چكيده به لاتين
In recent years adhesively bonded joints has been used in various industries due to their uniqe features in comparison with other conventional fastening joints. Therefore, stress distribution, strength and fracture toughness of the adhesive layer are of the utmost importance in adhesively bonded joints. Using metallic fibers and nano particles are some proposed methods to achive this goal. Shape memory alloys are group of smart materials that attracted the attention of different industries because of their significant features due to the short time of their discovery. Strain recovery resulted from mechanical force by applying heat is one of the most important properties of this alloys. In the first part of the present research, aluminum wires with different geometric shapes such as straight wires, twisted wires, spring-shaped wires and a combination of MWCNTs and aluminum straight wires were used as reinforcement in the adhesive layer and the improvement about %118, %48, %78, %165 and % 171 was observed in the shear strength of SLJs respectively. Experimental results also indicated that the maximum improvement of elongation at failure obtained approximately %371 while a combination of MWCNTs and aluminum wires were used in the adhesive layer. Additionally, in the second part of this study, the effect of incorporating the adhesive layer with shape memoey wires with various pre-strain rate and the shape memory effect of these alloys on improving the mechanical properties of SLJs was studied experimentally. According to the experimental results, maximum shear strength and elongation at failure occurred when a combination of 0.3 wt% of MWCNTs and sma wires with %6 pre-strain rate were used as reinforcement in the adhesive layer and the improved values reaches to %44 and %492 respectively. Moreover, results indicated that by increasing the pre-strain rate of shape memory wires, mechanical properties of SLJs improved marginally but when a combination of SMA wires with various pre-strain rate and 0.3 wt% of MWCNTs were used as reinforcement in the adhesive layer, average shear stress and elongation at failure went up considerably compared to unreinforced adhesive. Moreover, the fracture surfaces and damage mechanisms of SLJs were investigated by using SEM analysis and it was revealed that by incorporating the adhesive layer with nanoparticles and wires, the fracture roughness increased and wrinkles was observed on the samples fracture surfaces and this was in direct correlation with the joints strength values and fracture surfaces.
