چكيده به لاتين
Nowadays due to the special properties of shape memory alloys, the use of these materials as mechanical properties enhancers in various industries such as aerospace and medical sciences is increasing every day. Also with the increasing applications of adhesive joints, the discussion of increasing strength and improving the mechanical properties of these joints is great importance.
In this study, we have tried to strengthen the adhesive layer of single lap joints by aluminum and nitinol superlasticity wires to increase the mechanical properties of these joints especially their shear strength. To achieve this goal, two types of fiberglass composite and aluminum substrate were used. In the first state, the tests were performed with composite substrate. Tensile tests were performed to determine the effect of insertion of the wires, Then three types of samples were tested with 3, 6 and 9 number of aluminum and nitinol wires. In the second step, the same procedure was followed for aluminum substrate.
By analyzing the results of the tensile tests of the composite joints, it was found that the insertion of the wires did not significantly affect on the shear strength of these joints, regardless of their type. The highest increase in properties is happened when there were 9 wires in the adhesive layer was only 11%. The reason for this ineffectiveness was the type of failure mechanism in these joints. Because the crack would not pass through the adhesive layer and it was growing on composite substrate layers, Such that the top layers were separated from the substrate.
The results obtained from aluminum bonding fittings were remarkable. The shear strength of samples with 3, 6, and 9 number of aluminum wires increased by approximately 10, 24 and 39%, respectively, And reinforced joints with 3, 6 and 9 nitinol wires increased by approximately 17, 42 and 66%, respectively. The main reason for this increase in strength is the increase in adhesion layer toughness, the prevention of crack growth in the adhesive layer and the energy absorption and loadability of the wires in the loading process.
