چكيده به لاتين
Abstract:
Adhesively bonded joints are extensively used in sensitive industries due to their exclusive charactristics in comparison with other conventional joints. Adding particles and fibers to the adhesive layer is a method suggested to increase the strength of the adhesive joints. In the first stage of this research, the effect of adding silica nanoparticles (SNPs) and multi-walled carbon nanotubes (MWCNTs) as single-type nanoparticles and hybrid nanoparticles with equal weight ratio (1:1) at three weight percentages of 0.2%, 0.5% and 0.8% on the mechanical properties of single lap joints (SLJs) including average shear strength and elongation at failure point was investigated. The trend of improving the average shear strength and elongation at failure point of SLJs reinforced by adding SNPs into the adhesive layer increased, such that the average shear strength and elongation at failure values of SLJs reinforced by 0.8 wt% SNPs (maximum improvement) increased by 26.87% and 19.54% comparing unreinforced adhesive joint, respectively. In SLJs reinforced by single-type MWCNTs, the average shear strength and elongation at failure values increased up to 0.5 wt% and then decreased, such that at 0.5 wt% MWCNTs, the values of average shear strength and elongation at failure increased by 15.43% and 20.1% comparing with unreinforced adhesive joints, respectively. The effect of adding hybrid nanoparticles including MWCNTs and SNPs with equal weight ratio improved the average shear strength and elongation at failure values by increasing the weight percentages of hybrid nanoparticles, such that at 0.8 wt% of hybrid nanoparticles (maximum improvement), the average shear strength and elongation at failure values increased by 28.27% and 36% comparing with unreinforced adhesive joint, respectively. Finally, the effective mechanisms on increasing or decreasing the mechanical properties of reinforced SLJs by a scanning electron microscope images (SEM) were identified.
In the second stage of this research, the effect of metal macrofibers in longitudinal and lateral directions on mentioned mechanical properties and peel and shear stresses distribution at horizontal distances of 0.5, 1 and 1.5 mm was investigated using experimental study and finite element modeling. The obtained results showed that the longitudinal direction of metal macrofibers due to high load bearing in the adhesive layer had a significant role in improving peel and shear stresses distribution, such that at 1 mm horizontal distance (maximum improvement), the average shear strength and elongation at failure values increased by 50% and 36%, respectively. However, the mentioned mechanical properties decreased regularly by the reduction of the horizontal distances between the metal fibers in the lateral direction in the adhesive joint.
Keywords: Single lap joints; nanoparticles reinforcement; metal macrofibers; mechanical properties
