effect of viscoelastic interfaces on thermomechanical behavior of a layered functionally graded spherical vessel

In layered structures, the interface of layers is not always perfect and the analysis of problems which have imperfect interfaces is of the high level of importance. in this paper, an analytical approach is used to study the behavior of a layered functionally graded spherical vessel under thermal and mechanical loadings at the inner and outer surfaces. the interfaces of the layers in the vessel are considered to be imperfect and a viscoelastic layer of negligible thickness is assumed between any two layers. the behavior of these viscoelastic layers is modeled by means of kelvin-voigt model. in order to solve the problem, the governing equations of each layer are extracted via the thermoelasticity theory and by applying the appropriate boundary conditions at the interface of the layers, the overall displacement and stress fields are found in the vessel and numerical results are presented for different parameters. the obtained results show that the stiffness of the viscoelastic layer affects the value of the displacements and the stresses as well as the stabilization time of the system. however, changing the damping parameter of the kelvin-voigt model only changes the stabilization time and not the values of the displacements and stresses.