Effect of Longitudinal Interfacial Defects on fracture Energy variation in DCB Bonded Specimens

Abstract The primary aim of this investigation is to develop an analytical technique that can accurately estimate the fracture energy at the crack front while accounting for the localized interface properties. To achieve this goal, the study employs Double Cantilever Beam (DCB) specimens made of Aluminium alloys that have been chemically treated, as well as Titanium alloys that have been Laser texturized. Additionally, longitudinal defects are introduced within the bond line, specifically at the interface between the adhesive and adherents, with a parallel orientation to the crack direction. Initially, the investigation involved the characterization of bare surfaces, independent of their adhesive strength. Subsequently, Double Cantilever Beam (DCB) tests were conducted on specimens that had defects of various widths in the bonded region. The results obtained from these experiments confirmed the accuracy of the analytical estimations. It has been explained too that adhesive stiffness has a major role while mixing local fracture energies at crack front. Additionally, using a damage model, the deformation of the crack front was numerically observed and verified by capturing crack front shape while DCB testing. An interpretation was provided to explain the findings.