The effect of torsional vibrations superimposed on a creep loaded adhesive joint on its final tensile properties

Aluminum - epoxy single lap joints were subjected at different temperatures to torsional vibrations at constant amplitude superimposed on a creep load. This combination of dynamic and static stresses was chosen in order to simulate to a certain extent the real service conditions of an ordinary bonded joint. The shear strength of these joints was checked in tension at room temperature after their removal from the special device in which the superimposed stresses were applied. It was found that the shear strength of the joint is very dependent on its thermo-mechanical history. DSC analyses and SEM micrographs of the failure surface were used in an attempt to find some correlation between the mechanical properties and the microstructure of the adhesive.