Abstract: The fundamental relation between structural vibration and acoustic radiation is discussed based on the theory of structure vibration modal analysis. An experiment is used for verification. The result of examination and analysis shows that frequencies of the peak value in sound signal power spectra are consistent with the structure modal frequencies. A new approach is presented for feature extraction from sound signals generated by the structure sound radiation in frequency domain using modal frequency. The approach was used to identify the loading pattern classification on the specific machine structure. The research result clearly expresses that the approach is reliable and effective for loading pattern classification. The approach is very useful for application on machinery operating state inspecting and fault diagnosis, because that the obtaining of the sound signal is easy and the cost is low as well as the method of measurement does not touching.

Key words: Feature extraction, Lane stacker structural, Loading pattern classification, Modal analysis, Sound radiation signal, Vibration acoustic transfer characteristic