چكيده به لاتين
Considering the widespread use of adhesive joints, the researchers worked on strengthening this type of joint using methods such as the addition of nanoparticles to adhesive. By adding nanoparticles, the adhesive layer becomes a kind of nanocomposite. In this study, the effect of reinforcing nanocomposites with MWCNT-Fe3O4 hybrid nanofillers and the role of the dispersion quality of these nanofillers were investigated. The properties of nanocomposites can be improved by aligning nanofillers. Thus, the effect of the alignment of the MWCNT-FE3O4 hybrid particles in the 0°, 45° and 90° directions was investigated to find the best orientation in adhesive joints. The nanofillers dispersion quality in epoxy resin has a great influence on improving the properties of nanocomposites. To achieve the best dispersion of nanofillers, various sonication powers and times were studied, and 240 W and 15 min power and time were selected as optimal values. Also, five different solvents were used and chloroform was selected as the most suitable solvent. To investigate the effect of the alignment of the MWCNT-Fe3O4 hybrid nanofillers on improvement of the mechanical properties of the adhesive joint, three types of tests including double cantilever beam (DCB), end-notched flexure (ENF) and mixed mode bending (MMB) were used. The highest increase in the maximum load in all loading modes was obtained when the nanofillers were aligned in the 90° direction. The most improvement in the maximum load compared to the non-reinforced sample under modes I, II, and I+II loading, was 60%, 45%, and 31%, respectively. Also, the highest increase in fracture energy compared to the non-reinforced samples in modes I, II, and I+II were obtained, as 135.5%, 221.4%, and 36.93%, respectively. The fracture surfaces were studied using FESEM micrographs and the fracture micro-mechanisms were determined. To validate the experimental results, the cohesive zone model method was used for the numerical simulation of all the adhesive joint samples. The load-displacement diagrams determined from the numerical solution were obtained with appropriate accuracy on the diagrams extracted from the experimental results.
