金属管件外检式电磁超声导波换能器电磁场量的解析计算式

电磁超声导波检测具有检测精度高、适合高温检测、无需耦合剂等优势,已成为无损检测领域中重要的检测技术。电磁超声导波检测的核心部件是电磁超声导波换能器。本文针对一种非铁磁性金属小径管外检式电磁超声导波换能器,基于扩展截断区域特征函数展开法(ETREE)分别推导偏置磁场奇对称、偶对称,暂态电磁场奇对称、偶对称及四种组合形式下(偏置磁场奇对称与暂态电磁场偶对称组合、偏置磁场奇对称与暂态电磁场奇对称组合、偏置磁场偶对称与暂态电磁场奇对称组合、偏置磁场偶对称与暂态电磁场偶对称组合)的电磁场量解析计算式。通过与有限元仿真结果进行对比,发现四种组合情况下解析计算式求解得到的洛伦兹力与有限元仿真(FEM)所得结果吻合,相对误差小于5%,且求解时间更短,验证了本文所提解析计算式的正确性及高效性。

管道超声导波检测技术研究进展

超声导波检测技术是一种通过分析导波在管道中的传播特性来检测管道损伤的无损检测技术,在无损检测领域具有重要意义,尤其在管道损伤检测中应用广泛。首先,简要介绍了超声导波及其检测技术的基本原理,重点介绍了导波的激励与接收、导波的频散和多模态特性,以及导波的衰减特性。其次,综述了超声导波换能器和超声导波信号处理技术的研究进展,其中,重点关注了压电换能器、磁致伸缩换能器和电磁声换能器的优化与设计,以及针对小缺陷信号的增强与识别和导波多模态分离的应对策略。最后,展望了超声导波技术在未来的发展方向。

超声导波任意波形激励技术研究

高效准确的无缝钢轨温度应力检测与探伤是确保高速铁路安全运营的重要技术手段,近年来,基于超声导波的钢轨应力检测技术受到越来越大的关注,精确控制钢轨中导波的波形是该技术的关键,但目前得到的接收波形精确度却不高。本文利用超声导波换能器和时间反转法,通过ANSYS有限元仿真分析,获得了任意波形的激励信号,提高了接收波形与理想波形的相关度。仿真结果表明,由时间反转法得到的接收波形精确度提高了约12%。

轨道伤损在线监测系统关键技术研究与实现

铁路与地铁承担着极其繁重的人员通行和货物运输任务,其运行封闭化,检修天窗期有限,工作环境恶劣,现有的管理、监控手段无法及时、全面地了解各关键部件的服役状态。文章提出了一种利用超声导波换能器向轨道内发射汉宁窗调制的特定频率脉冲信号,通过分析反射信号的等效特征,确定钢轨缺陷是否存在。经过多场景测试试验,验证该方法具有良好的效果。

Multi-belts coil longitudinal guided wave magnetostrictive transducer for ferromagnetic pipes testing

A new ultrasonic transducer with multi-belts coil for generating and receiving longitudinal guided wave in ferromagnetic material pipes is proposed.The theory backgrounds and transduction principle of the proposed transducer are presented and ana- lyzed.To verify the performance of the transducer,several experiments are performed.The performance of inspecting crack, frequency-tuned characteristic,effect of bias static magnetic field and dynamic magnetic field,lift-off effect and effect of the period number of the exciting current are investigated.The results show that the proposed coils not only could tune the center frequency but also could improve the amplitude and signal-to-noise(SNR)of the detected signals.Bias static magnetic field and dynamic magnetic field are two important factors influencing the amplitude of the longitudinal guided wave.The amplitude of the longitudinal guided wave is exponentially decreased versus the lift-off distance of the transmitter and receiver.Period number of excitation signal could influence the amplitude and wave width of the ultrasonic wave.The proposed transducer could easily control the wave modes and would be a better choice for pipes’monitoring and inspection compared to traditional single-belt coil transducer.