• Title/Summary/Keyword: a rigid disk

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Experimental and Numerical Study on an Air-Stabilized Flexible Disk Rotating Close to a Rigid Rotating Disk (회전원판 근처에서 회전하는 유연디스크에 대한 실험 및 수치해석)

  • Gad, Abdelrasoul M.M.;Rhim, Yoon-Chul
    • Transactions of the Society of Information Storage Systems
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    • v.5 no.1
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    • pp.19-35
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    • 2009
  • The present work is an experimental and analytical study on a flexible disk rotating close to a rigid rotating disk in open air. In the analytical study, the air flow in the gap between the flexible disk and the rigid disk is modeled using Navier-Stokes and continuity equations while the flexible disk is modeled using the linear plate theory. The flow equations are discretized using the cell centered finite volume method (FVM) and solved numerically with semi-implicit pressure-linked equations (SIMPLE algorithm). The spatial terms in the disk equation are discretized using the finite difference method (FDM) and the time integration is performed using fourth-order Runge-Kutta method. An experimental test-rig is designed to investigate the dynamics of the flexible disk when rotating close to a co-rotating, a counter-rotating and a fixed rigid disk, which works as a stabilizer. The effects of rotational speed, initial gap height and inlet-hole radius on the flexible disk displacement and its vibration amplitude are investigated experimentally for the different types of stabilizer. Finally, the analytical and experimental results are compared.

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Finite Element Analysis of Vibration of HDD Disk-Spindle System with Rigid Complex Spindle and Flexible Shaft (복잡한 형상의 강체 스핀들과 유연축을 고려한 HDD 디스크-스핀들 계의 고유진동 유한요소해석)

  • Lee, Sang-Hoon;Jang, Gun-Hee
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2000.11a
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    • pp.784-789
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    • 2000
  • Equations of motion are derived and solved using the finite element method substructure synthesis for the disk-spindle system with rigid spindle and flexible shaft. The disk is modeled as a flexible spinning disk by Kirchhoff plate theory and von Karman nonlinear strain. The spindle supporting the flexible disk is modeled as a rigid body to consider its complex geometry. The stationary shaft supporting the rotating disk-spindle-bearing system is modeled by Euler beam, and the ball bearings are modeled as the stiffness matrix with 5 degrees of freedom. Developed theory is applied to analyze the vibration characteristics of a 3.5" HDD and a 2.5" HDD, respectively, and modal tests are performed to verify the simulation results. This paper shows that the developed theory can be effectively applied to the rotating disk-spindle system with the spindle of complex shape.

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Spectral Element Modeling for Rotating Shafts (회전축에 대한 스펙트럴요소 모델링)

  • Lee, Jea-Sang;Yong, Suk-Jin;U-Sik, Lee
    • Proceedings of the KSR Conference
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    • 2007.05a
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    • pp.749-754
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    • 2007
  • In this paper, the vibration of a rotating shaft with a thin rigid disk is considered. It is assumed that the shaft has uniform, circular cross-section. Based on the Timoshenko-beam theory, the transverse displacements and slops in two lateral directions, the axial displacement, and the torsional deformation are considered. The spectral element method is used for the vibration analysis of the rotating shaft with a thin rigid disk, which is modeled by two shaft elements and a thin rigid disk element.

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FUTURE HEAD/MEDIA TECHNOLOGIES IN RIGID DISK DRIVES

  • Byun, Chong-Won
    • Proceedings of the Korean Magnestics Society Conference
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    • 1994.03a
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    • pp.12-13
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    • 1994
  • Magnetic recording is still considered to be a.leader in storage industries in general. The rigid disk drive, in particular, has an advantage over tape, optical, magneto-optical, or flash memories, because of high areal density and fast access time with reasonably low cost per Mbyte. However, to be competitive in the market and to keep an edge over other storage devices, head and media in rigid disk drives require better performance per cost and more aggressive improvement in areal density, as shown in Fig. 1, than before. In this review paper, the future trend in head/media technologies of the rigid disk drive has been reviewed. Thin film media and thin film inductive/MR heads will be mainly discussed, since they are expected to be dominant in the future high-end drives over other technologies, such as particulate media or MIG heads.(omitted)mitted)

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Process Design in Superplastic Forging of a Jet Engine Disk by the Finite Element Method (유한요소법을 이용한 제트엔진 디스크의 초소성 단조공정설계)

  • 이진희;강범수;김왕도
    • Transactions of the Korean Society of Mechanical Engineers
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    • v.18 no.4
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    • pp.876-886
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    • 1994
  • Process design in superplastic forming to produce a Nickel-base jet engine disk has been carried out using the rigid-viscoplastic finite element method. This study aims at deriving systematic procedures in forging of superalloy engine disk, and develops a simple scheme to control strainrate within a range of superplastic deformation during the forging operation. The new process, a pancake type preform being used, is designed to have less manufacturing time, and more even distribution of effective strain in the final product, while the conventional superplastic forging of an engine disk has been produced from a cylindrical billet. The jet engine company, Pratt & Whitney, provided the basic information on the manufacturing process of superplastic forging of a jet engine disk.

GYROSCOPIC EFFECT ON MODE SPLITTING IN ROTATING DISK: HDD SPINDLE SYSTEM VIBRATIONS

  • Lee, Chong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 1997.10a
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    • pp.43-49
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    • 1997
  • A rotating rigid disk, attached on a flexible shaft or supported by a torsional spring, experiences precessional whirling due to gyroscopic moment loading. It is well known in rotor dynamics area that, as the rotational speed increases, the precessional mode of the rotating rigid disk starts splitting into two: forward and backward precessional modes. On the other hand, it is also well known in disk vibration area that a rotating flexible disk also shows another kind of mode splitting phenomenon due to the rotation, resulting in forward and backward traveling waves. When rotating multiple flexible disks are coupled in vibration with the supporting Flexible shaft, the associated mode splitting should be compatible with the two seemingly different vibration analysis methods. This paper investigates the possibility of fusing the precessional and traveling wave mode splittings so that the bending coupled disk vibrations in HDD spindle systems can be better understood.

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Spectral Element Modeling of Rotating Shafts by Using Variational Method (변분법을 이용한 회전축의 스펙트럴요소 모델링)

  • Yong, Suk-Jin;Lee, Jae-Sng;Lee, U-Sik
    • Proceedings of the KSR Conference
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    • 2007.11a
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    • pp.923-926
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    • 2007
  • In this paper, the vibration of a rotating shaft with a thin rigid disk is considered. It is assumed that the shaft has uniform, circular cross-section. Based on the Timoshenko-beam theory, the transverse displacements and slops in two lateral directions, the axial displacement, and the torsional deformation are considered. A spectral element model is developed by using the variation method for the vibration analysis of the rotating shaft with a thin rigid disk, which is modeled by two shaft elements and a thin rigid disk element. The result of vibration analysis by finite element method is compared to the result of this research.

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Spectral Element Modeling of the Rotating Shafts on Bearing Supports (베어링으로 지지된 회전축의 스펙트럴요소 모델링)

  • Lee, Jae-Sng;Lee, U-Sik
    • Proceedings of the KSR Conference
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    • 2008.06a
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    • pp.826-830
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    • 2008
  • In this paper, the vibration of a rotating shaft with a thin rigid disk on bearing supports is considered. It is assumed that the shaft has uniform, circular cross-section. Based on the Timoshenko-beam theory, the transverse displacements and slops in two lateral directions, the axial displacement, and the torsional deformation are considered. And flexible supports are used to analyse the bearings. A spectral element model is developed for the vibration analysis of the rotating shaft with a thin rigid disk, which is modeled by two shaft elements and a thin rigid disk element. The result of vibration analysis by finite element method is compared to the result of this research.

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Vibration Analysis of Rotating Disk-Spindle System Using Finite Element Method and Substructure Synthesis (유한 요소법과 부분 구조 합성법을 이용한 회전 디스크-스핀들 계의 진동 해석)

  • Jeong, Myeong-Su;Jang, Geon-Hui
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.9 s.180
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    • pp.2201-2210
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    • 2000
  • Vibration of a rotating disk-spindle system is analyzed by using Hamilton's principle, FEM and substructure synthesis. A rotating disk undergoes the rigid body motion and the elastic deformation. It s equation of motion is derived by Kirchhoff plate theory and von Karman nonlinear strain. A rotating shaft is described by Rayleigh beam theory considering the axial rigid body motion. The stationay shaft supporting the rotating disk-spindle-bearing system is modeled by Euler beam theory, and the stiffness of ball bearing is determined by A.B.Jones' theory. FEM is used to solve the derived governing equations, and substructure synthesis is introduced to assemble each structure of the rotating disk-spindle system. The developed theory is applied to the spindle system of a 35' computer hard disk drive with 3 disks to verify the simulation results. The simulation results agree very well with the experimental ones. The proposed theory may be effectively expanded to the complex structure of a disk-spindle system.

Application of FEM to the Forming Process of Disk-Brake Piston (유한요소법을 이용한 disk-brake piston의 공정설계)

  • 황병복;이호용
    • Transactions of Materials Processing
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    • v.3 no.2
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    • pp.178-188
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    • 1994
  • A design methodology is applied for manufacturing a disk-brake piston component. The design criteria are the limit drawing ratio and the forging load within the available press limit. Also, the final product should not have any geometrical defect. The rigid-plastic FEM has been applied to simulate the conventional four stage manufacturing processes, which include deep drawing and forging process. Simulation of one stage process from a selected stock to the final product shape is performed for generating information on additional requirements for metal flow. Two stage forming processes with different punch corner and nose geometries are also simulated to identify the possible best solutions. Finally, the best manufacturing process is selected, which is using a hemispherical punch int he deep drawing process.

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