The complex envelope signal and an application to structural modal parameter estimation
✍ Scribed by Jae-Kab Lee; Youn Sik Park
- Publisher
- Elsevier Science
- Year
- 1994
- Tongue
- English
- Weight
- 421 KB
- Volume
- 8
- Category
- Article
- ISSN
- 0888-3270
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✦ Synopsis
Complex demodulation is a useful technique in fields such as communication, speech and seismic data processing. In this work, the complex demodulation technique is applied to the modal parameter estimation of mechanical systems. This method was developed for an efficient estimation of a dynamic system when impulse response measurements are truncated or estimating in the frequency domain is difficult. First, impulse responses of a structural system are measured in the time domain, then resonance frequencies are selected from its discrete Fourier transform. Next, the complex envelope of each mode is obtained by shifting the signal associated with the selected resonance frequency to zero frequency and filtering the remaining high frequency terms. When estimating the modal parameters from the obtained complex envelope of a specific mode, the so-called estimation and correction methods are used. A method of extracting parameters for a system having closely spaced modes is presented and discussed. The proposed method has been tested numerically and has many advantages over conventional frequency domain methods.