Research And System Design Of Ultrasonic Testing Technology On Concrete Material Defects

Concrete is an inhomogeneous anisotropic medium, the transmission path of the ultrasonic wave is complex and the energy of the ultrasonic is attenuated seriously inside concrete. In the conventional concrete defect detection,only one-dimensional signal was processed according to the propagation time of echo signal, dominant frequency, and amplitude variation. This detection method was of low resolution and poor reliability. In the paper, a set of nondestructive testing system of ultrasonic transducer array is independently designed and developed on the basis of the existing concrete detection technology, which is used to study the high resolution imaging method of the concrete with probe array.In view of the low resolution defect of the low frequency ultrasound detection, a new synthetic aperture focusing imaging technique based on the probe array is proposed in this paper. This topic designed and developed a set of 4 channel concrete ultrasonic processing system, completed the emission of ultrasonic signal and the amplification, filtering of echo signal at the early stage. On the basis of further research on the USB2.0 protocol, we designed and developed a 4-channel data acquisition and control system based on USB2.0. According to the transmission command of the upper monitor, the control system can set various detection parameters for each channel, such as sampling model, sampling depth and gain size and so on, then collect the four echo signals processed in the preceding stage and save it to FIFO. An upper monitor interface which matched with the detection system is developed with using VC + +. Communicating with 4-channel data acquisition and control system by USB2.0, it can achieve the transmission of detection parameters, the acquisition and preservation of the echo signal.The system scans the concrete block through the probe arrays, using Matlab software to pre process the collected data, then the processed data is processed by synthetic aperture focusing imaging, the imaging results can basically reflect the defect location of the pre-buried square steel tube. The combination of the probe array and synthetic aperture focusing imaging algorithm proposed in this paper for the detection of concrete test block is feasible. The system can not only make intuitive judgments on the concrete defect, but also greatly improve the flaw detection resolution and detection accuracy of the detection system.