the single test samples is limited and each kind of test circuit can only test a kind of hydraulic components.To solve the last two problems,this thesis has described the design of multi-components parallel reliability test device of hydraulic actuator.This device can test the reliability of two gear pumps,two relief valves and two check valves,the energy-saving rat can reaches 53%.This thesis has also designed the condition monitoring and control system based on PLC and configuration software,by which we realizing the automation of the test process.To solve the problem of time-consuming,an accelerated life test method with two stage of constant stress has been proposed in this thesis.This method takes pressure as the accelerated stress to shorten the test time;on the basis of performance degradation theory and best linear unbiased estimation.Then render the whole life test curve of reliability characteristic parameters by MATLAB software,and convert these into reliability index under the rated conditions.The repetitive failure and the critical failure which were exposed in reliability verification test of hydraulic actuators have been analyzed deeply by the theory of active testing,and corresponding reliability growth measures were proposed to ensure the high reliability of FAST hydraulic actuator.Besides,the research results have important guiding significance and project application value for energy-saving design and accelerating design of domestic hydraulic components reliability test platform.