Date of Award

2017

Document Type

Open Access Master's Report

Degree Name

Master of Science in Mechanical Engineering (MS)

Administrative Home Department

Department of Mechanical Engineering-Engineering Mechanics

Advisor 1

Andrew R. Barnard

Committee Member 1

Charles D. Van Karsen

Committee Member 2

Jason R. Blough

Abstract

Digital information stored in rotational media, such as Hard Disk Drives (HDD) needs to be reliable and readily accessible. Various studies have been performed on the modal analysis of HDDs and the noise emitted during operation. Analysis performed by Siemens Corporation, IBM and Tyco Fire Protection Products show that HDDs are sensitive to noise. This report initially focusses on identifying the critical frequency ranges and the levels of noise where the performance of the drives reduces. A series of tests have been performed using pink noise at one-third octave frequency bands at sound pressure levels ranging from 80 dB to 130 dB (re 20 µPa) in an anechoic chamber. A detailed description on the test set-up along with the methodology of testing has been provided. Read/write speeds have been used to measure HDD performance. A completely random read/write workload with varied data packet size has been incorporated through a custom LabVIEW program. Serial Advanced Technology Attachment (SATA) drives have been used for the analysis. General trends in performance curves of Enterprise HDD, Laptop drives, Helium filled HDD and Non-Helium filled HDDs are shown. HDD performance is shown to be sensitive to sound pressure levels as low as 85 dB (re 20 µPa) at some frequencies. Depending on the type of the HDD, noise at a frequency range of 2 kHz – 8 kHz beyond certain SPL affect the HDD’s performance up to the point of temporary and even permanent failure. Speculating the observed frequency content to be the resonant frequencies of the internal parts such as the platter and head gimbal assembly, the modal analysis has been performed. The report later focusses on impact test and measurement of the response using non-contact methods on the HDDs platter and head gimbal assembly. A detailed analysis on the test set-up and measurement parameters has been laid out. The modal parameters obtained, provide an insight to the causal for the HDD’s performance reduction and help establish a relation with the results obtained from acoustic experiments. The modal parameters and the response obtained has been validated using Finite Element Analysis. A comprehensive analysis on the failure of HDDs due to modal parameters has been presented.

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