The Reliability And Sensitivity Analysis On Oil Instability Of Jeffcott Rotor Systems

With the improvement of technology and the development of modern industry,rotating machinery is taking more and more greater part in many fields such astransportation, national defense and chemical industry and etc., and the study of thedynamics of rotating machinery receives more and more recognition. Acomplicated machine system may vibrate violently due to nonlinearity thatinherently exists in the system and multi-kind of faults, great tragedy may occur ifthe vibration is violent enough, which can cause the machine to destroy and theoperators to death. So it signifies much to study the nonlinear dynamics of faultingrotor systems and the technology to diagnosis the faults. Researchers all over theworld made much study in these fields and made great progress.The study of the dynamic model of a certain type of rotating machinery canhelp the design and operation of this type of rotating machinery. However, in mostcases, some parameters of the dynamic model should be set to uncertain. Theparameter's uncertainty is caused by uncertainty of engineering material properties,errors of manufacture and installation, and also, varying working condition, variousloads and process can contribute to the uncertainty of parameter of dynamic system.A set useful sensitivity analysis of uncertain parameters of the normally operatingrotor system can help to know which parameters should be controlled strictly whendesigning and manufacturing so can help the tolerance setting in designing. A setuseful sensitivity analysis of uncertain parameters of the fault rotor system can helpto know which parameters should be changed firstly to diminish the fault. Theanalysis of reliability of the rotating machinery can help to find the safety of everypart of the machine, the mechanical parts which has lower reliability can beredesigned, this can help the avoiding of fault happening, and also the design canbe evaluated by the reliability of the machine. So the sensitivity analysis, reliabilityanalysis has practical applications within rotating machinery design, manufacturing,operation and maintenance.The fault diagnosis means much to the safe operation and maintenance of therotating machinery, Researchers all over the world made much study and madegreat progress in fault mechanism and diagnosis technology. Great economicbenefits and society benefits are achieved. The development of modern industryrequire quick diagnosis of fault location and fault extent, so the precision diagnosismade great progress worldwide, and made application in real manufacturing.The main works are as follows:Combining the generalized probabilistic perturbation finite element methodand shooting method together to study the uncertain periodic response of journalbearing-rotor system. The statistical fourth moment method is used to determinethe first four moments of system response and state function. The distributionfunction of the system state function is approximately determined by the standardnormal distribution functions using the Edgewoth series technique. The reliabilityand reliability sensitivity are obtained and the effect on reliability and reliabilitysensitivity of rotor response is studied. The result can help the design and using ofrotating machinery.