Cantrell John H
Nondestructive Evaluation Sciences Branch, NASA Langley Research Center, Hampton, Virginia 23681, USA.
J Nondestr Eval. 2018;37(4). doi: 10.1007/s10921-018-0530-0. Epub 2018 Oct 24.
A model for the amplitude and phase of ultrasonic tone-bursts incident on adherend-adhesive interfaces is developed for both reflected and transmitted waves. The model parameters include the interfacial stiffness constants, which characterize the elastic properties of idealized adherend-adhesive interfaces having a continuum of bonds. The ultrasonic model is linked to the more realistic physico-chemical model of adhesive bonding via a scaling equation that establishes the relationship between the interfacial stiffness constants of the ultrasonic model and the fraction of actual bonds in the physico-chemical model. The link to the physico-chemical model enables a quantitative assessment of the absolute bond strength. The ultrasonic model and scaling equation are applied to the simulation assessment of the absolute bond strength of two aluminum alloy adherends joined by an epoxy adhesive. Model input is obtained from the calculated phase of tone-bursts reflected from the adherend-adhesive interfaces as a function of the interfacial stiffness constants. The simulation shows that the reflected phase is dominated by the first interface encountered by the incident tone-burst with little contribution from the second interface. The simulation also shows that the accuracy in assessing the adhesive bond strength depends on the sensitivity of the reflected phase to variations in the interfacial stiffness constants, reflecting in part the nonlinearity of the scaling relationship.
针对入射到被粘物 - 胶粘剂界面的超声短脉冲串的振幅和相位，开发了一个适用于反射波和透射波的模型。模型参数包括界面刚度常数，这些常数表征了具有连续键合的理想化被粘物 - 胶粘剂界面的弹性特性。通过一个比例方程，将超声模型与更实际的胶粘剂粘结物理化学模型联系起来，该方程建立了超声模型的界面刚度常数与物理化学模型中实际键合分数之间的关系。与物理化学模型的联系使得能够对绝对粘结强度进行定量评估。将超声模型和比例方程应用于对由环氧胶粘剂连接的两种铝合金被粘物的绝对粘结强度的模拟评估。模型输入是根据从被粘物 - 胶粘剂界面反射的短脉冲串的计算相位作为界面刚度常数的函数获得的。模拟表明，反射相位主要由入射短脉冲串遇到的第一个界面决定，第二个界面的贡献很小。模拟还表明，评估胶粘剂粘结强度的准确性取决于反射相位对界面刚度常数变化的敏感性，这部分反映了比例关系的非线性。
