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Inverse Method for Estimating the Wave Propagation Parameters of Two Dissimilar Wave Types

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Patent application, Filed 6 Aug 2004

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A method is provided to distinguish two blended but different waves in a structure, such as compression and shear waves, by measuring their corresponding wave numbers and wave speeds. Other characteristics of the two waves may also be measured, such as the propagation coefficients of both waves. All measurements can be calculated at every frequency for which a transfer function measurement is made. The measurements do not depend on the resonance frequencies of the structure and do not require curve fitting to the transfer functions. The present invention relates generally to determining wave propagation parameters and, more particularly, to determining wave propagation parameters of two dissimilar wave types that have been blended together. Measuring the wave propagation parameters of structures is important because these parameters significantly contribute to the static and dynamic response of the structures. Because most measurement methods are designed to isolate and measure one specific wave, they fail to correctly analyze dual wave propagation. The present method preferably uses seven transfer functions that are obtained by vibrating the structure in a method that excites two different types of wave motion. Measurements may be made of either strain, displacement, velocity, or acceleration of the structure. Once this is accomplished, the seven measurements are combined to yield a closed form solution of both wave numbers and wave speeds. The four corresponding wave propagation coefficients also are estimated with a closed form solution during this process. Once these six parameters are known, the system response can be correctly characterized. 16 figures

Subject Categories:

  • Numerical Mathematics
  • Fluid Mechanics
  • Mechanics

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