چكيده به لاتين
Shape memory alloy (SMA) in the form of wires or short fibers can be embedded into host materials to form SMA composites. Due to the weak interface in shape memory alloy (SMA) wire-reinforced composites, the influence of interphase on the mechanical properties and stress distribution of composite, is of considerable importance. In this thesis, inhomogeneous interphase is considered, then a three-cylinder axisymmetric model, using a pull out test is developed to predict stress transfer and interfacial behaviour between a SMA wire, an interphase, and a matrix. Matrix phase is considered for two materials including pure resin and composite. For termomechnical behaviuor of the SMA wire, one dimensional Brinson model is used. Based on the stress function method and principle of minimum complementary energy, the stress distribution is derived for three phases. In the SMA wire reinforced composite case by using equal off-axis stiffness matrix, average stress and strain components are derived and then the stress function method is applied. In the SMA wire reinforced resin matrix case, three model including thermal loading model, intact model and partially debonded model are analyzed, but in the SMA wire reinforced composite only intact model is considered. Finite element analysis also performed to simulate stress transfer from the wire to the matrix through the interphase. To evaluate the accuracy of the presented model, the results of the SMA wire reinforced resin matrix case are compared with the results of two-phase composite and finite element results and in the SMA wire reinforced laminated composite case, results of the SMA wire reinforced resin matrix and finite element results are used. By comparing the maximum stress in two models of intact interphase and partially debonded interphase determined that the axial stresses of the middle wire in the intact interphase model at two working temperatures and is approximately 30% and 17% more than from the partially debonded interphase model, respectively. Also, maximum shear stress in the partially debonded interphase model and is approximately 21% and 40% more than from the intact interphase model. In laminated composite, the effect of fiber type, volume fraction of fiber and fiber angle on stress distribution was obtained. The results of carbon / epoxy composite and glass / epoxy composite were compared with pure resin results to investigate the effect of fiber type. The stress distribution results in carbon/ epoxy composites were 7% for maximum shear stress up to 80% for axial stress in the middle of matrix. The volume fraction of the fiber and the fiber angle were selected in the range of 10% to 70% and 10 to 90 degrees. Increasing the volume fraction of the fiber increases the amount of all stress components, but the amount of stress components can decrease or increase with the angle of the fiber.
