On the influence of the adhesive and the adherend ductility on mode I fracture characterization of thick adhesively-bonded joints

Thicker bondlines along with manufacturing-tolerant and fracture-resistant adhesives are trends visible across different industries, especially maritime. In this work, two contrasting adhesives: an elastic-brittle epoxy-based, a nonlinear-ductile methyl methacrylate (MMA) characterized compared via tensile, compact tension (CT) double cantilever beam (DCB) testing, for steel-to-steel adherends. Significant differences captured between the bonding materials in terms of energy required crack growth: MMA “ductile” adhesive is ∼4 10 times more than epoxy “relatively brittle” CT DCB respectively. While fail due to symmetric in-plane crack, experience multiple cracking originating from high deformations Poisson's effects. Moreover, case adhesive, testing led plastic deformation steel The existing evaluation protocols adopted data reduction effect dissipation theoretically addressed. Despite adherend plasticity, it concluded that growth driven by elastic release, thus, after small correction taking into account initial simple models can still be used. This study highlights potential use ductile instead commonly used brittle ones significantly improve adhesively bonded joints maritime applications which thick bondlines, fracture-resistance characteristics required.