An overview of layerwise theories for composite laminates and structures: Development, numerical implementation and application

This paper investigates the free vibrations of the rotating pretwisted functionally graded (FG) composite cylindrical panels reinforced with the graphene platelets (GPLs) by considering the cantilever boundary conditions. The weight fraction of the graphene platelets in each ply may be different, which leads to the layer-wise functionally graded composite cylindrical panels reinforced with the GPLs. The effective Young's modulus is calculated by the modified Halpin-Tsai model. The effective Poisson's ratio and mass density are derived by the rule of the mixture. The strain-displacement relationship is acquired by the Green strain tensor. Based on the first-order shear deformation theory, Chebyshev-Ritz method is used to obtain the natural frequencies of the rotating pretwisted functionally graded composite cylindrical panel reinforced with the GPLs. The natural frequencies are discussed by considering different material and geometry parameters of the rotating pretwisted functionally graded composite cylindrical panel reinforced with the GPLs, such as the GPL distribution pattern, the GPL weight fraction, the geometries of the GPLs, the pretwisted angle, the presetting angle and the rotating speed. Several validations are carried out, the numerical results are in good agreement with the results of the literature and ANSYS.

Free vibration of rotating pretwisted functionally graded composite cylindrical panel reinforced with graphene platelets

Vibration characteristics of rotating pretwisted composite tapered blade with graphene coating layers

http://www.diva-portal.org/smash/get/diva2:546883/FULLTEXT02.pdf

General shell model for a rotating pretwisted blade

It is very challenging to accurately analyze the displacement and stress fields in the laminated composite structures due to the transverse anisotropy and higher transverse flexibilities. The equivalent single-layer theory (EST) is first developed to simplify this complex 3D problem to a pure 2D problem based on a displacement assumption in the thickness direction. The EST gives good results for the global responses of the very thin laminates with minimum computation cost, but poor results for the local responses at the interfaces and can not presents the zig-zag distribution of in-plane displacements. The elasticity solutions based on the 3D displacement-based finite element method (FEM) can present the accurate displacement and stress fields, but requires huge computational cost. As a quasi 3D method, the layerwise theories (LWT) is more accurate than most of the ESTs, and its computational cost is less than that of the 3D-based displacement FEMs, so it is attracting more and more attention with the rapid development of computer technology. This paper presents an overall review for the LWTs of the laminated composite structures and their applications. In general, there are two basic schemes employed to establish a LWT according to the construction of the displacements fields in the thickness direction. In the first scheme, the laminated composite structures are described as an assembly of individual layers, and these individual layers are combined by the interlaminar relationships to keep the displacement continuity and stress equilibrium. All of the individual layers are simulated by using the EST. In the second scheme, the displacement and/or stress fields along the thickness direction are constructed by a 1D interpolation functions and the in-plane displacement and/or stress fields are discretized by the 2D finite elements. The review in this paper is organized by the this classification.

Layerwise Theories of Laminated Composite Structures and Their Applications: A Review

A rotating turbine blade, as a dynamic system, is modeled to view the insight of its vibration feature at the operating condition. The blade is modeled using the plate structure with the continuum elasticity theory. In order to consider the effect of the rotation, the centrifugal force and Coriolis force are involved in the strain-stress analysis together with the velocity components. Using Hamilton's principle, the equations of motion as well as corresponding boundary conditions are derived for two cases studied in this paper. One case focuses on a straight blade and the other on a blade with a twist angle. A validation for the derivation of the equations of motion is given by some comparisons with results from reference papers.

Jia Sun

Papers

Development of a dynamic rotating turbine blade model