摘要
多层薄膜-基底结构在工业领域有广泛应用,其中薄膜的厚度与弹性参数等特性对结构与器件性能有显著影响。但对多层薄膜材料参数进行无损定征较为困难。考虑界面波对界面附近材料特性敏感的特点,以及分层薄膜导致液固界面Scholte波频散与分层材料速度分布密切相关等因素,文章首先利用全局矩阵理论分析了分层结构中的声传播,并给出界面上脉冲激励的声压表达式,据此对水浸双层薄膜-基底三层结构材料声速呈正梯度、负梯度、随机分布三种结构中液固界面Scholte波的频散曲线进行数值计算。进一步详细计算了法向脉冲线源激发的界面波瞬态信号随薄膜厚度的变化。结果显示,三种结构中两层薄膜厚度均对液-固界面波频散特性有显著影响,同时不同膜厚对不同频段的Scholte波的“捕获”作用(频率选择性)十分明显。该结果为进一步利用Scholte波频散特性进行多层薄膜厚度定征提供了理论依据。
Multilayer film-substrate structures have been widely used in the industrial field,in which the thickness and elastic parameters of thin films have significant effects on the structure and device performance.However,it is difficult to determine the material parameters of multilayer films in nondestructive testing.Considering that the interface wave is sensitive to the materials near the interface and that the Scholte wave dispersion caused by layered films is closely related to the velocity distribution of layered materials,in this paper,the sound propagation in the layered structure is analyzed by using the global matrix theory and the expression of the sound pressure with impulse excitation on the interface is given.On this basis,the Scholte wave dispersion curves at the liquid-solid interfaces in the water-immersed bilayer film-substrate structures with the sound speeds showing positive gradient,negative gradient and random distributions are numerically calculated.Furthermore,the variation of the transient interface wave signal excited by the normal pulse line source with the thickness of the film is calculated in detail.The results show that the thickness of two films has a significant effect on the dispersion characteristics of liquid-solid interface,and the"trapping"effects(frequency selectivity)of Scholte waves in different frequency bands are obvious for different film thicknesses.The results provide a theoretical basis for further thickness determination of multilayer films based on Scholte wave dispersion characteristics.
作者
宋博文
马琦
胡文祥
SONG Bowen;MA Qi;HU Wenxiang(Institute of Acoustics,Tongji University,Shanghai 200092,China;Edan instrument,Shenzhen 518122,Guangdong,China)
出处
《声学技术》
CSCD
北大核心
2023年第4期426-430,共5页
Technical Acoustics
基金
国家自然科学基金(11774264)。
