A nanomodified-ultrasonic method to improve the shear strength of adhesively bonded composite joints

Adhesive bonding method has become prevalent in joining composite structures in the aerospace and automotive industries. The bonding quality is critical in terms of service safety. This research proposed a nanomodified-ultrasonic method to enhance the shear strength of adhesively composite joints. Functional multi-walled carbon nanotubes (MWCNTs) were dispersed into the adhesive, followed by the ultrasonic vibration during the bonding process. Orthogonal experiments considering different combinations of the NWCNT concentrations, ultrasonic power, and ultrasonic time were conducted to investigate the effect of different factors and to obtain the optimal processing parameters. Results indicate that the nanomodified-ultrasonic method is beneficial to the composite bonded joint and a maximum increase of 75.1% in shear strength was achieved. Furthermore, the bondline before testing and fracture surface were critically analyzed to illustrate the enhancement mechanisms.