激光扫描混凝土裂缝的超声检测

为了探究激光扫描混凝土裂缝进行超声检测的可行性,采用激光扫描混凝土表面激发声场、表面波探头接收超声信号的方法,进行了相应的实验验证.通过对实验信号峰峰值和双极性特征分析,实现了混凝土表面裂缝的定位.同时采用有限元方法模拟了扫描激光在材料表面激发声场的过程,对超声信号进行了时域和频域上的分析.结果表明,当激光与裂缝边沿距离在1mm时,接收信号具有典型的双极性,且峰峰值达到极大值;当激光与裂缝边沿距离继续减小时,峰峰值迅速降低.通过扫描激光激发超声,在打点范围上形成由信号峰峰值表征的2维图像,由峰峰值突变特征和信号的双极性特征,可以实现混凝土表面缺陷边缘的定位.

Ultrasonic detection of concrete cracks by laser scanning

In order to explore the feasibility of ultrasonic detection of concrete cracks by laser scanning, sound field was excited by laser scanning concrete surfaces and ultrasonic signal was received with a surface wave probe. The corresponding experimental verification was carried out. The peak value and bipolarity of the experimental signal were analyzed. The location of concrete surface cracks was realized. At the same time, the finite element method was used to simulate the process of scanning laser exciting sound field on the material surface. Ultrasound signal was analyzed in time domain and frequency domain. The results show that, when the distance between laser and crack edge is 1mm, the received signals have typical bipolarity and the peak value reaches the maximum value. When the distance between laser and crack edge continues to decrease, the peak value decreases rapidly. Using the stimulated ultrasound by laser scanning, a 2-D image represented by the peak value of the signal is formed in the dot range. The characteristics of peak-peak mutation and signal bipolarity can locate the defect edge of concrete surfaces.