摘要
在各种无损检测方法中,超声回波法是探测钢筋混凝土结构最有潜力的方法之一.为了增加探测范围,一般使用比较低的超声频率进行探测,但是在对混凝土内部成像时,各种干扰信号的出现造成了低信噪比.合成孔径聚焦技术(SAFT)能够对反射信号进行有效聚焦,提高图像分辨力.由于激励波形频率低,时宽大,反射波包在聚焦过程中会产生很大的变形,影响了探测分辨力.因此引入了波包分解技术,能够将反射波包整体进行聚焦运算,克服了波包变形问题,能够更有效聚焦,提高混凝土探测成像的分辨力.此外,由于参与SAFT运算的点大量减少,可以提高成像运算速度.利用仿真实验对这种方法进行了验证,结果表明,这一方法的成像目标定位能力大大增强,能够获得更好的成像效果.
In Nondestructive Testing（NDT） field,ultrasonic inspection for Reinforced Concrete（RC） structures is one of the most promising ways.To increase the inspecting volume,low frequency Ultrasonic is generally employed to inspect the integrality and potential danger in the concrete structures.However,several kinds of disturbing signals result in the low signal-noise ratio in the concrete structures imaging.Synthetic Aperture Focusing Technique（SAFT） can focus effectively to reflected waves,and improve the reconstructed image＇s resolution through rough B-scan method.For low-frequency excitation signal,wavepacket distortion is produced during the focusing process,which decreases test resolution.Therefore,wavepacket decomposition technique,which can put the whole reflected wavepacket into focusing calculation,is introduced here to improve the reconstructed resolution.This technique solves the problem of wavepacket distortion,and better focusing effect and resolution are obtained.Furthermore,calculating velocity is increased because the points joined into SAFT calculation are cut down greatly.The presented technique has been verified by the simulation experiment.From the results,the method can improve more the ability of localizing object and give better imaging effect.
出处
《应用基础与工程科学学报》
EI
CSCD
2009年第6期943-949,共7页
Journal of Basic Science and Engineering
基金
国家自然科学基金资助项目(60477031)
国家自然科学基金重点项目(60535020)
南昌航空大学教育部无损检测重点实验室开放基金资助项目(ZD200929003)
南昌航空大学科研基金资助项目(EA200908019)
关键词
超声探测
混凝土
合成孔径聚焦
波包分解技术
ultrasonic inspection
concrete
SAFT
wavepacket decomposition technique
