Chen Weiwei, Lu Chao, Li Xiongbing, Shi Wenze, Zhou Yuxi, Liu Yuan, Zhang Shuzeng
School of Traffic & Transportation Engineering, Central South University, Changsha 410075, China.
Key Laboratory of Nondestructive Testing, Ministry of Education, Nanchang Hangkong University, Nanchang 330063, China.
Ultrasonics. 2024 Jul;141:107340. doi: 10.1016/j.ultras.2024.107340. Epub 2024 May 9.
In this paper we propose a novel ultrasonic longitudinal wave resonance method for measuring the thickness of metal walls using a laser-electromagnetic acoustic transducer (Laser-EMAT). The method is based on the surface constraint mechanism (SCM) of the material and is expected to be capable of accurately detecting local thinning of metal walls in a non-contact manner and at high temperatures. Based on finite element analysis of laser-EMAT ultrasonic resonance measurement of aluminum alloy thickness, we investigated the effects of such key factors as SCM, irradiation parameters of laser source, and the size of EMAT receiving coil on the accuracy of thickness measurement (resonance frequency position) and on the amplitude of the resonance wave. Both numerical simulations and experiments are conducted to demonstrate that the measurement accuracy of the proposed method is not affected by SCM, irradiation laser source parameters, and EMAT receiving coil size, and that accurate detection of stepped aluminum plates with thickness thinning from 3.0 mm to 0.5 mm is achieved. Furthermore, we were able to perform rapid detection of aluminum thin plate thickness at 500 °C temperature with an EMAT lift-off of 5.0 mm and achieved a relative experimental error as small as 3.40 %. The results obtained in this study showed that the proposed method performed well in non-contact measurement of metal thinning in harsh environment of high temperature.
在本文中，我们提出了一种新颖的超声纵波共振方法，用于使用激光电磁声换能器（Laser-EMAT）测量金属壁的厚度。该方法基于材料的表面约束机制（SCM），有望能够以非接触方式在高温下准确检测金属壁的局部变薄情况。基于对铝合金厚度的激光电磁声换能器超声共振测量的有限元分析，我们研究了诸如SCM、激光源的辐照参数以及电磁声换能器接收线圈的尺寸等关键因素对厚度测量精度（共振频率位置）和共振波幅度的影响。进行了数值模拟和实验，以证明所提出方法的测量精度不受SCM、辐照激光源参数和电磁声换能器接收线圈尺寸的影响，并且能够实现对厚度从3.0毫米减薄到0.5毫米的阶梯状铝板的准确检测。此外，我们能够在500°C温度下，电磁声换能器提离距离为5.0毫米时对铝薄板厚度进行快速检测，并且实现了低至3.40%的相对实验误差。本研究获得的结果表明，所提出的方法在高温恶劣环境下金属变薄的非接触测量中表现良好。
