• Composites Research
• /
• v.29 no.3
• /
• pp.111-116
• /
• 2016

The tilting pad journal bearing for the turbo compressor application has a role to support high speed and heavy loading rotor. White metal has been widely used for the bearing material but the conventional bearing is immediately suspended and induces serious serious damage to the rotor under the unexpected oil cut situation or the insufficient oil film formation. The carbon fiber reinforced composite having high specific stiffness, specific strength and excellent tribological characteristics can solve these seizure problems. In this work, the study on the durability of high thermal resistance carbon fiber/epoxy composite tilting pad journal bearing under oil cut situation was conducted. The material properties of the composite materials including tensile, compressive and interlaminar properties were measured at room and high temperature of oil cut situation. To investigate the possibility of failure of composite tilting pad journal bearing under oil cut situation, the stress distribution of the composite bearing was analyzed via finite element analysis and the Tsai-Wu Failure index was calculated. To verify the failure analysis results, the oil cut tests for the composite tilting pad journal bearing were conducted using industrial test bench.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.05a
• /
• pp.185-185
• /
• 2004

최근 고속 회전기계에 사용되고 있는 공기호일 베어링은 동압형 기체 베어링으로 매우 안정적이고, 보통의 저널 베어링에서 발생할 수 있는 불안정한 진동을 최소화 할 수 있는 장점을 가지고 있다. 또한 높은 안정성 및 축 자체에 자동 조절 기능을 가지고 있어서 극저온 기계 및 고속 회전기계에 널리 사용되고 있다. 이러한 고속 회전기계는 축의 기동 및 정지 시, 위험속도를 안전하게 통과하기 위해 위험속도에서의 진동을 억제하여야 하고, 운전 가능한 회전수를 증가시키기 위해서 로터 시스템의 동적 해석이 필요하다.(중략)

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2005.05a
• /
• pp.478-483
• /
• 2005

This paper presents the comparison analysis of a Journal and thrust FDB (fluid dynamic bearing) and a conical FDB in a HDD spindle motor. The Reynolds equation is appropriately transformed to describe journal, thrust and conical bearing. Finite element method is applied to analyze the FDB by satisfying the continuity of mass and pressure at the interface between the hearings. The pressure field of the bearings is numerically approximated by applying the Reynolds boundary condition. The load and friction torque are obtained by integrating the pressure and the velocity gradient along the fluid film. The flying height of the spindle motor is measured to verify the proposed analytical result. This research shows that the conical bearing generates bigger load capacity and less friction torque than the journal and thrust bearing in a HDD spindle motor.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.16 no.7 s.112
• /
• pp.746-753
• /
• 2006

This paper proposes a method to calculate the stiffness and the damping coefficients of the coupled journal and thrust bearings. The Reynolds equations and their perturbation equations are transformed to the finite element equations by considering the continuity of pressure and flow at the interface between bearings. The Reynolds boundary condition is used in the numerical analysis to simulate the cavitation phenomena. The dynamic coefficients of the proposed method are compared with those of the numerical differentiation of the loads with respect to finite displacements and velocities of bearing center. It shows that the proposed method is more accurate and efficient than the differentiation method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2006.05a
• /
• pp.666-671
• /
• 2006

This paper proposes a method to calculate the stiffness and the damping coefficients of the coupled journal and thrust bearings. The Reynolds equations and their perturbation equations are transformed to the finite element equations by considering the continuity of pressure and flow at the interface between bearings. The Reynolds boundary condition is used in the numerical analysis to simulate the cavitation phenomena. The dynamic coefficients of the proposed method are compared with those of the numerical differentiation of the loads with respect to finite displacements and velocities of bearing center. It shows that the proposed method is more accurate and efficient than the differentiation method.

• Journal of the KSME
• /
• v.28 no.6
• /
• pp.556-562
• /
• 1988

기계나 구조물의 수명을 결정하는 마멸은 물체간의 접촉으로 인한 것이고 마멸을 줄이기 위해 윤활이 발달되어 왔다. 여러 형태의 마멸을 해석하기 위해서 접촉역학의 이해는 필수적이라 할 수 있다. 하중과 운동 조건에 의한 다양한 접촉문제를 일반적으로 다루기 위해 접촉면을 중심 으로 한 접근 방법을 소개하였으며, 접촉문제의 특이성을 보이기 위해 마찰접촉문제 해석을 위한 한기법을 간단히 기술하였다. 고속 볼 베어링의 특성 해석과 접촉형상 최적설계를 통하여 광 범위한 접촉 역학의 적용의 일부를 소개하였다.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2003.11a
• /
• pp.906-910
• /
• 2003

This paper numerically analyzes the dynamic characteristics of a spindle system supported by two identical journal bearings considering bearing span that has dynamic load due to its mass unbalance. The Reynolds equation is transformed to solve a herringbone grooved journal bearing. The Reynolds equations are solved using FEM in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or angular displacement of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the same bearing spans of upper and lower journal bearings produce the minimum runout and friction torque of a spindle system.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.14 no.9 s.90
• /
• pp.779-784
• /
• 2004

This paper numerically analyzes the dynamic characteristics of a spindle system supported by two identical journal bearingsconsidering bearing span that has dynamic load due to its mass unbalance. The Reynolds equation is transformed to solve a herringbone grooved journal bearing. The Reynolds equations are solved using FEM in order to calculate the pressure distribution in a fluid film. Reaction forces and friction torque are obtained by integrating the pressure and shear stress along the fluid film, respectively. Dynamic behaviors, such as whirl radius or angular displacement of a rotor, are determined by solving its nonlinear equations of motion with the Runge-Kutta method. This research shows that the same bearing spans of upper and lower journal bearings produce the minimum runout and friction torque of a spindle system.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.37 no.2
• /
• pp.241-248
• /
• 2013

In this study, bearings were developed for a high-power propulsion motor operating in inclined operation conditions through a simulation and similitude-experimental methods using commercial rotating machinery dynamics analysis software. The developed journal bearing is electrically insulated and has low thermal conductivity because each part is connected with 2-4 -mm-thick epoxy plates. To realize an appropriate oil thickness, an oil lift system is adopted, and a half separated structure is applied to ensure the feasibility of maintaining very heavy components. This study discusses some of the key design aspects of sleeve bearing design for high-torque and low-speed propulsion motor applications. Furthermore, the conditions of variable slope tests are examined to prevent oil leakage from the bearing lip seal on the test rig.

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.19 no.2
• /
• pp.313-321
• /
• 1995

The effects of the temperature rise and the turbulence are very important factors to predict the accurate performance of a large tilting pad journal bearing. In this study, the dynamic characteristics of a large tilting pad journal bearing are analyzed, taking into account the three dimensional variation of lubricant viscosity and turbulence. The effects of the temperature rise and the turbulence on the stiffness and damping coefficients are investigated in comparison with the results from the laminar or isothermal theory. The stiffness and damping coefficients increase due to the turbulence but decrease due to the temperature rise. The results show that the effects of both the temperature rise and turbulence must be considered simultaneously in order to predict the dynamic characteristics of a large tilting pad journal bearing more accurately.