提出了用低频多模式超声兰姆波定征方法来估计超薄弹性层的纵波声速、横波声速、厚度和密度等参数。这里“超薄”是指材料厚度 h 远小于材料中的声波波长λ,由此导致在时域上材料前后界面的各次回波信号相互混迭。文中采用水浸耦合方式,结合空间波场设计和泄漏兰姆波频域分析方法获取了材料零阶对称与反对称模式兰姆波色散曲线,并以色散特性为基础的零阶对称模式兰姆波定征方法、简化方法、零阶反对称模式兰姆波定征方法和最小二乘意义下以材料色散曲线为基础的反向算法对材料进行了参数估计。文中分析了影响估计准确性的各种因素,研究了低频多模式超声兰姆波定征方法对各材料参数的灵敏度及其在误差传递中的意义。实验结果表明,该方法能够准确估计厚度小到26μm 铝箔的材料参数 It is proposed to estimate the parameters such as longitudinal wave velocity, shear wave velocity, thickness and density in the ultra-thin elastic layer by using low-frequency multi-mode ultrasonic Lamb wave method. Here, “ultra-thin” means that the material thickness h is much smaller than the acoustic wavelength λ in the material, thereby causing the respective echo signals at the front and back interfaces of the material to overlap with each other in the time domain. In this paper, the zero-order symmetry and zero-order symmetry Lambam wave dispersion curves of material are obtained by the water immersion coupling method combined with the design of space wave field and the leakage Lamb wave frequency domain analysis method Wave method, the simplified method, the zero order anti-symmetric Lambam method and the inverse method based on the material dispersion curve in the least square sense, the parameters of the material are estimated. In this paper, various factors that influence the accuracy of the estimation are analyzed, and the sensitivity of the low-frequency multi-mode Lambert acoustic method to each material parameter and its significance in error transmission are studied. The experimental results show that this method can accurately estimate the material parameters of aluminum foil with thickness as small as 26μm