【摘要】 文章旨在用有限元法模拟LCR波的传播过程,初步探讨LCR波的传播机理。作者用有限元法模拟了LCR波在钢轨中传播的声场分布,并且对钢轨中LCR波的传播作了实验。用有限元法得到的接收楔块斜面所接收到的能量对时间的曲线与实验中接收楔块接收到的信号有较一致的结果:波形曲线趋势相同,在第一个波峰后都有第二个峰值。从有限元分析和实验结果得出结论:LCR波是纵波以第一临界角入射时产生的特殊模式,是一种特殊的头波,这与激发超声波的换能器和被测材料是有限尺寸的介质而不是无限大介质有关。更多还原

【Abstract】 The purpose of this article is to simulate the process of transmission of L_CR waves and carry out a preliminary study on the mechanism of transmission by finite-element method. The field distribution of an L_CR wave transmitted in rails is simulated, and experiments of L_CR wave transmission are conducted. It is found that the energy-time curve on an oblique plane of the receiving block obtained with finite-element method is similar to the signals measured in experiments. Their waveforms show the same tendency: the second peak coming after the first one. From both the finite-element analysis and the experiments, it can be concluded that the L_CR wave is a special head wave formed when a longitudinal wave is incident at the first critical angle. It is related to the finite-dimension rather than infinite-dimension of the media of the transducer generating ultrasonic waves as well as the material being measured.更多还原