چكيده به لاتين
In this research, the fracture characterization of adhesively bonded joints made with glass/epoxy composite substrates was investigated. The substrates were bonded with an epoxy resin and reinforced with aligned carbon nanotubes and subjected to mode I, mode II, and mixed-mode (I/II) loading conditions using double cantilever beam (DCB), end-notch flexure (ENF), and mixed-mode bending (MMB) tests, respectively. First, the compliance-based beam method equations were obtained for an unreinforced MMB specimen, and then the resistance curves obtained using this method were compared with the classical methods. To align carbon nanotubes in the adhesive layer, electric and magnetic fields were employed. However, due to the insufficient magnetic properties of carbon nanotubes, iron oxide (Fe3O4) nanoparticles were coated on multi-walled carbon nanotubes (MWCNT) using the chemical coating process. It was found that this method was successful for particle hybridization. To improve the dispersion quality of particles in the epoxy resin, which is a critical factor in enhancing the properties of nanocomposites and reinforced adhesives, the effects of sonication parameters (including five output powers and three times) and the use of solvents (including five different solvents) on the thermal stability, tensile modulus, and strength of MWCNT-Fe3O4/epoxy nanocomposites were investigated. This resulted in a 47% improvement in tensile strength compared to the neat epoxy. The fracture characterization of adhesive joints reinforced with randomly dispersed and aligned particles along the thickness of the adhesive with electric and magnetic fields under mode I, mode II, and mixed-mode loadings was carried out using the compliance-based beam method. Adhesive joints reinforced with aligned particles under an AC electric field showed a significant improvement in fracture energy of mode I, mode II, and mixed mode with mixed-mode ratios of 0.33 and 0.66, respectively, compared to unreinforced joints. The load-displacement data from the numerical solution were determined by the bilinear traction-separation laws obtained from the direct method and compared with the experimental data.
