Image method for measuring normal interfacial stiffness

This paper proposes a new method for measuring normal interfacial stiffness. The contact interface is traditionally equivalent to some springs, but this general equivalent method is proved not sufficiently accurate in processing the elastic-plastic rough contact. The improved interfacial equivalent method is presented to remove the inaccuracy by introducing a contact layer, which considers the plastic zone beneath the rough surface. On the basis of the new method, the image method is proposed for measuring the improved interfacial stiffness. This method is fulfilled by using an image registration method and a sub-pixel algorithm to obtain the deformation of the contact layer and the smooth layer. Simultaneously, the ultrasonic measurement is carried out to measure the ultrasonic interfacial stiffness. The comparative results reveal that the measurement data of the improved interfacial stiffness show better agreement with the numerical results.