Measuring adhesion strength of epoxy-based adhesives under quasi-static and dynamic loading conditions

Abstract

Adhesively bonded joints are very common in aerospace applications. They are used in the fabrication of metal and composite components as well as in their repair work. Besides subjecting the interface to more uniform stress distribution, the bonded joints are simple and more efficient when compared to mechanical fastening. Since the reliability of components and structures depends upon the strength of bonded joints, adhesion strength has become an essential design and fabrication parameter. In this investigation, the interface strength between the metallic base and epoxy-based adhesive is assessed by performing quasi-static and extreme dynamic experiments. New test methods are developed by performing computational analysis with the objective of nullifying the stress concentration effect near the interface edge. Quasi-static adhesion tests performed using modified butt-joint specimens exhibit the interface strength between the aluminum and adhesive as 3.07 MPa. Upon subjecting the interface to a strain rate of ∼107/s by employing laser-induced stress waves, the interface strength is evaluated to be 213 MPa. The laser spallation technique, combined with the Michelson interferometer, was used to perform the optical measurements.