Noncontact modal testing of hard-drive suspensions using ultrasound radiation force

Thomas M. Huber, Daniel Calhoun, Mostafa Fatemi, Randall R. Kinnick, James F. Greenleaf

Research output: Chapter in Book/Report/Conference proceedingConference contribution

7 Scopus citations


The head-gimbal assembly suspension is a cantilever-like structure that holds the heads on a hard drive. A noncontact method for modal testing, in air, of suspensions is discussed. This method utilizes the radiation force at the difference frequency generated by two intersecting ultrasound beams. The resulting low-frequency excitations were measured using a scanning vibrometer. This excitation technique has been demonstrated for MEMS and other small devices. There are several unique advantages of the ultrasound radiation force relative to mechanical shakers. Since the ultrasound radiation force is noncontact, a specialized test fixture was not needed; the technique was relatively insensitive to distracting resonances of fixtures and support structures. Another advantage is broadband excitation; a 550-kHz confocal ultrasound transducer excited suspension resonance frequencies from under 1 kHz to at least 50 kHz. Other advantages include the ability to selectively excite different modes. For example, the amplitude of one suspension's 5.0-kHz torsional mode was suppressed by an order of magnitude by shifting the modulation phase between the two ultrasound beams by 90 degrees. In another test, the amplitude of the 6.0-kHz torsional mode was doubled by moving the ultrasound focus point from near the center to near the edge of the suspension.

Original languageEnglish (US)
Title of host publicationIMAC-XXIV
Subtitle of host publicationConference and Exposition on Structural Dynamics - Looking Forward: Technologies for IMAC
StatePublished - 2006
Event24th Conference and Exposition on Structural Dynamics 2006, IMAC-XXIV - St Louis, MI, United States
Duration: Jan 30 2006Feb 2 2006

Publication series

NameConference Proceedings of the Society for Experimental Mechanics Series
ISSN (Print)2191-5644
ISSN (Electronic)2191-5652


Other24th Conference and Exposition on Structural Dynamics 2006, IMAC-XXIV
Country/TerritoryUnited States
CitySt Louis, MI

ASJC Scopus subject areas

  • General Engineering
  • Computational Mechanics
  • Mechanical Engineering


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