Toughening effect in adhesive joints comprising a CFRP laminate and a corrugated lightweight aluminum alloy

As the demand for structural light-weighting continues to rise, so does the interest in bonding with structural adhesives. However, adhesive joints are subjected to the nucleation and growth of cracks, and there is a growing need for toughening strategies that can prevent catastrophic failures. This work focuses on secondary bonded composite/metal joints and explores a toughening approach enabled by a snap-through cracking process. A composite flat panel is bonded with a corrugated aluminum substrate with a square-wave profile, whose geometry is defined by grooves’ spacing, depth, and width. These key geometrical parameters provide opportunities to tailor the mechanics of crack growth and were chosen by resorting to finite element simulations with cohesive elements. The computational results are validated by experiments that systematically show the occurrence of snap-through cracking and a significant enhancement of load bearing capacity and dissipated energy (up to 260%) compared to adhesive joints without corrugation.