چكيده به لاتين
In recent years, the use of adhesively bonded joints has been increased due to their advantages over other bonding methods. A uniform stress distribution and low-cost process of adhesive joints can be mentioned as examples of the advantages. Despite all the advantages, adhesive joints also have weaknesses; one of these weaknesses is their low fracture toughness, which has a low resistance to crack growth. One of the ways to overcome this problem is to use nanoparticles in the adhesive.
In this study, two types of nanoparticles, carbon nanotubes and graphene oxide nanoplatelets were used to reinforce an epoxy adhesive. These nanoparticles have used in two random and aligned distribution in three different weight percentages (0.1, 0.3 and 0.5), and their effect on the fracture behavior of composite bonding joints have been investigated. The substrates are made of glass-carbon-epoxy composites; a unidirectional carbon fabric is used as an electrode for creating alternating electric field (AC) and the particles are aligned along the adhesive thickness. The fracture energy measurement is done by a double cantilever beam standard test. The highest improvement in the initial fracture energy of the joints happened in 0.3 wt% of aligned nanoparticles, which was 179% for carbon nanotubes and 349% for graphene nanoplatelets. The observed results indicated that the graphene oxide nanoplatelets are completely superior to carbon nanotubes in improving the fracture behavior of adhesively bonded joints.
The scanning electron microscopic images of the fracture surfaces were used to study the toughening mechanisms of nanoparticles. Crack deviation, bridging, and pull-out mechanisms were observed for carbon nanotubes. For graphene nanoplatelets, in addition to these three mechanisms, crack tip pinning, the debonding and plastic void growth were also observed.
