مهندسی مکانیک شریف (Nov 2018)
BOUNDARY LAYER ANALYSIS IN ROTATING CROSS-PLY HYBRID COMPOSITE CYLINDER WITH DIFFERENT EDGE CONDITIONS
Abstract
Due to important rule of edge stresses in the delamination and local failure of laminated structures, the objective of this work is to analyze the interlaminar stresses in laminated hybrid composite cylindrical shell which is subjected to centrifugal body force using layerwise theory of Reddy (LWT). The model is under centrifugal forces caused by rotation of the cylinder about its axis. The principle of minimum total potential energy is used to obtain the governing equations of the rotating cylinder. The layerwise theory (LWT) of Reddy is employed for discretization of the governing equations to a system of ordinary differential equations in terms of the displacement of numerical surfaces. To solve the equations of motion of the cylinder in the LWT, the equation is written in the decoupled form by definition of modal space variables. An analytical solution is presented for governing equation. The solution is completed by imposing the boundary conditions in the edges of the cylinder. The interlaminar and in-plane stresses are obtained using the displacement field of layerwise theory for the free and clamped boundary conditions. The interlaminar stresses in the Hybrid cylindrical shell are obtained using two different methods, the constitutive law of the numerical layers, and integrating the equilibrium equations of motion. To validate the results, the results of LWT for cross-ply cylindrical shell are compared to those of Finite element solution in the commercial finite element code Ansys. The results showed an excellent accuracy of the layerwise theory in calculating the interlaminar and in-plane stresses in hybrid cylinder. Various figures from the distribution of the stresses along the interfaces of layers and through the thickness of rotating cylinder are presented in the numerical results. The effects of the geometry, the types of layering, the speed of rotation and hybridation of laminated cylindrical shell on the interlaminar stresses are analyzed. Consequently, the delamination of the layered can be predicted and prevented.
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