A method to quantify the interface shear stiffness, adhesive shear modulus and adhesive thickness in an aluminium-epoxy-aluminium joint is presented. Shear horizontal guided waves are considered to infer the properties. A numerical model that employs spring stiffness boundary conditions at the aluminium-epoxy interface was developed to generate dispersion curves. The sensitivity of the first four SH-like modes to epoxy thickness, interface shear stiffness, and adhesive shear modulus are analyzed. The dispersion analysis reveals that higher-order anti-symmetric modes are sensitive to all three parameters, whereas the symmetric modes are sensitive only to adhesive thickness. Hence to prevent false alarms that might arise while assessing the bond conditions, symmetric and anti-symmetric modes should be simultaneously generated. Periodic permanent magnet (PPM) electromagnetic acoustic transducers (EMATs) are used to generate and detect SH-like modes. Utilizing the constant wavelength property of PPM-EMATs, SH₂-like and SH₃-like modes are generated. Short-time Fourier transform (STFT) is used to separate the modes merged in the received time response. By overlaying the dispersion curves of SH₂-like mode on STFT, the thickness of epoxy is quantified. The dispersion curves of SH₃-like mode are generated using the measured thickness and overlaid on STFT to measure the interface shear stiffness and epoxy shear modulus. The proposed method is experimentally demonstrated on aluminium-epoxy-aluminium samples of different surface treatments. The study demonstrates a reliable nondestructive evaluation of adhesive bonds that reduces possible false alarms.

提出了一种量化铝-环氧-铝接头中界面剪切刚度，胶粘剂剪切模量和胶粘剂厚度的方法。剪切水平导波被认为可以推断出这些特性。建立了在铝-环氧树脂界面采用弹簧刚度边界条件的数值模型，以生成色散曲线。分析了前四个SH样模式对环氧树脂厚度，界面剪切刚度和粘合剪切模量的敏感性。色散分析表明，高阶反对称模式对所有三个参数均敏感，而对称模式仅对胶粘剂厚度敏感。因此，为防止在评估键合条件时可能出现错误警报，应同时生成对称模式和反对称模式。周期性永磁体（PPM）电磁声换能器（EMAT）用于生成和检测类似SH的模式。利用PPM-EMATs，SH的恒定波长特性产生类似于₂和类似于SH ₃的模式。短时傅立叶变换（STFT）用于分离在接收到的时间响应中合并的模式。通过在STFT上叠加类似SH ₂的模式的色散曲线，可以定量环氧树脂的厚度。使用测得的厚度生成类SH ₃模式的色散曲线，并覆盖在STFT上以测量界面剪切刚度和环氧剪切模量。在不同表面处理的铝-环氧-铝样品上通过实验证明了该方法的有效性。这项研究表明，对胶粘剂进行了可靠的非破坏性评估，可以减少可能的误报。