چكيده به لاتين
In this thesis, the creep behavior of MWCNT and GONP-reinforced adhesive joints was experimentally and analytically investigated. The effects of creep test temperature, load level, weight percentage of nanoparticles and different environmental conditions (including dry, immersion in Persian Gulf sea water and deionized water) on the creep characteristics (including elastic shear strain, creep shear strain and strain-time curve) of adhesive joints was studied. The Burgers rheological model was employed for simulating the creep behaviour of adhesive joints. Semi-empirical models were proposed using response surface methodology which presented the elastic and creep shear strains and the Burgers model parameters as functions of temperature, load level and nano-particle weight percentage. For this purpose, the neat and MWCNT and GONP-reinforced adhesive joints were manufactured with two weight percentages of 0.1 and 0.3. The creep tests were conducted on the specimens exposed to three different environments of dry, immersion in deionized water and immersion in Persian Gulf sea water. The dry creep test results showed that adding 0.1 wt% MWCNTs into the adhesive layer caused the elastic shear strains to decrease by 23%, 45% and 49% and the creep shear strains to decrease by 29%, 33% and 37% compared to the neat adhesive joints for testing temperatures of 30, 40 and 50°C, respectively. The immersion in water results showed that the destructive effect of deionized water on the creep behavior of neat adhesive joints was more significant than that of Persian Gulf sea water. Immersion of the neat adhesive joints in deionized water increased the elastic shear strains by 54%, 47% and 28% and the creep shear strains by 25%, 26% and 8.5% compared to the adhesive joints exposed to dry environment for testing temperatures of 30, 40 and 50°C, respectively. The effects of MWCNTs and GONPs on the creep behavior of adhesive joints immersed in deionized water were also investigated. The results showed that immersion of the adhesive joints containing 0.1 wt% MWCNTs in deionized water lowered the elastic shear strains by 56% and the creep shear strain by 33% compared to the neat adhesive joints immersed in deionized water. The analytical results showed that the Burgers rheological model could successfully simulate the creep behavior of adhesive joints at different stress levels, testing temperatures, MWCNT/GONP weight percentages and dry environmental conditions, immersion in Persian Gulf sea water and immersion in deionized water.
