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Surface Friction Guiding For Reduced High-Frequency Lateral Vibration Of Moving Media, V. Kartik, Jonathan A. Wickert
Surface Friction Guiding For Reduced High-Frequency Lateral Vibration Of Moving Media, V. Kartik, Jonathan A. Wickert
Jonathan A. Wickert
The free and forced vibration of a moving medium is examined in an application where distributed friction guiding is used to control lateral position passively. Subambient pressure features formed in the guides intentionally modify the naturally occurring self-pressurized air bearing and increase the contact force between the medium and the guide's surface. These features increase friction to a level beyond that achievable based on the nominal wrap pressure. The moving medium is modeled as a beam that is transported over frictional regions and subjected to prescribed boundary disturbances arising from runout of a supply or take-up roll. For axial transport …
Optimizing Vibration Isolation Of Flex Circuits In Hard Disk Drives, M. R. Brake, Jonathan A. Wickert
Optimizing Vibration Isolation Of Flex Circuits In Hard Disk Drives, M. R. Brake, Jonathan A. Wickert
Jonathan A. Wickert
A "flex circuit" is a laminate of polyimide substrate, adhesive, and copper conductors that is used to connect the stationary electronic components in a computer hard disk drive to the rotating arm that positions read/write heads above the disks. The flex circuit's transverse and longitudinal vibrations couple with the arm, and those motions, although seemingly small, degrade performance during seek operations from one data track to another. The flex circuit and arm mechanism is defined by a number of geometric parameters, and some latitude is available at the design stage for choosing dimensions and angles so as to minimize vibration …
Vibration Of Flex Circuits In Hard Disk Drives, Jonathan A. Wickert
Vibration Of Flex Circuits In Hard Disk Drives, Jonathan A. Wickert
Jonathan A. Wickert
A flex circuit connects the stationary electronic components in a hard disk drive to the rotating arm that carries the read/write heads and positions them above data tracks on the disk. Flex circuits are conventionally formed as a laminate of polyimide substrate, adhesive, and copper conductors. Deformation of a flex circuit is discussed in the context of the following stages: the initial unstressed shape, configurations in which stresses set and relax in response to elevated temperature, equilibrium, and small amplitude vibration. The model involves displacements of the flex circuit in the directions tangent and normal to the local equilibrium shape, …
Spatial Modulation Of Repeated Vibration Modes In Rotationally Periodic Structures, M. Kim, J. Moon, Jonathan A. Wickert
Spatial Modulation Of Repeated Vibration Modes In Rotationally Periodic Structures, M. Kim, J. Moon, Jonathan A. Wickert
Jonathan A. Wickert
When a structure deviates from axisymmetry because of circumferentially varying model features, significant changes can occur to its natural frequencies and modes, particularly for the doublet modes that have non-zero nodal diameters and repeated natural frequencies in the limit of axisymmetry. Of technical interest are configurations in which inertia, dissipation, stiffness, or domain features are evenly distributed around the structure. Aside from the well-studied phenomenon of eigenvalue splitting, whereby the natural frequencies of certain doublets split into distinct values, modes of the axisymmetric structure that are precisely harmonic become contaminated with certain additional wavenumbers. From analytical, numerical, and experimental perspectives, …