Application of a pure moment exciter for measurement of moment-rotational DOF frequency response functions

Martin Wesley Trethewey, Henry Joseph Sommer, III

Research output: Contribution to journalConference articlepeer-review


A variety of experimental methods to measure rotational responses of structures have evolved. Most applications have measured frequency response functions between a translational excitation and the corresponding rotational response. The measurement of the rotational response to a moment excitation has mostly been ignored, due to the difficulty of applying a moment excitation to the test system. The work in this paper introduces a technique that can produce a pure time varying moment, without a translational force, to a structure. The technique utilizes a set of geared eccentric masses, driven by a DC motor. The theory behind the design is first described. Then, a series of tests are performed to determine the capabilities of the pure moment exciter. The results show the analytical predictions are within 5% of the experimental values. The pure moment shaker is then applied to a laboratory test structure to measure the rotational degree of freedom with a moment excitation. The paper concludes with a discussion and assessment of the ability of the technique to effectively measure moment-rotational frequency response functions.

Original languageEnglish (US)
Pages (from-to)1153-1158
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
Volume4753 II
StatePublished - Jan 1 2002
EventProceedings of IMAC-XX: A Conference on Structural Dynamics - Los Angeles, CA, United States
Duration: Feb 4 2002Feb 7 2002

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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