Quantitative Bestimmung der Haftfestigkeit mittels nichtlinearer Akustik gezeigt am Beispiel von PVB-geklebtem Verbundglas.
Quantitative determination of adhesion by nonlinear acoustic technique shown at the example of PVB-bonded glass
A quantitative determination of adhesion strength is very difficult. There exist several models based on a macroscopic description of the adhesion strength using for example the extended Hooke's law or nonlinear spring relations. The approach we use is the microscopic description of the adhesion strength by the interface restoring forces. Using nonlinear expressions for the restoring forces we can show that a narrowband ultrasonic wave transmitting the interface is modulated by the characteristic restoring force versus distance relation of the interface. In particular higher harmonics of the base frequency are generated. By evaluation of the amplitude of the higher harmonics as a function of the interface displacement, the adhesion strength can be determined quantitatively. An application of this new technique is demonstrated by glass-polymer-composites with different humidity content. A good agreement between the adhesion strength measured by mechanical testing and our nondestructive testing results is found.