3. Adhesives and Composites
My part of this program was to investigate a nondestructive method for measuring the cohesive strength properties of adhesively bonded joints.
I started this problem by viewing a reasonably fundamental study in modeling the adhesive as a layer between two infinite aluminum adherends. You can set up wave potentials in these different regions in terms of reflected and transmitted waves, as is seen in Fig. 1. If you set up your wave number in a very classical manner, where everything is elastic and there is no damping, you just get a regular Rayleigh-type solution. If you desire to include the damping of the adhesive layer, then you must have a complex wave number. The appropriate relationship was derived by Brekhovshikh. We took his relationships and did parametric studies on the bond line in terms of the acoustic properties of the adhesive.
Flynn, P. L., "Cohesive Strength Prediction of Adhesive Joints" (1977). Proceedings of the ARPA/AFML Review of Progress in Quantitative NDE, July 1975–September 1976. 6.