Sharif Digital Repository

Special superelements are often used to improve the computational efficiency and improve accuracy of finite element modeling. Structures with tapered and spherical geometry exist in many engineering problems. In this work, special tapered and spherical superelements are presented that can be used for modeling of tapered and spherical bodies in thermo mechanical analyses with computational efficiency. The performance of these superelements under thermal and structural loads is demonstrated by presenting several examples and comparing the results with those from conventional 3D brick elements, which shows high accuracy at reduced computational cost  

The aero-thermo-elastic stability of layered cylindrical shells with viscoelstic cores is investigated. The Donnell's shell theory for the outer layers and the first order shear deformation theory for the viscoelastic layer are employed in conjunction with the von Karman-Donnell kinematic nonlinearity to construct the model. The pre-stresses and pre-deformations arisen from the temperature rise and static aerodynamic pressure are first determined by solving the nonlinear thermo-elastic equilibrium equations using by an exact analytical method. The results are then used in the linear aeroelastic stability equations and analyzed with the Galerkin's procedure to determine the supersonic flutter...