Single lap joints bonded with structural adhesives reinforced with a mixture of silica nanoparticles and multi walled carbon nanotubes

The average shear strength and elongation at failure of adhesively bonded single lap joints (SLJs) were studied when different mixtures of two nanoparticles i.e. silica nanoparticles (SNPs) and multi walled carbon nanotubes (MWCNTs) were added to the adhesive. The experimental results showed that adding the mixed nanoparticles had a significant effect on the mechanical behavior of SLJs. The highest improvements in the shear strength and elongation at failure among different weight percentages of the investigated mixed nanoparticles were 28% and 36%, respectively, which were related to 0.8 wt% of the mixed nanoparticles. Moreover, the improvement of mechanical properties due to addition of the mixed MWCNTs and SNPs was higher than the improvements obtained for corresponding single-type nanoparticles with the same weight percentages. The fracture surfaces and damage mechanisms of single lap adhesive joints were also investigated and a correlation between the joint strengths and the fracture surfaces was found.