Hard disk drives (HDD) not only offer an inexpensive way for data storage, but also enable various digital technologies ranging from computers to cloud computing. As HDDs increase their data density and spin speed, HDD vibration becomes more and more important. Excessive vibration of HDDs can not only cause read-write errors in operation, but also reduce yields in manufacturing processes (e.g., during servo writing).

Our research in the area of HDD vibration is world-class. In 1994, we first developed an accurate mathematical model to predict gyroscopic motion (also known as rocking modes or pitch modes) of a spinning disk pack supported by ball bearings in HDDs. The gyroscopic motion is particularly important to HDDs, because it is a major source leading to read-write errors. In late 1990, our research focused on vibration of HDD spindle motors with fluid-dynamic bearings (FDB). In early 2000, our study turned to coupled vibration among an HDD housing, a spinning disk pack, and connecting bearings. Our research encompasses mathematical modeling, numerical simulations, and experimental validation. These pioneering research results make us the world’s leading research team in HDD spindle vibration.

Since 1994, we have secured research funds from governmental agencies (e.g., National Science Foundation), disk drive companies (e.g., IBM, Seagate, Hitachi, and Western Digital) and spindle motor companies (e.g., NSK and Matsushita) to support the research efforts. Outcome of our research has been transferred to the disk drive industry via short courses and software licenses

Representative publications

1. I. Y. Shen and C. -P. Roger Ku, 1997: A Non-Classical Vibration Analysis of Multiple Rotating Disks/Shaft Assembly, ASME Journal of Applied Mechanics, Vol. 64, pp. 165-174.
2. H. Bittner and I. Y. Shen, 1999: Taming Disk/Spindle Vibrations through Aerodynamic Bearings and Acoustically Tuned-Mass Dampers, IEEE Transaction of Magnetics, Vol. 35, No. 2, March, pp. 827-832.
3. T. Jintanawa, I. Y. Shen, and K. Tanaka, 2001: Vibration Analysis of Fluid Bearing Spindles with Rotating-Shaft Design, IEEE Transaction on Magnetics, Vol. 37, No. 2, pp. 799-804.
4. C. W. Tseng, J. Y. Shen, and I. Y. Shen, 2003: Vibration of Rotating-Shaft HDD Spindle Motors with Flexible Stationary Parts. IEEE Transaction on Magnetics, Vol. 39, No. 2, pp. 794-799.
5. J. S. Park and I. Y. Shen, 2004: Aerodynamically and Structurally Coupled Vibration of Multiple Co-Rotating Disks. ASME Journal of Vibration and Acoustics, Vol. 126, pp. 220-228.
6. Tsung-Liang Wu, Chaw-Wu Tseng, Chen-Chi Lin, Shahab Hatam-Tabrizi, and I. Y. Shen, 2010: Effects of Stray Magnetic Forces on Position Error Signal During a Long Seeking-and-Settling Process, Microsystem Technologies: Micro- & Nanosystems and Information Storage and Processing Systems, Vol. 16, pp. 9-17.
7. I. Y. Shen, Liu Mengjun, Gao Feng, Lee Chong Wee, Lin Wuzhong, and Ong Eng Hong, 2013: Extraction of Bearing Coefficients of Fluid-Dynamic Bearing Spindle Motors Using a Proof Mass and a Hammer—A Refined Approach. IEEE Transaction of Magnetics, Vol. 40, pp. 2755-2761.