• Structural Engineering and Mechanics
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• 제24권5호
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• pp.515-528
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• 2006

This article presents a unified analytical solution for the analysis of thermal deformations and stresses in elastic annular disks with arbitrary cross-sections of continuously variable thickness. The annular disk is assumed to be under steady heat flow conditions, in which the inner surface of the annular disk is at an initial temperature and the outer surface at zero temperature. The governing second-order differential equation is derived from the basic equations of the thermal annular disks and solved with the aid of some hypergeometric functions. Numerical results for thermal stresses and displacement are given for various annular disks. These disks include annular disks of thickness profiles in the form of general parabolic and exponential functions. Additional annular disks with nonlinearly variable thickness and uniform thickness are also included.

• 한국소음진동공학회논문집
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• 제19권12호
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• pp.1338-1346
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• 2009

We present a one-dimensional annular plate element with which the in-plane vibration of full disks can be analyzed efficiently and accurately by using the FEM. Its elementary mass matrix and stiffness matrix are derived, respectively, from the virtual work by effective forces and the virtual strain energy. The static deformation modes obtained from an integration of the differential equilibrium equations of the annular plate are used as interpolation functions of the one-dimensional annular plate element. The in-plane natural vibration characteristics of a 2-step full disk and a uniform full disk are analysed. Its results are compared with the results obtained by utilizing two-dimensional 8-node quadrilateral plane elements and cyclic symmetry of the disk. And also, by comparing with the theoretical results of previous researchers, the efficiency and accuracy of the presented element are verified.

• 한국소음진동공학회논문집
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• 제16권2호
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• pp.169-175
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• 2006

Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks). Higher data transfer rate in data storage disks could not be achieved by polycarbonate disks in the present market. The problem can be solved by applying the fiber-reinforce composite materials to the disks. In this paper, an application of composite materials to rotating disks is proposed to increase the critical speed. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating composite disks by the Galerkin method. The orthogonal functions are used in series solution. A companion paper(Part II) presents and discusses the numerical results of vibration analysis and critical speed for rotating polar orthotropic disk using the formulation and solution method given in this paper (Part I).

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.337-340
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• 2005

Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks). Higher data transfer rate in data storage disks could not be achieved by polycarbonate disks in the present market. The problem can be solved by applying the fiber-reinforce composite materials to the disks. In this paper, an application of composite materials to rotating disks is proposed to increase the critical speed. Dynamic equation is formulated in order to calculate the natural frequency and critical speed for rotating composite by the Galerkin method. The results show that the radially reinforced disk is more effective in increasing critical speed than the circumferentially reinforced disk.

• 한국철도학회논문집
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• 제15권6호
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• pp.588-596
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• 2012

이 논문은 두꺼운 디스크의 면외 고유 진동을 유한 요소법을 사용하여 회전 관성 및 횡 전단 변형의 효과를 포함하면서 단순하고 효율적으로 정밀하게 해석할 수 있는 새로운 준-해석적 환상 민드린 평판 요소를 제시한다. 환상 민드린 평판의 평형 방정식의 정확한 해인 정적 변형 모드를 사용하여 요소의 보간 함수, 강성 및 질량 행렬은 절 직경 수에 대하여 유도되며, 이와 같은 요소는 면외 강체 운동을 정확하게 표현할 수 있고 전단 잠김이 없다. 제시된 요소를 적용하여 동심 링으로 지지되거나 지지되지 않은 균일 디스크 및 다단 디스크의 고유진동수를 해석하고, 그 결과를 선행 연구의 이론적 결과 또는 2차원 쉘 요소를 사용하여 얻어진 유한요소 해석 결과와 비교하여 제시된 요소의 수렴성 및 정확성을 조사하였다.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2005년도 춘계학술발표대회 논문집
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• pp.176-179
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• 2005

Rotating annular disks are widely used in data storage devices such as CDs, DVDs(digital versatile disks), and HDs(hard disks) as well as in traditional industrial machines like sawing machines, turbines, brake disks. The exact stress distribution of rotating polar orthotropic disk is derived by solving directly the equilibrium equation instead of using stress function. Stress distributions for typical GFRP and CFRP disks are presented in addition to polycarbonate disk. The results show that the application of CFRP to rotating disk can increase the maximum allowable rotating speed but this may not be applicable to GFRP disk.

• 한국소음진동공학회논문집
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• 제19권5호
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• pp.537-544
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• 2009

In order to increase the critical speed of rotating disks of which functional material could not be changed such as in optical and magnetic data storage disks, a new disk with a rim reinforced by composite material is proposed and its concept is verified by numerical analysis. Stress distributions are found for the rotating disk composed of two annular disks of which materials are isotropic inside and orthotropic outside. Dynamic equation is formulated in order to calculate the natural frequency and critical speed. For the solution of lateral vibration, a rotational symmertry condition is applied along circumferential direction and a finite element interpolation with Hermite polynomial is performed along the radial direction to obtain a proper solution. According to the results, reinforcing a disk at rim makes critical speeds drastically increased, and induces a buckling phenomenon in mode (0,0) which occurs over the lowest critical speed.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2000년도 춘계학술대회논문집
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• pp.1609-1614
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• 2000

This paper presents the modeling, theoretical formulation, and stability analysis for a combined system of a spinning disk and a head that contacts the disk. In the analytical model, head interface is considered by a rotating mass-spring-damper system together with a frictional follower force on the damped annular disks. The method of multiple scales is utilized to perform the stability analysis that shows the existence of instability associated with parametric resonances. This instability can be effectively stabilized by increasing the damping ratio of a disk.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1995년도 추계학술대회 논문집
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• pp.542-545
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• 1995

This paper provides an investigation of torque converter system using ERF (Electro-Rheological Fluid). The torque converter system using ERP is a new concepting device because we can change an apparent viscosity of ERF by adapting an electric field. The device was designed by using the equations which were proposed by Carlson et al. The devices based on ERF generally assume one two possible forms. One is the parallel plate type in which the device elements are facing circular disks separated by a flat layer of ERF, The other is coaxial cylinder or Couette types in which the ERF file the annular apace between a pair of coaxial cylindrical electrode. The discussion on this study is specifically for coaxial cylinder gemetry and experiment results show that the measured torque was rapidly increased with the increase of the eletric field.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2001년도 춘계학술대회논문집
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• pp.942-947
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• 2001

This paper provides a stability analysis of the transverse vibration of a spinning disk under the torque fluctuation from a permanent magnetic motor. An analytical model has been formulated for a flexible annular disk with its spinning velocity varying harmonically with the same frequency as the cogging torque. A perturbation method based on multiple time scales is applied to perform the stability analysis. Based on expressions for the amplitude and frequency of the parametric excitation, stability boundaries are determined in terms of a nominal spindle velocity, the least common multiple of poles and slots, the magnitude of torque fluctuation and the modal characteristics of. the disk. The stability diagrams predicted by perturbation have been verified numerically using the Floquet theory, which is in good agreement. In conclusion, the fluctuation in spinning velocity is found to affect the stability of the transverse vibration of a rotating disks. The results of this work can be applied to high precision spindle systems such as computer storage systems.