低频超声类兰姆波超薄黏结复合结构定征方法

提出用低频超声类兰姆波定征方法来估计超薄黏结复合结构各层与黏结层的厚度、密度、纵波声速和横波声速等参数.采用超声耦合剂耦合方式,结合超声泄漏类兰姆波频域分析方法获取黏结复合结构类兰姆波频散曲线,提出以频散特性为基础的低频超声类兰姆波定征方法和在最小二乘意义下以频散曲线为基础的反向算法对超薄黏结复合结构各层与黏结层进行了参数估计.还分析了影响估计准确性的各种因素,研究了低频超声类兰姆波定征方法对超薄黏结复合结构中各层参数的灵敏度及其在误差传递中的意义.实验结果证实,对于超薄不锈钢/黄铜黏结复合结构,该方法能够准确估计各层h<0.05λ复合结构的声学参数.

Low Frequency UltrasonicMulti-mode Lamb-like Wave Method for Characterizing the Ultra-thin Bonding Composite

A low-frequency ultrasonic Lamb-like wave method suitable for characterizing the thickness, density, shear and longitudinal wave velocities of the ultra-thin bonding composite is presented. The dispersion property of the low frequency Lamb-like wave propagating along the ultra-thin bonding composite is derived, which is the basis of the characterization method. In conjunction with the method of the least square, the secant algorithm is used to estimate each layer's parameters of the ultra-thin bonding composite. The reasons for evaluation error of the parameters and the sensitivity of the method for different parameters are analyzed. Using the ultrasound coupler and a pair of broadband longitudinal wave transducers with 1MHz center frequency, we can successfully estimate the parameters of the ultra-thin bonding layer (with h of each layer smaller than 0.05λ) of the steel/brass composite by employing the leaky guided wave frequency-domain analysis method.