Enhancement of the spatiotemporal resolution of pulse-echo methods by digital filtering
In ultrasonic pulse-echo NDT of structures,the transducers usually operate in its harmonic frequencies in order to maximize the amplitude response.However,there exist some unwanted effects in such mode.For instance,the generated/detected signals will have long ringing,which means the spatiotemporal resolution will be reduced.Presented here is a digital filtering method to compensate the unwanted frequency response characteristics of transducers.The first step is to establish a discrete transfer function model of transducer system based on time-domain system identification algorithms.Then the established model can be realized by a digital compensation filter to reduce the ringing effects of the measured signals.Experimental verification of the proposed method is carried out.After calibrating and modelling for transducers by waterimmersion test,a compensation model is established and used to the thickness measurement of a concrete specimen.The compensation results show that the ring of transducer can be greatly reduced and the reflection from bottom of the specimen can be extracted from the original overlapped signals.To further validate the effect of the proposed method,its application in B-scan imaging of a concrete element with embedded anomaly is also given.
Ultrasonic test concrete digital filter transfer function system identification inverse system
Q.F. Li L.H. Shi D.K. Liang G. Li
Lab of Electromagnetics,Nanjing Engineering Institute,No.1 Haifuxiang,Nanjing,Jiangsu,China Nanjing University of Aeronautics and Astronautics,No.29 Yudao Street,Nanjing,Jiangsu,China
国际会议
The World Forum on Smart Materials and Smart Structures Technology(SMSST07)(2007年世界智能材料与智能结构技术论坛)
重庆·南京
英文
2007-05-01（万方平台首次上网日期，不代表论文的发表时间）