Discrimination of Epoxy Curing by High Lamb Modes Order

This work is a contribution to the non destructive testing of structural adhesive bonding by ultrasonic methods. The aim of this paper is to link acoustic behaviors of epoxy bulk samples to their level of cure, quantified by a partial or a total epoxy conversion. The bulk longitudinal and shear waves velocities are measured for each sample. They are used to determine the theoretical dispersion curves of Lamb waves. Theoretical results predict a high sensitivity of some high order Lamb modes to the cure level by the variation of their wavenumber, for a given mode and for the same frequency range. In parallel, an experimental study is conducted to determine the experimental dispersion curves. The experimental results and the predicted ones are in a good agreement.