In this paper, floating--ring thrust bearings are investigated. A mathematical model is established to analyze the static performance of this kind of bearings, such as the load capacity, frictional power loss, tempera...In this paper, floating--ring thrust bearings are investigated. A mathematical model is established to analyze the static performance of this kind of bearings, such as the load capacity, frictional power loss, temperature rise as well as the angular speed ratio between the floating ring and runner.Meanwhile, a parameter study is also conducted on the characteristics of floating-ring thrust bearings.Finally, the theoretical calculation results are verified by experiments.展开更多
Fluid film bearings are widely used as support elements of rotating shaft for HDD （hard disk drive） spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increas...Fluid film bearings are widely used as support elements of rotating shaft for HDD （hard disk drive） spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increasing because the HDDs are used for various information related equipments such as mobile PCs, car navigation systems. Hence, the rotating shaft has a possibility to come in contact with the bearing and it causes wear or seizure to the bearing surface. In order to avoid the problems, it is extremely important to enhance the dynamic characteristics of the fluid film bearings for spindles. However, verification from both theory and experiment of dynamic characteristics such as spring coefficients and damping coefficients is rare and few. In this paper, the bearing vibration characteristics when the HDD spindle is oscillated are investigated theoretically and experimentally. And then the identification method ofoil film coefficients of fluid film bearing spindles is described.展开更多
Seismic behaviors of base-isolated structures are highly affected by the nonlinear characteristics of the isolated systems. Most of the currently available methods for the identification of nonlinear properties of iso...Seismic behaviors of base-isolated structures are highly affected by the nonlinear characteristics of the isolated systems. Most of the currently available methods for the identification of nonlinear properties of isolator require either the measurements of all structural responses or the assumptions of the proper mathematic models for the rubber-bearings. In this paper, two algorithms are proposed to identify the nonlinear properties of rubber-bearings in base-isolated buildings using only partial measurements of structural dynamic responses. The first algorithm is applicable to the case that proper mathematical models are available for the base isolators. It is based on the extended Kalman filter for the parametric identification of nonlinear models of rubber-bearing isolators and buildings. For the general case where it is difficult to establish a proper mathematical model to describe the nonlinear behavior of a rubber-bearing isolator, another algorithm is proposed to identify the model-tYee nonlinear property of rubber-bearing isolated system. Nonlinear effect of rubber-bearing is treated as ＇fictitious loading＇ on the linear building under severe earthquake. The algorithm is based on the sequential Kalman estimator for the structural responses and the least-squares estimation of the ＇fictitious loading＇ to identify the nonlinear force of rubber-bearing isolator. Simulation results demonstrate that the proposed two algorithms are capable of identifying the nonlinear properties of rubber-bearing isolated systems with good accuracy.展开更多
文摘In this paper, floating--ring thrust bearings are investigated. A mathematical model is established to analyze the static performance of this kind of bearings, such as the load capacity, frictional power loss, temperature rise as well as the angular speed ratio between the floating ring and runner.Meanwhile, a parameter study is also conducted on the characteristics of floating-ring thrust bearings.Finally, the theoretical calculation results are verified by experiments.
文摘Fluid film bearings are widely used as support elements of rotating shaft for HDD （hard disk drive） spindle motors. Recently, the opportunity for the HDD spindle motors exposed to external vibration has been increasing because the HDDs are used for various information related equipments such as mobile PCs, car navigation systems. Hence, the rotating shaft has a possibility to come in contact with the bearing and it causes wear or seizure to the bearing surface. In order to avoid the problems, it is extremely important to enhance the dynamic characteristics of the fluid film bearings for spindles. However, verification from both theory and experiment of dynamic characteristics such as spring coefficients and damping coefficients is rare and few. In this paper, the bearing vibration characteristics when the HDD spindle is oscillated are investigated theoretically and experimentally. And then the identification method ofoil film coefficients of fluid film bearing spindles is described.
基金supported by the National Natural Science Foundation of China(Grant No.51178406)the Research Funding from the State Key Laboratory for Disaster Reduction in Civil Engineering at Tongji University(Grant No.SLDRCE10-MB-01)the Fujian Natural Science Foundation Project(Grant No.2010J01309)
文摘Seismic behaviors of base-isolated structures are highly affected by the nonlinear characteristics of the isolated systems. Most of the currently available methods for the identification of nonlinear properties of isolator require either the measurements of all structural responses or the assumptions of the proper mathematic models for the rubber-bearings. In this paper, two algorithms are proposed to identify the nonlinear properties of rubber-bearings in base-isolated buildings using only partial measurements of structural dynamic responses. The first algorithm is applicable to the case that proper mathematical models are available for the base isolators. It is based on the extended Kalman filter for the parametric identification of nonlinear models of rubber-bearing isolators and buildings. For the general case where it is difficult to establish a proper mathematical model to describe the nonlinear behavior of a rubber-bearing isolator, another algorithm is proposed to identify the model-tYee nonlinear property of rubber-bearing isolated system. Nonlinear effect of rubber-bearing is treated as ＇fictitious loading＇ on the linear building under severe earthquake. The algorithm is based on the sequential Kalman estimator for the structural responses and the least-squares estimation of the ＇fictitious loading＇ to identify the nonlinear force of rubber-bearing isolator. Simulation results demonstrate that the proposed two algorithms are capable of identifying the nonlinear properties of rubber-bearing isolated systems with good accuracy.
