A quantitative imaging of bonding strength at the bonded solid-solid interface obtained by nonlinear test

Abstract

As well known, when a longitudinal wave propagates through an interface with micro-cracks and micro-defects between solids, the contact acoustic nonlinearity (CAN) will be generated dramatically and the nonlinear parameter can be used to contour the bonding state of the interface. However the contour can only show the relative state of bonding strength and can not be used to judge weather the multilayered composite materials in use is safe because the safe judgment is not by the relative state while by the absolute value of the bonding strength. Therefore characterization of quantitative bonding strength at the interface is very important for judging a multilayered material in safe use. In this paper, how to get the quantitative bonding strength from the CAN parameter is studied. After the vibration amplitude of incident focusing wave at the bonded interface was calculated, the standard bonding strength with complete bonding state was established by tension test and CAN parameter is calibrated, the quantitative imaging of the bonding strength is obtained by CAN microscope in experiments. From the imaging, the positions with weak bonding strength could be easily located, which can be used to decide whether the material could be employed continuously.