基于多分辨率分析的砼内缺陷超声检测

利用多尺度小波变换方法，对经过混凝土内部缺陷的超声接收信号进行多分辨率分析。根据对在不同混凝土试件中传播的超声接收波的分析和实验结果，提出了一种新的能够表征混凝土内部缺陷的特征参数。

Ultrasonic Testing of Concrete Flaws Based on the Multi-resolution Analysis

Concrete is widely used in many construction proje cts. Concrete flaws refer to such inner defects as local l oosening or honeycombs or holes, which are caused by mold leaking or failing to tamp it at the time of construction. Concrete flaws existing in bridges or highways may cause a heavy loss to economy and life. Though non dest ructive detecting methods can provide a few parameters that indicate the existen ce of concrete flaws, they can't locate concrete flaws accurately. A new method , capable of both detection and analysis, is presented in this paper, which is t o use the wavelet analysis method to analyze the signals of concrete detecting. Traditional methods to analyze signals are based on Fourier analysis. However, it is known to all that with the Fourier analysis method, time domain informat ion and frequency domain knowledg e of given signals cannot be observed at the same time. But the wavelet analys is method can solve the problem above. When the wavelet method is applied to analyzing data derived from concrete detecting, it is found that when the ultrasonic passes through flaw areas its high freque ncy components are attenuated a lot, while the low frequency components are rel ativ ely less damped. Also conspicuous echoing and scattering will occur when high f requency components pass through concrete and meet considerable flaws. Therefore the signals will be deformed when all frequency components are added together a t the receiving end. Considering the characteristics of the ultrasonic passin g through concrete, a space component parameter U n is devised to indicate whether concrete flaws exist or not. Two groups of data gathered from concrete detecting have been analyzed and it is found that parameter U n is very effective in detecting concrete flaws.