Fatigue analysis of adhesive joints with laser treated substrates

Recent literature works focused on the analysis of laser irradiation on the strength of adhesive joints under quasi-static loading conditions. It has been demonstrated that laser surface preparation allows to remove impurity and weak boundary layers from the mating substrates and, depending on the energy density, it is also able to modify surface morphology promoting mechanical interlocking. In previous works, the authors assessed the effect of Yb-fiber laser ablation over the quasi-static strength and toughness, of aluminum and stainless steel adhesively bonded joints. The experimental results demonstrated the ability of laser irradiation to improve the mechanical properties of the joints. The aim of this work is to extend the scope of previous investigations to fatigue loading. Double Cantilever Beam (DCB) samples with laser treated aluminum substrates have been bonded with a two component epoxy adhesive. For comparison standard degreasing and grit blasting have been also deployed for samples preparation. The results have been compared in terms of cycles to failure and the fracture surfaces have been analyzed by means of Scanning Electron Microscopy (SEM) in order to investigate the mechanism of failure.