Nonlinear Deforimation?themal Buckling And Vibration Of Shear SMA Fiber Composite Beam

As an important part of the mechanical system,the composite beam is widely used in the fields of aviation, automobile, ship and other mechanical fields because of its high specific strength and specific rigidity,tailorable structural properties. The intelligent material embedded in the composite structure will produce intelligent material structure can improve the static and dynamic properties of the composite structure,which has long been a hot topic of concern. Shape memory alloy (SMA) is a kind of excellent performance of intelligent materials. The SMA is embedded in the composite material in the form of fiber to realize the active control of the mechanical properties of the composite beam. Although much progress has been made, most of the existing studies have been limited to the models of linear composite beams containing SMA fibers, and often do not take into account the effects of shear deformation. In this dissertation, we study the nonlinear static deformation, thermal post-buckling and vibration of SMA fiber composite beam in consideration of shear deformation and geometric nonlinearity. Therefore, the research topic in this dissertation has important theoretical and practical value.In this dissertation, the basic concept and mechanical properties of SMA are briefly introduced, and three typical constitutive relations models are highlighted.The one-dimensional Brinson constitutive relation model is used to study the restrained recovery properties of SMA. The mechanical properties of the composite beams with SMA fibers were calculated by the mixing rate formula. Based on the shear deformation beam theory and Von-Karman nonlinear strain displacement equation and Hamilton principle, the motion equation of SMA fiber composite beam is derived. The Galerkin method and the harmonic balance method are used to solve the nonlinear static deformation, thermal buckling response, free vibration and forced vibration characteristics of SMA fiber composite beams under simply supported conditions. The influence of different parameters including SMA fiber content, initial strain, temperature and aspect ratio on the static characteristics,stability and free and forced vibration characteristics of SMA fiber composite beams were analyzed by numerical calculation. The effect of shear deformation will be studied by using the classical beam theory, the first-order shear deformation beam theory and the higher-order beam theory.The results show that the embedded SMA fiber can effectively improve the nonlinear static deformation, thermal buckling stability and vibration characteristics of the composite beam. The effect of shear deformation is weakened with the increase of the aspect ratio. For the slender SMA fiber composite beam, the influence of the shear deformation on the nonlinear static and dynamic characteristics can be ignored.