The main target of this article is to evaluate the free-vibrational attributes of the thin-walled layered composite panels with constant and variable thickness. It is evident that the performances of thin-walled structures are significantly depend on the mechanical properties. In order to reach to high performance, a type of laminated composites is employed in which the resin is reinforced by the carbon nanotubes (CNTs) in form of the randomly oriented or aligned. Consequently, the mechanical characteristics of the introduced composites are characterized in 3-phase of CNTs, polymer and fibers. The pertaining formulation of the free vibration analysis is extended according to the degenerated-shell assumptions. The extended equations are numerically solved using a novel combined formulation integrated of finite element and isogeometric analyses (FEM, IGA), which is entitled isogeometric finite strip method (IG-SFSM). The results of proposed formulation is approved by comparing with the existent ones in the present references. The sufficiency of the present method and the proposed novel formulation, some instances are bring up incorporating various lamination-schemes, CNTs and fibers volume fractions, CNTs distributing, geometries and constrains. The achieved results exhibited that the employed three phase composite leads to improve the dynamic characteristics of the composite shells, significantly.
