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Department of Mechanical and Industrial Engineering >
Master of Engineering (M.Eng.) project reports >

Please use this identifier to cite or link to this item: http://hdl.handle.net/1807/25216

Title: Effect of Perfectly Aligned CNTS Under Cohesive Crack Bridging in Adhesive Joint
Authors: Cornwell-Mott, Benjamin
Advisor: Meguid, Shaker A.
Keywords: CNTS
adhesive joint
Issue Date: 23-Nov-2010
Abstract: Recent advances in nano-engineering have prompted the use of nanofillers to strengthen composites and adhesive joints. This is because of the phenomenal mechanical properties that these nanotubes possess. For example, carbon nanotubes have elastic modulus ~1 TPa, and tensile strengths of ~100 GPa, which are more than 300 times those of a polymeric material. It is the purpose of this project to quantify the exceptional effect of nanofillers in cohesive crack bridging in structural adhesive bonds (SABs) for the aircraft industry. In this study, we assume that the high aspect ratio nanotubes are perfectly aligned in a thermoset epoxy adhesive. We carried out finite element modeling of the nano-reinforced SABs taking into account the constitutive law of the nanofillers by using the atomistic-based continuum finite element model. A crack in the nanocomposite is propagated using the virtual crack closure technique and the resulting fracture toughness is calculated. The analysis was conducted using atomic-based continuum finite element in which the constitutive laws for the different phases were carefully selected. Specifically, the Lennard-Jones inter-atomic potentials were used to treat the nanotubes and continuum constitutive laws were used for the SABs. The model represents nanofillers pullout with nonlinear springs and the epoxy is modeled with 2D plane stress elements. Our work reveals that the introduction of perfectly aligned CNTs results in improvements in fracture toughness of the composite of up to 195% at 0.5 wt%. Increasing the weight percentage of carbon nanotube fillers was found to increase the fracture toughness almost linearly. The effect of alignment on the bridging phenomena yields significantly higher toughness values than those typically found experimentally, but this correlates well with studies regarding the effect of nanotube alignment.
URI: http://hdl.handle.net/1807/25216
Appears in Collections:Master of Engineering (M.Eng.) project reports

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