Structural Acoustics

Structural acoustics is the study of the vibration and subsequent acoustic radiation from structures. Examples of such structures include models such as beams, plates, shells, as well as more realistic structures such as automobile components, airplane interiors, and submarine hulls.

Fuzzy Structures

Dr. Sparrow's current research in structural acoustics deals with a topic called fuzzy structures. Fuzzy structures are not related to fuzzy sets, a separate important area. Originally developed at ONERA in France by Christian Soize, fuzzy structures is the study of large dynamical systems, such as entire ships or airplanes, in which not all of the dynamical components can be described with certainty. A number of models for fuzzy structures now exist. Any of these fuzzy structures models can be straightforwardly included in conventional finite element representations for a structure.

The Soize fuzzy structures model assumes that a large number of probabilistic one degree of freedom oscillators are ''painted'' over an area of the structure that is well understood. Here is an example of the dynamical behavior of a normal one degree of freedom oscillator and an identical oscillator except in having uncertainty in its mass:



These are frequency response plots, impedance in Ns/m versus frequency in rad/s, for a one degree of freedom oscillator. The normal plot has no uncertainty, and the fuzzy plot has all parameters the same except for a plus or minus 20 percent uncertainty in the oscillator's mass. This research was undertaken in collaboration with Daniel A. Russell and Judith L. Rochat.

This research was funded by the Office of Naval Research.

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© 1995, 1996, Victor W. Sparrow.
Most recent update: 8/12/97
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