W. Z. Lin

Analysis of structurally transmitted vibration of HDD in notebook computer

Characteristics of structurally transmitted hard disk drive (HDD) vibrations induced by different built-in vibration sources, including speakers, fans and a CD/DVD drive in a notebook PC, are examined. It is found that at the high frequencies above 1000 Hz, the structurally transmitted HDD out-of-plane vibration is dominated by the vibrations induced by the speakers. The effects of the chassis design and HDD mounting on vibration transmission from speakers to HDD via chassis in the notebook PC are investigated. It is concluded that, in general, softer chassis and softer HDD mounting is helpful in suppressing the structurally transmitted vibrations of HDD at frequencies above 1000 Hz in a notebook PC. Furthermore, the HDD softer mounting modes should be kept away from the low order harmonics of the built-in fans and CD/DVD drive.

Analysis of Built-in Speaker-Induced Structural-Acoustic Vibration of Hard Disk Drives in Notebook PCs

This study is to develop a methodology and model to analyze the built-in speakers induced structural acoustic vibration of hard disk drive (HDD) in Notebook PC. First, a structural finite element (FE) model is built for the notebook PC to be analyzed using ANSYS. This FE model is subsequently verified by experiments. Second, the effects of acoustically transmitted and structurally transmitted oscillating forces, induced by the speakers, acting on the HDD, are investigated by acoustic FE model (SYSNOISE) and structural FE model. The acoustic transmission effect on the vibration of HDD is also investigated by experiment, which shows that the simulation results have a good agreement with experimental results. Finally, the effects of stiffness and damping ratio of the HDD supporters on the vibration of HDD are analyzed by the verified FE model.

Feasibility of Modeling Air Bearing as Linear Springs in Hard Disk Drive Dynamics Simulation

A model to predict the shock response of a 1.8-inch hard disk drive (HDD) is developed and validated by experiment. The head-actuator assembly (HAA), spindle disk and flexible base are included in the proposed model. The feasibility of modeling the air bearing as linear springs is investigated for HDD operating shock simulation. Result shows that as far as the vibration of the arm-suspension assembly is concerned, the air bearing between the disk and slider can be modeled by linear springs to speed up the simulation. However, if head/disk interface is concerned, the air bearing should not be modeled as linear springs in the studies of head-disk interface.

Modeling and prediction of structure-borne seek noise of HDDs

A numerical approach is presented for predicting the structure-borne seek noise in hard disk drives (HDDs) in time-domain. Rayleigh integral is adopted to relate the transient acceleration of top cover to its radiated sound pressure. A finite element modeling and simulation technique is employed to arrive at the transient vibration response, which is further used as the input for acoustic noise level calculation. The prediction results of a 1.8” HDD reveal the high dependency of structure-borne seek noise level on the current profile applied to VCM.

Feasibility of modeling air bearing as linear springs in hard disk drive

A model to predict the shock response of a 1.8-inch hard disk drive (HDD) is developed and verified by experiment. The feasibility of modeling the air bearing as linear springs is investigated. Result shows that when the vibration of the arm-suspension is concerned, the air bearing between the disk and slider can be modeled by linear springs to speed up the simulation.