VIBRATION AND NOISE ANALYSIS OF COMPUTER HARD DISK DRIVES

Size: px

Start display at page:

Download "VIBRATION AND NOISE ANALYSIS OF COMPUTER HARD DISK DRIVES"

Alicia York
7 years ago
Views:

1 VIBRATION AND NOISE ANALYSIS OF COMPUTER HARD DISK DRIVES A dissertation Submitted in partial fulfillment Of the requirement for the degree of MASTER OF TECHNOLOGY in DESIGN OF MECHANICAL EQUIPMENT by V.VIJAYA PRAKASA RAO (2002 MED 024) Under the guidance of Prof.V.P.AGRAWAL and Dr. N.TANDON DEPARTMENT OF MECHANICAL ENGINEERING INDIAN INSTITUTE OF TECHNOLOGY DELHI MAY 2004

2 CERTIFICATE This is to certify that the thesis entitled Vibration and Noise analysis of Computer Hard Disk Drives being submitted by V.VIJAVA PRAKASA RAO to the Mechanical Engineering Department of Indian Institute of Technology Delhi for the award of the degree of Master of Technology in Design of Mechanical Equipment is a record of bonafide work carried out by him under our supervision and full filled all the requirements for the submission of the thesis, which to our knowledge has reached the require standard. The results obtained in this thesis have not been submitted in part or in full, to any other University or Institute for the award of any Degree or Diploma. Prof. V.P.Agrawal Professor, Department of Mechanical Engineering, Indian Institute of Technology, New Delhi Dr. N. Tandon Associate professor, Industrial Tribology, Machine Dynamics & Maintenance Engineering Center, (ITMMEC) Indian Institute of Technology, New Delhi

3 Dedicated to my parents ii

4 ACKNOWLEDGEMENT I have a great pleasure in expressing my indebtedness to my supervisors Prof. V.P.Agrawal and Dr. N. Tandon for their invaluable guidance and encouragement extended to me, with out which the present work would not have been successful. I wish to express my sincere thank to Prof. T.K.Kundra for his indispensable suggestions during the experimentation. I would like to thank the dynamics lab in charge Mr. Ashok Kumar for the help that he provided during my experiments. I take this opportunity to thank all my friends for their help and moral support. At last but not least, I would like to extend my wholehearted sense of gratitude to my family members, for all the love they showered me, with their desire to see me in a good position has been the prime motivation for me. Date: V. Vijaya Prakasa Rao iii

5 ABSTRACT Vibrations of computer hard disk drive have become an important concern with their increasing track density and speed. These increases are required for higher disk capacity and reduced seek time. Excessive vibrations can result in track misregistration and even disk crash. High noise is disturbing for concentration on computer job. Vibration and noise generated by some computer hard disk drives of different speeds have been analyzed. The vibration natural frequencies of disk platter were computed theoretically and by FEM. These were also verified experimentally by modal testing. The first four natural frequencies of disk platters measured experimentally were 359,525,650 and 1080 Hz. The overall vibration amplitude of rotating disk platters was also measured with the help of capacitance type of probe. Sound power levels of hard disk drives were determined in seek and idle modes. The contribution of noise produced by different sources with in the drives to total noise was assessed to find major noise sources. The measurement results showed that the major noise source in lower speed hard disk drive was the actuator arm fly over the platter where as in the case of higher speed drives; the main source was the disk platter air flutter noise. A-weighted noise generated by the hard disk drives was mainly in the frequency range of 2 to 8 khz. Hard disk drive head crash analysis was carried out to identify the acceleration levels of actuator arm by increasing the surface contact between platter and actuator arm head. HDD platter head crash was analyzed experimentally. Actuator arm contact with platter is increased intentionally by placing the tiny weights over the arm. The vibration velocity of actuator arm increased as the surface contact between head and platter increases. Key words: HDD, Platter vibrations, Major noise source, Actuator arm crash iv

6 INDEX Certificate Acknowledgement Abstract Index List of Figures List of Tables Nomenclature i iii iv v vii ix x Chapter 1 introduction A Brief history of the hard disk drive Early Hard disk drives Constructions and operation of the hard disk Construction of HDD Hard disk operational overview Importance of noise and vibrations in PC Acoustic noise in HDD Vibrations in HDD HDDs used in the study Objectives 10 Chapter 2 literature review Vibration Issues Noise issues Literature on HDD head crash analysis 13 Chapter 3 Dynamic analysis of HDD platters Theoretical analyses FEM analysis Modal testing Applications Experimental setup 22 v

7 Chapter 4 Online Vibration Measurements of HDD Operating principal Experimental setup Experimental procedure Results 27 Chapter 5 HDD Noise Source Identification Introduction Methodology Measurement of sound pressure level Calculation of surface sound pressure levels Calculation of sound power level Procedure for estimation of sound power Instruments used Sound power levels One-third-octave noise spectrum /3 rd octave noise spectrum plots of HDD Noise control options of hard disk drive 49 Chapter 6 HDD crash analysis Introductions Experimental procedure Procedure Experimental Results Vibration velocity spectrums of actuator arm 56 Chapter 7 Conclusions and Remarks Chapter 8 Suggestions for future work 63 References 64 vi

MODELLING AND ANALYSIS OF INTEGRATED PRODUCTION - INVENTORY - DISTRIBUTION SYSTEMS. A. NOORUL HAQ Department of Mechanical Engineering

MODELLING AND ANALYSIS OF INTEGRATED PRODUCTION - INVENTORY - DISTRIBUTION SYSTEMS 0 00 By A. NOORUL HAQ Department of Mechanical Engineering z-l1l2 THESIS SUBMITTED IN FULFILMENT OF THE REQUIREMENTS FOR