Research On The Reliability Growth Test Method Of FAST Hydraulic Actuator

Five-hundred meter Aperture Spherical radio Telescope(Abbreviated as FAST)is the major infrastructure project in China.It has been the largest and most sensitive single-aperture radio telescope in the world.Hydraulic actuator is the core power control unit of FAST active reflector system.In the observation operation,2225 hydraulic actuators are coupled with each other and work together.At the site of FAST,even though the working condition is terrible,it needs all actuators stable operation for long continuous time,therefore the reliability requirement of hydraulic actuator is very high.In this paper,after the experimental investigations on FAST actuator's hydraulic system's reliability test,the research work of practicing reliability growth is carried out.At first,taking analysis of the failure mode and hazard degree of the FAST actuator's hydraulic system in theory.A preliminary reliability assessment of the hydraulic system is made.The MTBF time of the actuator is determined.Then traditional test method for reliability test is time-consuming,inefficient and test means is limited.The hydraulic active test theory and the test method of active tester are introduced,which can effectively improve the test efficiency and improve the accuracy of determining the fault point.Thirdly,an on-line reliability test device for hydraulic actuators is used to test the reliability of the actuators.The test device is equipped with a variety of sensors,combined with data acquisition technology.Multiple operating data of the FAST actuators could be collected at the same time.The whole process monitoring of hydraulic reliability test for hydraulic actuators is realized.To solve the problem of time-consuming,the constant stress accelerated life test method is used to shorten the test time with the working load and the speed of the actuator as the acceleration factor.The failure characteristics and weak links of the FAST actuator are fully exposed in a short time.The reliability of the FAST hydraulic actuators is verified and analyzed by test.Finally,a deeply analysis of the repetitive and critical faults exposed by the hydraulic actuators in the reliability test is carried out.A deeply research on the failure mechanism of design defects in the system is taken.And the corresponding measures of reliability growth are put forward to ensure thehigh reliability of the FAST hydraulic actuators.In addition,the test method applied in this paper has important theoretical guidance and practical application significance for acceleration test method and reliability growth research method of hydraulic actuator product reliability.