School of Mechanical Engineering, Beijing Institute of Technology, Beijing 100081, China; Key Laboratory of Fundamental Science for Advanced Machining, Beijing Institute of Technology, Beijing 100081, China.
Faculty of Materials and Manufacturing, Beijing University of Technology, Beijing 100124, China.
Ultrasonics. 2022 Sep;125:106788. doi: 10.1016/j.ultras.2022.106788. Epub 2022 Jun 8.
Longitudinal critically refracted (LCR) waves have already been widely applied for residual stress characterization. Such waves are usually generated using mode-conversion at the first critical angle of the incident longitudinal wave, which gives waves that then propagate at a dip-angle, and this places energy close to the surface of the specimen. The dip-angle needs to be minimized to improve both velocity measurement and residual stress characterization sensitivity. This paper reports a novel double-fold coil phased EMAT that can decrease the dip-angle. The performance of this new EMAT was investigated using both a COMSOL model and experiments. Initial model validation was provided through a comparison with experimental data. The EMAT design also enables scanning of samples, and operation in harsh environments where use of a PZT based transducer and couplants can complicate and limit inspection. The use of the EMAT has the potential to give more accurate time of flight (TOF) data and enhances the reliability and accuracy for residual stress measurement.
纵向临界折射（LCR）波已被广泛应用于残余应力特性描述。这种波通常是通过在入射纵波的第一临界角处的模式转换产生的，从而产生在倾斜角下传播的波，这将能量集中在试样表面附近。为了提高速度测量和残余应力特征描述的灵敏度，需要将倾斜角最小化。本文报道了一种新的双折叠线圈相控电磁超声换能器（EMAT），可以减小倾斜角。通过 COMSOL 模型和实验研究了这种新型 EMAT 的性能。通过与实验数据的比较，提供了初步的模型验证。EMAT 的设计还允许对样品进行扫描，并在恶劣的环境中运行，在这种环境中，使用基于 PZT 的换能器和耦合剂会使检测变得复杂和受限。EMAT 的使用有可能提供更准确的飞行时间（TOF）数据，并提高残余应力测量的可靠性和准确性。
