弹性板中Lamb波在板端面的模态转换研究

摘要

The research on the condition that an incident sound wave excites the Lamb wave in underwater elastic plate and the mode conversion of the Lamb wave at the end of submerged elastic plate may become the basis for un-derwater target recognition. By the conversion solution for the mode equation of the elastic characteristic function, the energy reflecting coefficients of various modes of Lamb wave are solved when some mode of Lamb wave becomes incident into the end. The measurement experiment result on the scattering waves of the submerged elastic plate shows that, only when the incidence is applied at the critical angle of some mode of Lamb wave, this mode of Lamb wave may be directly excited in the elastic plate, while the other modes of Lamb waves are formed by reflection of this mode of Lamb wave at the end of the elastic plate. By the measurement and comparison for the sizes of leaky wave of various modes of Lamb wave in water, the theory on mode conversion and energy re-distribution at relevant ends are verified.%研究入射声波激励水下弹性板中Lamb波的条件以及弹性板中Lamb波在板端面处反射时模态转换问题可以成为水下目标识别的基础。通过对弹性体特征函数的模态等式进行变换求解得到某模态Lamb波入射到端面处时各模态Lamb波的能量反射系数。水下弹性板的散射波测量实验结果表明仅以某模态Lamb波的临界角入射时才能在板中直接激励出该模态Lamb波，板中其他模态Lamb波是由于该模态Lamb波在板的端面反射形成的；对各模态Lamb波在水中的漏波幅度测量比较，证实了有关端面处模态转换以及能量再分配的理论。