Nonlinear Dynamic Analysis Of Hydrodynamic Journal Bearings Allowing For Random Roundness Error

As an important part of rotating machinery, the dynamic characteristics and stability of a hydrodynamic journal bearing directly influence the safety operation of the rotating machinery. Roundness error of hydrodynamic journal bearing system is inevitable as a result of the limitation of manufacturing precision, and it directly influences the shape of the hydrodynamic journal bearing oil film, and has obviously influence on hydrodynamic journal bearing dynamic characteristics and stability. The specific shapes method are often used in existing research methods, such as elliptical describe the roundness error of bearing or journal, in exploring the dynamic characteristics of the impact of the system is also only the shaft roundness error, this has a big gap with the engineering practice, for further depict the influences that random roundness error to dynamic characteristics of hydrodynamic journal bearing system, this paper has carried out the nonlinear dynamics research that considering random roundness error of hydrodynamic journal bearing system.Based on the research of hydrodynamic journal bearing system, this article from the beginning of the randomness of roundness error, used mathematical statistics method to describe the random distribution of bearing roundness error, and introduced to the rotor system dynamics analysis and stability study, based on the quality management system requirements of six sigma quality characteristics, set up with a statistical analysis model which obeys Gauss distribution and consists of hydrodynamic journal bearing system. In this paper, applying the normality of Sommerfeld number, judge the correctness of the dynamics model. Based on the theory of nonlinear dynamics, this paper analyzes the bearing, journal of roundness error and the coupling effect, random roundness error of hydrodynamic journal bearing system dynamics, including stability, energy loss, etc. The results show that the influences that shaft roundness error on the stability of the system is more stable with the increase of shaft roundness error, and is greater than the influence of the bearing roundness error.In order to verify the correctness of the theory, this paper studied the critical speed,the axis trajectory and spectrum of the hydrodynamic journal bearing system by the rotor test rig, and at the same time compared related literature theories, verified the correctness of the analysis results in this paper.Research of this paper reveals the random roundness error’s influence on the dynamic characteristics of system of law, made it possible to predict hydrodynamic journal bearingsystem running performance, and provided theoretical basis for tolerance design of hydrodynamic journal bearing and the system diagnosis, to develop low-cost high-performance hydrodynamic journal bearing system laid a theoretical foundation.