Development of Nonlinear Ultrasonic Phased Array for Evaluating Closed Cracks

概要

論文の詳細を見る
Although closed cracks can propagate under applied stress resulting in catastrophic accidents e.g. in atomic power plants, it is difficult to detect them since the intensity of scattering waves is much lower than that from open cracks. Recently, nonlinear ultrasound is expected to have a potential of detecting and evaluating them, and subharmonic wave with half-frequency of input signal is particularly useful because of its selectivity for cracks. Thus far, we have observed subharmonics in closed cracks and developed a model to analytically reproduce the observed waveform. However, a fast and reliable test was not realized due to the lack of imaging capability. In this study, we propose a novel nonlinear ultrasonic phased array to image closed and open cracks using digital signal processing for filtering at linear and nonlinear frequency. The nonlinear ultrasonic phased array is applied to well-defined fatigue crack. In addition, as a first step to ascertain the mechanism of subharmonic resonance, we examine the frequency dependence of subharmonic generation in closed cracks.
社団法人電子情報通信学会の論文
2005-09-23