摘要
为深入研究管道环焊缝缺陷特性,需要相控阵检测系统提供完全控制激励信号参数和获得接收回波信号的特性,针对该问题设计了32个模拟通道,可接入128个阵元,数字化频率达到125 Msample/s的相控阵超声检测系统。采用流水线式延时实现小数倍延时,脉冲发射延时精度为2.5 ns;使用Master-Slave结构的管理方式,在硬件上合理分配资源,对回波数据进行线性插值,同时根据脉冲的延时方案对各通道的插值数据进行存储,实现高精度数字波束形成。使用Hilbert变换提取形成波束在FIR滤波器滤波前后的包络,得到滤波后信噪比提高了9.4 d B。对标准试块进行缺陷检测实验,实验表明在深度上缺陷定位的相对误差为1.7%,相对于现有系统检测精度提高了接近2倍。
In order to deepen the study on features of girth weld defects of pipeline, full control of excitation signal parameters and access to the received echo-signals should be provided. A phased array ultrasonic testing system was designed with 32 analog channels, which can connect 128 elements and run at the condition of 125 Msample/s （Million Samples per Second ）digitalization frequency. Pipelined delay was adopted, which can realize fractional delay. The impulse transmission delay accuracy is 2.5 ns. Master-Slave management mode was used. Thus, the device can allocate resources reasonably, and high-precision digital beamforming can be realized by doing linear interpolation for echo data and saving the data after interpolating according to the delay scheme of pulse. Hilbert transform is adopted to extract envelopes of synthetic ultrasonic signal. After comparing signal to noise ratios（SNR） before and after filtering by FIR filter, it can be found that SNR after filtering is 9.4 dB higher. Moreover, a defect detection experiment was made toward the standard test block. The result shows that the defect position relative error in depth is 1.7% ,which is nearly twice as high as that of the existing system.
出处
《传感技术学报》
CAS
CSCD
北大核心
2017年第3期471-476,共6页
Chinese Journal of Sensors and Actuators
基金
国家自然科学基金项目(51375338)
