電磁超音波センサによる軟鋼ワイヤのロングレンジ探傷

概要

論文の詳細を見る
Frequency dependence of group velocity is measured for longitudinal wave propagating along length of a steel wire. In a long ranged inspection of steel wires by using a broadband pulse, flaw detectability is greatly lowered by the waveform distortion due to geometric dispersion. To improve the flaw detectability, effective compensation for the dispersion should be carried out, which requires an accurate measurement of the dispersion curve. In this study, we suggest to use digital frequency filters to evaluate the frequency dependence of group velocity, which can then be translated into the dispersion curve of phase velocity. The group velocity can be determined as the velocity of the envelope of narrowband wavelet composed by filtering. Accuracy of the method was first examined by using the waveform simulated with given dispersion curve. We then applied this method to the echoes from artificial flaws and found that the signal to noise ratio is improved.
社団法人日本機械学会の論文
1999-12-25