Zhang Hui, Zhang Haiyan, Zhang Jiayan, Liu Jianquan, Zhu Wenfa, Fan Guopeng, Zhu Qi
School Institute for Advanced Communication and Data Science, School of Communication and Information Engineering, Shanghai University, Shanghai 200444, China.
School of Urban Railway Transportation, Shanghai University of Engineering Science, Shanghai 201620, China.
Sensors (Basel). 2019 Aug 29;19(17):3744. doi: 10.3390/s19173744.
Wavenumber imaging with Green's function reconstruction of ultrasonic diffuse fields is used to realize fast imaging of near-surface defects in rails. Ultrasonic phased array has been widely used in industries because of its high sensitivity and strong flexibility. However, the directly measured signal is always complicated by noise caused by physical limitations of the acquisition system. To overcome this problem, the cross-correlations of the diffuse field signals captured by the probe are performed to reconstruct the Green's function. These reconstructed signals can restore the early time information from the noise. Experiments were conducted on rails with near-surface defects. The results confirm the effectiveness of the cross-correlation method to reconstruct the Green's function for the detection of near-surface defects. Different kinds of ultrasonic phased array probes were applied to collect experimental data on the surface of the rails. The Green's function recovery is related to the number of phased array elements and the excitation frequency. In addition, the duration and starting time of the time-windowed diffuse signals were explored in order to achieve high-quality defect images.
利用格林函数重建超声散射场的波数成像技术来实现铁轨近表面缺陷的快速成像。超声相控阵因其高灵敏度和强灵活性而在工业中得到广泛应用。然而，直接测量的信号总是受到采集系统物理限制所导致的噪声干扰。为克服这一问题，对探头采集的散射场信号进行互相关运算以重建格林函数。这些重建信号能够从噪声中恢复早期信息。在具有近表面缺陷的铁轨上进行了实验。结果证实了互相关方法重建格林函数用于检测近表面缺陷的有效性。应用不同类型的超声相控阵探头在铁轨表面采集实验数据。格林函数的恢复与相控阵元件数量和激励频率有关。此外，还探讨了加窗散射信号的持续时间和起始时间，以获得高质量的缺陷图像。
