Investigation On Fast Reconstructing Reflection Coefficient From Big Acoustic Material Samples By NAH

The reconstruction of reflection coefficients using Near-field Acoustic Holography is based on the theory of wave acoustics. Many achievements have already been made in the research on Acoustic Holography, but so far the work amount of the methods measuring reflection coefficients is rather huge and time consuming. So it is useful to find a fast method of reconstructing reflection coefficients.Based on the basic theory of Acoustic Holography in axis-symmetric sound field, a theoretical model of fast reconstructing reflection coefficients is built in this thesis. According to this theoretical model, only complex pressures of radius direction on each two parallel planes are needed to reconstruct reflection coefficients, which greatly reduce the amount of work.A systematic, theoretical simulation research on this theoretical model has been done in this thesis. Influences of different factors on reflection coefficients are also analyzed. A testing experiment using elastic steel plate with given theoretical reflection coefficients is done, and the result matches the theoretical value well. The experimental result shows that this technology of reflection coefficients reconstruction can reconstruct material's reflection coefficients precisely. In addition, it costs much less time. To sum up, it is a technology of high feasibility and practicability.