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首页> 外文学位 >Equilibrium and stability in spinning disk systems with application to computer hard disk drives, CD-ROMs, zip disks, and industrial circular saws.
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Equilibrium and stability in spinning disk systems with application to computer hard disk drives, CD-ROMs, zip disks, and industrial circular saws.

机译：旋转磁盘系统中的平衡性和稳定性，适用于计算机硬盘驱动器，CD-ROM，zip磁盘和工业圆锯。

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摘要

In this dissertation we address problems related to equilibrium and stability in spinning disk systems. The problems considered here are optimal profiles for spinning disks with respect to critical speed, multiple equilibria in hydrodynamically coupled disks rotating in an enclosure, and the dynamic stability of thin, warped rotating disks.; Chapter 2 presents thickness profiles for rotating disks that maximize critical speed. The disk thickness is permitted to vary between fixed lower and upper bounds, the lower bound corresponding to the minimum thickness saw capable of supporting the in-plane stresses associated with cutting forces and rotation, the upper bound corresponding to the thickness of the saw teeth. The optimal thickness profile consists of two annuli, the inner one with thickness equal to the upper bound, the outer one with thickness equal to the lower bound. With the optimal thickness profile, the critical speed can be raised up to 24%, depending on the clamping ratio of the disk and the lower bound. Optimal thickness profiles and increases in critical speeds are described and compared to existing saw designs.; In Chapter 3 experimental results are reported and a simple model proposed to explain a phenomenon in which the equilibrium deflection of a flexible disk rotating inside a narrow housing undergoes an abrupt jump when the rotation speed is varied slightly. Discontinuous jumps are observed in a small fraction (25%) of Zip disks rotating between 3000 rpm and 4500 rpm. For those disks exhibiting jumps, the jumps are repeatable for both increases and decreases in rotation speed during a test; no hysteresis is observed. A disk that initially exhibits the jump phenomenon may fail to exhibit jumps several days or weeks later and vice versa. Numerical results for a rotating membrane hydrodynamically coupled to the surrounding flow show that the number of possible equilibria is a sensitive function of the radial flows above and below the disk. In particular, a small change in radial flow from a radially inward flow to a radially outward flow can abruptly change the number of possible equilibria from two to one. The characteristics of this transition are compatible with the experimental observations.; In Chapter 4 non-linear, asymmetric equilibria of a thin rotating disk uniformly loaded by gravity and their stability are computed using the spectral collocation method. Stability boundaries as a function of rotation speed and loading magnitude are computed for uniform disks, eccentrically loaded disks, and for disks with an initial pre-warp. Experimental results aimed at corroborating these findings are presented but are inconclusive due to aerodynamically induced vibration of the disk. The experiments do indicate the presence of a backward traveling wave traveling at 1/4 of the disk rotation speed. The results presented provide quantitative guidelines for the influence of transverse loading on the stability of thin rotating disks.
机译：在本文中，我们解决了与旋转盘系统的平衡和稳定性有关的问题。这里考虑的问题是旋转盘在临界速度方面的最佳特性，在外壳中旋转的液力耦合盘的多重平衡以及弯曲的薄旋转盘的动态稳定性。第2章介绍了最大化临界速度的旋转磁盘的厚度曲线。允许盘的厚度在固定的上下限之间变化，该下限对应于能够支撑与切削力和旋转相关的平面内应力的最小厚度的锯，该上限对应于锯齿的厚度。最佳厚度轮廓由两个环组成，内部环的厚度等于上限，外部环的厚度等于下限。通过最佳的厚度轮廓，临界速度可以提高到24％，具体取决于磁盘的夹紧率和下限。描述了最佳的厚度曲线和临界速度的增加，并与现有的锯设计进行了比较。在第三章中，报告了实验结果，并提出了一个简单的模型来解释一种现象，即，当转速略有变化时，在狭窄的壳体内旋转的软盘的平衡挠度会突然跳变。在一小部分（25％）的Zip盘片（在3000 rpm和4500 rpm之间旋转）中观察到不连续的跳跃。对于那些表现出跳跃的磁盘，在测试过程中，旋转的增加和减少都是可以重复的。没有观察到磁滞。最初表现出跳跃现象的磁盘可能在几天或几周后无法呈现跳跃，反之亦然。水力耦合到周围流的旋转膜的数值结果表明，可能的平衡数是盘上方和下方的径向流的敏感函数。特别地，从径向向内的流动到径向向外的流动的径向流动的微小变化会突然将可能的平衡数从二变为一。这种转变的特征与实验观察结果是相容的。在第四章中，利用谱配点法计算了均匀受重力作用的薄转盘的非线性，不对称平衡及其稳定性。对于均匀磁盘，偏心加载的磁盘以及具有初始预翘曲的磁盘，计算了作为旋转速度和载荷大小的函数的稳定性边界。提出了旨在证实这些发现的实验结果，但由于磁盘的空气动力学引起的振动而没有定论。实验确实表明存在以磁盘转速的1/4传播的反向传播波。给出的结果为横向载荷对薄转盘稳定性的影响提供了定量指导。

著录项

  • 作者

    Warner, Grant Miller.;

  • 作者单位

    Columbia University.;

  • 授予单位 Columbia University.;
  • 学科 Engineering Mechanical.
  • 学位 Ph.D.
  • 年度 2003
  • 页码 96 p.
  • 总页数 96
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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