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中文核心期刊

北极冰层反射系数与Lamb波频散的关系

Relationship between the reflection coefficient of Arctic ice and dispersion of Lamb waves

  • 摘要: 为获得北极冰层反射系数与Lamb波的关系, 应用传递矩阵法分析了冰层反射系数实虚部、模值范围与冰层自由Lamb波、漏Lamb波频散的关系。获得了冰层自由Lamb波频散曲线与反射系数的对应关系; 针对漏Lamb波相速度大于冰层纵波声速, 振动模态无法识别的现象, 通过调整冰−水界面耦合条件, 得到改进后的漏Lamb波频散方程, 获得小角度入射时冰层漏Lamb波振动模态与反射系数的关系, 并结合北极跨冰层检波实验数据进行了验证。结果表明, 反射系数小于1的频段声波激发了相应频段的冰层Lamb波。此外, 根据改进的漏Lamb波频散方程进一步获得了多层冰层漏Lamb波频散曲线。

     

    Abstract: To obtain the relationship between the reflection coefficients of the Arctic ice layer and Lamb waves, the transfer matrix method is applied, and the real and imaginary parts, modulus range and dispersion of the free Lamb waves and leaky Lamb waves are analyzed. The corresponding relationship between the dispersion curves of the free Lamb waves in the ice layer and the reflection coefficients is obtained. In response to the phenomenon that the vibration mode of the leaky Lamb wave cannot be identified when the phase velocity of the leaky Lamb wave is greater than the longitudinal wave velocity of the ice layer, the improved dispersion equation of the leaky Lamb wave is obtained by adjusting the coupling conditions of the ice water interface. The relationship between the vibration mode and reflection coefficient of the leaky Lamb wave in the ice layer under small angle incidence is obtained, and verified by the data from the cross-ice detection experiment in the Arctic. The results indicate that acoustic waves in the frequency band with reflection coefficients less than 1 excite the Lamb waves in the corresponding frequency band of the ice layer. In addition, based on the improved leaky Lamb wave dispersion equation, the dispersion curves of multi-layer ice layer leaky Lamb waves are further obtained.

     

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