Nonlinear dynamic behavior of a water-lubricated hybrid bearing-rotor system
In this study, the stability analysis is carried out on a water-lubricated hybrid bearings used as the support of a high-speed motorized spindle. A two-dimension finite element method considering turbulence effect has been developed to solve the nonlinear oil film force. This paper mainly studies the influence of the water supply pressure, rotating speed, and unbalance mass on the axis orbit of the rotor-bearing system. The results of the axis orbit indicate that the effect of nonlinear for the hybrid bearing studied in this paper is not obvious, and the bearing-rotor system can run safely and stably at the rotating speed not more than 30000 rpm.
Experimental analysis on friction-induced vibration of water-lubricated bearings in a submarine propulsion system
Abstract Abnormal vibration and noise, originated from friction and wear, are often found in water-lubricated stern-tube bearings, which seriously threatens the safety and concealment of underwater vehicles. In order to better understand the friction-induced vibration in water-lubricated stern-tube bearings, friction pairs of rubber specimens matched with ZQSn10-2 brass were tested on the water-lubricated bearing test rig SBB-100. A high-speed camera was used to track the micro images that focused on of the rubber layer vibration motion, while a machine vision technique also was employed to extract the friction-induced vibration of the test bearings. The experimental analysis results demonstrate that the bearing vibration was mainly induced by stick-slip. Furthermore, the orthogonal experiment method was used to distinguish the key factors that induce the bearing vibration among rotating speed, contact pressure, rubber layer hardness and thickness, and lubrication condition. The analysis results indicate that the importance of factors is sorted in the order of lubrication condition, contact pressure, hardness and thickness of rubber layers. In normal lubrication condition, the intensity of friction-induced vibration of the rubber bearings can be reduced by increasing the hardness of the rubber layer, decreasing the contact pressure, and the thickness of the rubber layer.
Seeing Like a Racial State: the Census and the Politics of Race in the United States, Great Britain and Canada
ii Acknowledgements iv List of Abbreviations vii List of Tables ix List of Appendices x Chapter 1 Invitation 1 Chapter 2 Orientation 26 Chapter 3 Mark One or More: Census Politics in the United States 61 Chapter 4 The Ethnic Question: Census Politics in Great Britain 115 Chapter 5 (In)Visible Minorities: Census Politics in Canada 168 Chapter 6 Seeing Like a Racial State 234 Chapter 7 Alternatives and Outcomes in the Census Policy Sphere 310 Chapter 8 Conclusions 364 Reference List 382