A Study On The Failure Mode And Accelerated Life Test Of The Permanent Magnetic Bearing In Rotating Machine

Permanent magnetic bearing is an important part in rotating machine.Based on the function and reliability, the design principle for thepermanent magnetic bearing in rotating machine is put forward. FailureMode Effect and Criticality Analysis(FMECA) is studied for thepermanent magnetic bearing, and corresponding designs for magneticbearing are made to enhance the reliability. In addition, the main failuremode and failure causes are found by FMECA, it is found that theadditional alternate magnetic field within the machine causing thepermanent magnet to demagnetize is the main failure mode of thepermanent magnetic bearing in rotating machine. Based on the analysis ofthe failure mode and mechanism, a permanent magnet accelerated lifetesting method is put forward and a test-bed is designed and set up, onwhich the state of permanent magnet being demagnetized by the action ofalternate magnetic field is investigated. By means of the test-bed, anexperiment equivalent to 16.2 years operation of the rotating machineunder normal working condition can be carried out in a relatively shorttime. The variations of the axial magnetic attraction and radial rigidity ofthe permanent magnet are determined. The mathematic model of thedecrease of axial magnetic attraction with time is established. Anexperimental base for life design of the rotating machine permanentmagnetic bearing is provided. The main creative work being involved inthe thesis is: Based on the permanent magnet accelerated life testingmethod which is put forward, and by means of the test-bed which isdesigned and set up, the accelerated life testing is studied for thepermanent magnetic bearing, and valuable research result is acquired.