Title: Application of Bispectral Analysis to Estimate Nonlinear Acoustic Parameter
Abstract: The fact that material degradation can be evaluated by measuring nonlinear acoustic effect has been proposed by previous studies. The most conventional method to measure nonlinear acoustic effect is to measure the absolute magnitude of fundamental and order harmonic frequency component in the propagated ultrasonic wave. For this aim, power spectral analysis technique has been used widely. However, the power spectral analysis has fatal disadvantage that the gaussian additive noise superimposed in the wave signal remains in the power spectrum domain. Moreover, the magnitude of order harmonic frequency component generated by nonlinear effect is so small that it may be suppressed by the noise remained in the power spectrum. In order to overcome this problem, this paper proposes an alternative method using bispectrum analysis, which can reduce the effect of addictive gaussian noise and. the nonlinear parameter can be obtained more stably. Simulations showed that the proposed method can obtain the value of nonlinear parameter near to the true value in the case of low SNR signal. Also, in order to confirm the usefulness of our method in actual case, we compared the nonlinear parameter obtained by using both of power spectral and bispectral analysis for several specimen intentionally degraded by fatigue load.
Publication Year: 1999
Publication Date: 1999-01-01
Language: en
Type: article
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