Application Of Ultrasonic Method In Concrete Testing Based On Wavelet Analysis

Concrete material is indispensable in modern buildings,such as bridges,tunnels,and subsea construction projects.The durability of concrete materials is related to people's life and property safety and the steady development of national economy closely.Therefore,current concrete industries are mainly engaged in the testing of concrete materials quality.Non-destructive testing method plays an important role in the testing of concrete quality.Among them,the ultrasonic non-destructive testing method is widely used because of its convenient operation,high detection efficiency and harmless to the human body.The signal with noise gathers which using ultrasonic testing method.Therefore,using the method of wavelet time-frequency to analyze the signals can remove the noise and improve signal noise ratio effectively.In this paper,the ultrasonic pulse transmission method and wavelet analysis method are used in the non-destructive testing of concrete.The main work which has done is as follows:(1)The propagation characteristics of ultrasonic in concrete and the basic principle of ultrasonic pulse transmission method for detecting concrete are introduced in detail.Compared with other detection method,the pulse transmission method has the advantages of no blind area,no easy to missing detection and its attenuation is weak for single-thread transmission in concrete.So the ultrasonic pulse transmission method is chosen as the testing method of concrete high attenuation material.(2)Hardware circuit design and simulation of ultrasonic flaw testing system.Main hardware circuit design can be divided into two parts: The first part is the design of ultrasonic probe trigger circuit.It includes the selection of core devices and high-voltage module,working principle of whole circuit,design and simulation of the circuit.The other part is the design and simulation of signal processing circuit.In this paper,the signal processing circuit is divided into three parts: a signal amplification circuit,a full-wave rectification circuit,a low-pass filter circuit.(3)Multi-resolution analysis of ultrasonic testing signal.In order to analysis the collection of ultrasonic testing signals effectively,several common wavelet basic functions are used to analyze the ultrasonic testing signal,and comparing the results of the analysis with each other.It is concluded that the Sym8 wavelet function which is the most effective way to preserve the characteristic information of the ultrasonic testing signal.In this paper,the Sym8 wavelet is chosen as the wavelet basic function which is suitable for the ultrasonic testing signal processing.And on the basis of it,the optimal decomposition scale is 4.(4)Software design of ultrasonic flaw testing system.On the MATLAB software platform,using different threshold de-noising processing rules for noise reduction and make a comparison,Choose a threshold method which has the best de-noising effect.Using the wavelet threshold de-noising method to process ultrasonic testing signal could improve the signal noise ratio.It is helpful for the later work of defect identification.