基于超声Lamb波技术的储罐底板缺陷检测

 针对储油罐底板长期服役过程中罐底边缘板常发生腐蚀的情况,研发出一种超声Lamb波检测技术,开展了相关实验研究并设计了一套储罐检测自动化装置。对14mm大厚度钢板进行了仿真分析,计算出激发角度曲线,得出其A0模态Lamb波最佳激发角度为70°。设计加工了某2万m³成品油储罐底板1:1实验模型,并使用设计的UT350平板导波检测系统在该模型板上开展了实验,当激励信号频率为490kHz时检测结果最佳。实验结果表明Lamb波A0模态的低频脉冲信号能实现对大型钢板的缺陷检测,具有较好的缺陷识别能力。设计了一套能紧贴储油罐壁自动行走的储罐底板自动化检测装置,该装置可根据储罐边缘板自动调节传感器角度和压紧力,能根据检测效果调节行走速度。实现了对储罐底板缺陷连续、高效、稳定的在线检测过程。研究结果和设计装置实现了对储油罐底板缺陷检测,为储罐安全运行提供了保障。

Defect Detection for the Bottom Plate of Oil Tank Based on Ultrasonic Lamb Waves

Aiming at the situation that the bottom edge plates of oil tank often corrode in the process of long-term service, a kind of detection technology based on ultrasonic lamb wave had been developed. Relevant experimental study is carried out. The equipment for auto-testing tank is designed. Simulation analysis on the steel plate with the thickness of 14mm is conducted; the curve of excitation angle is calculated. The result is that for the lamb wave of A0 mode, optimum excitation angle is 70°. The experimental model with the ratio of one to one for refined oil tank bottom plate of 20000m³ is designed and processed. By using designed UT350 flat guided wave testing system, the experiment is developed on the model plate, the best test results is obtained while the excitation signal frequency is 490 kHz. The result of experiment indicates that low frequency pulse signal of A0 mode lamb wave is able to detect the defects of large-sized plates. The tank bottom automatically detection device that walks close to the storage tank wall is designed; the device is able to realize the continuous, high efficiency, and stability online detection process for the defect of oil tank bottom plate. The research results and designed device achieve the defect detection for the bottom plate of oil tank. The technique provides security for the safe operation of the storage tank.