Fatigue Strength of Al/Epoxy Moulded Joints

Abstract

Fatigue tests of Al/epoxy moulded joints were conducted and the effect of specimen geometry on the fatigue strength was studied. The test specimens used in the experiment were butt-joints, grooved butt-joints and slant butt-joints under bending, and butt-joints under tension.
The stress state for each specimen geometry under fatigue load combined with residual thermal stress was analyzed by elastic FEM, and all the fatigue data were found to be expressed with a single narrow S-N band when they were plotted in terms of the stress component perpendicular to the interface.
The fracture surfaces were also examined and it was shown that the fatigue fracture developed through the four stages starting from stable debond growth along the Al/adhesive interface to the final fracture of epoxy resin.
The mechanism for stepwise transition of the four stages was discussed using fracture mechanics parameters.