The use of power ultrasound energy to support interface formation for structural adhesive bonding

A reliable performance is what the engineers need to take advantage of for the weight-saving potential of adhesive bonded structures. The present paper presents a new approach to ensure improved and quality assured adhesive bonds by using power ultrasound in combination with the adhesive application to support interface formation. In contrast to various known publications in this paper ultrasound is not used at low power-level as for inspection by nondestructive testing (NDT) but to influence interface cleaning and to improve contamination tolerance of the adhesive bonding process.Power ultrasound with an intensity of 10–100 W/cm2 is used to transfer energy for a short time into the liquid adhesive. The general idea and various advantages for adhesive bonding by supplying energy for the developing adhesive/substrate interface are presented and discussed. Power ultrasound can be used: to remove surface contaminations, to obtain contamination tolerance for the bonding process, to improve substrate wetting, to mix adhesives, to outgas adhesives and the substrate surface or to establish chemical reactions at the interface.Results from adhesive bonded lap shear and roller peel tests with contaminated samples, rheological measurements and pictures from high speed videos demonstrate the effectiveness of the approach.