Research On Ultrasonic Arrays Imaging Algorithm About Concrete Internal Abnormal

As China enters a rapid development stage, the building, transportation, water conservancy and other public facilities are developing completely. The concrete has been used widely, because of its advantage of steadiness, durability, low price. The construction of safety should always be put in the most important place. However, the traditional concrete detection mainly depends on the detection of engineers who test a small scale of sampling concrete, which is difficult to ensure the accuracy of detection.The nondestructive techniques are helpful to evaluate the stability of concrete and contributive to the inspection of its quality. The purpose of the paper is to study the detection ability of ultrasonic array imaging for the abnormal defects inside the concrete.Concrete is a kind of multiphase and composite system of material, in which various mediums and defect interfaces are distributed widely. So the ultrasonic propagation has a serious and complex scattering in concrete. Time-reversal is based on wave propagation reciprocity and its focusing is adaptive and has loss compensative ability at defect. Therefore, the method can be applied to concrete and other heterogeneous mediums. So the paper uses the time-reversal method to detect the defects inside the concrete.Although the time-reversal method can make the signal focus, it is difficult to reverse loading time-reversal signal, because of the low signal-to-noise ratio. So the paper proposes an enhanced method based on time-reversal. It does not require real time-reversal loading and can improve the signal-to-noise ratio, and it has the time-reversal focusing effect.Firstly, the paper uses the Abaqus software to establish concrete and defect model on which a pulse signal is inspired and the array sensors receive echo signals. With the improvement of the time-reversal method on Matlab to process these signals, the signal-to-noise ratio is improved. Intercepting effective signal inside the echo signal,including defect signals and then to generate imaging. Finally, a more precise defect imaging is dealt with by the ultrasonic array imaging method. Then for the accuracy of the theoretical method, a concrete block is tested and the same way to deal with echo signals that is from the experiment enhances the positioning of the imaging effect. Theresults of simulation and experiment show that the method has a certain effect on defect location.This topic based on the characteristics of the ultrasonic transmission in concrete, is to improve the detective efficiency of concrete with the improved calculation method of the time-reversal and algorithms of array imaging. The project takes a series of research including the Abaqus software model simulation, fusion of array signal detection, array data imaging and the experiment. And the topic uses mathematical software Matlab and finite element software Abaqus algorithm program debugging and simulation to debug program and simulate model.