Nonlinear ultrasonic transmission through thin bonded interface: Theoretical background and numerical simulations

Adhesive bonds in composite structures influence the mechanical behavior of components and limit their load capacity. Consequently, the investigation of the interaction forces in adhesive joints is an important task in nondestructive testing. For this purpose the nonlinear stress-strain relation of adhesive joints for high amplitude excitation resulting in higher and/or sub-harmonics generation can be exploited. This contribution discusses ultrasonic transmission through samples consisting of two plates joined together by a thin adhesive layer. It also describes the calibration procedure of the input and output wave parameters in order to obtain absolute values of the forces acting within the interface. Numerical simulations assist in the interpretation and evaluation of the experimental data.