基于幅度补偿的混凝土合成孔径聚焦成像方法

SAFT Imaging Method for Concrete Blocks Based on Amplitude Compensation

合成孔径聚焦技术(Synthetic aperture focusing technique,SAFT)通过叠加邻近多道通的回波信息,可增强目标缺陷的信号特征,被广泛应用于超声无损检测领域。对于大深度混凝土结构的无损检测问题,由于超声波的衰减作用明显,传统B扫描及SAFT方法的成像效果均不理想。为提高混凝土超声成像的质量,测定了混凝土中超声波传播的相对衰减系数,引入幅度补偿技术对微弱回波信号进行幅度补偿,然后再对补偿信号进行SAFT成像处理,进一步增强了超声成像效果。人工混凝土块实验表明,本文所提方法比传统成像方法具有更高的成像分辨率,底部缺陷反射更加清晰,同时内嵌铁管及木块的实验均验证了本文方法的有效性。

Because of good property of superimposing the received signals from adjacent channels,the synthetic aperture focusing technique（SAFT）can further improve the signal characteristic of defects,which has been widely used in ultrasonic nondestructive testing（NDT）.For the concrete blocks embedded with defects in relatively deep position,it′s hard to obtain the high-resolution imaging results using the traditional B-Scan method and the traditional SAFT method because of the weak reflection information caused by heavy attenuation.In order to improve the ultrasonic imaging quality of concrete,the relative attenuation coefficient of ultrasonic propagating in concrete is measured,and the amplitude compensation technique is introduced to enhance the weal ultrasonic echo.Then the compensated signals are processed using the SAFT method,and the ultrasonic imaging quality can be further improved.Artificial concrete experiments show that the proposed method has higher imaging resolution than the traditional imaging methods,and the reflections of defects at the bottom area are clearer.The experimental results,including the embedded iron pipe and wooden block,verify the effectiveness of the proposed method.