电磁超声兰姆波模态能量密度分布特征研究

针对钢板中兰姆波传播机理复杂性和多模态特性导致回波信号识别难的问题,建立热力学第一定律求解钢板中能量密度分布模型,对钢板中微体元的力密度、振动位移和能量密度分布的相关性进行理论分析和数值计算。研究了钢板中电磁超声兰姆波模态与能量密度分布的关系,并对能量密度分布特征进行实验研究。结果表明:电磁超声兰姆波频厚积增大,钢板微体元中各兰姆波模态振动位移增大,振动能量增加;通过兰姆波多模态的能量强度、能量速度研究回波信号能量密度分布特征,证明兰姆波多模态具有可量化的能量密度分布特征信息,为基于能量密度的电磁超声兰姆波量化检测提供理论依据。

Research on the distribution of energy density of modal identification of electromagnetic ultrasonic lamb wave propagation

Because the echo signal caused by the plate Lamb wave multi modal characteristics is difficult to be identified, the complexity of mechanism of propagation of Lamb wave is addressed and the topology of steel micro element model by using the First Law of Thermodynamics is established to solve the distribution of energy density. The correlation of force density, vibration displacement and energy density distribution is theoretically and numerically analyzed. The relationship of the plate Lamb wave of propagation characteristics, the Lamb wave modes and the distribution of energy density is investigated, and the experiment of the modal energy density distribution is carried out. Results show that with the excitation frequency of electromagnetic ultrasonic Lamb wave increasing, the micro element modal vibration displacement increases, and the ultrasonic vibration energy increases. The echo signal of energy density distribution is studied by Lamb wave multi modal energy intensity, and it can be proved that Lamb wave multi modal energy density distribution includes quantifiable information of energy density distribution. The distribution of energy density in wave group signal can provide a theoretical foundation for the quantitative detection.