Accession Number : ADA269225

Title :   Active Control of Acoustic Pressure Fields Using Smart Material Technologies.

Descriptive Note : Contractor rept.,

Corporate Author : INSTITUTE FOR COMPUTER APPLICATIONS IN SCIENCE AND ENGINEERING HAMPTON VA

Personal Author(s) : Banks, H. T. ; Smith, R. C.

Report Date : JUN 1993

Pagination or Media Count : 30

Abstract : An overview describing the use of piezoceramic patches in reducing noise in a structural acoustics setting is presented. The passive and active contributions due to patches which are bonded to an Euler-Bernoulli beam or thin shell are briefly discussed and the results are incorporated into a 2-D structural acoustics model. In this model, an exterior noise source causes structural vibrations which in turn lead to interior noise as a result of nonlinear fluid/structure coupling mechanisms. Interior sound pressure levels are reduced via patches bonded to the flexible boundary (a beam in this case) which generate pure bending moments when an out-of-phase voltage is applied. Well-posedness results for the infinite dimensional system are discussed and a Galerkin scheme for approximating the system dynamics is outlined. Control is implemented by using LQR optimal control theory to calculate gains for the linearized system and then feeding these gains back into the nonlinear system of interest. The effectiveness of this strategy for this problem is illustrated in an example. Active noise control, Piezoceramic patches, LQR Optimal control theory.

Descriptors :   *CERAMIC MATERIALS, *PIEZOELECTRIC MATERIALS, *NOISE REDUCTION, ACOUSTICS, BENDING, BENDING MOMENTS, BOUNDARIES, CONTROL, CONTROL THEORY, COUPLINGS, DYNAMICS, FLUIDS, MODELS, NOISE, NONLINEAR SYSTEMS, PHASE, SOUND, SOUND PRESSURE, STRATEGY, STRUCTURES, THEORY, VIBRATION, VOLTAGE, BEAMS(STRUCTURAL), SHELLS(STRUCTURAL FORMS), DAMPING.

Subject Categories : Acoustics
      Mechanics
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE