Enhancement of Selectivity in Nonlinear Ultrasonic Imaging of Closed Cracks Using Amplitude Difference Phased Array
Enhancement of Selectivity in Nonlinear Ultrasonic Imaging of Closed Cracks Using Amplitude Difference Phased Array
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DOI：
10.1143/jjap.51.07gb18
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发表时间：
2012-07
影响因子：
1.5
通讯作者：
Y. Ohara;Y. Shintaku;S. Horinouchi;M. Ikeuchi;K. Yamanaka
中科院分区：
文献类型：
--
作者：
Y. Ohara;Y. Shintaku;S. Horinouchi;M. Ikeuchi;K. Yamanaka
次谐波对闭合裂纹具有很高的选择性。然而，当使用短突发波达到高时间分辨率时，由于频率滤波中的泄漏，在次谐波图像中不仅会出现闭合裂纹，还会出现线性散射体。它们是降低亚谐波图像中闭合裂纹选择性的幽灵。在这里，我们提出了一种幅度差相控阵（ADPA），其中通过从大输入减去小输入乘以输入幅度比的次谐波图像来消除鬼影。基于双阻尼节点时域有限差分法（FDTD）对闭合裂纹亚谐波成像的二维仿真验证了ADPA方法。并在闭合裂纹试样中对ADPA方法进行了实验验证。
Subharmonic waves realize a high selectivity for closed cracks. However, when a short-burst wave is used to achieve a high temporal resolution, not only closed cracks but also linear scatterers appear in the subharmonic image owing to leakage in frequency filtering. They are ghosts that degrade the selectivity for closed crack in the subharmonic image. Here, we propose an amplitude difference phased array (ADPA), where the ghosts are eliminated by subtracting a subharmonic image at a small input multiplied by the input amplitude ratio from that at a large input. We verified the ADPA method by a two-dimensional simulation based on the finite difference time domain (FDTD) method with damped double nodes (DDNs) for subharmonic imaging of closed cracks. Furthermore, the ADPA method was experimentally verified in a closed-crack specimen.