Free-Vibration of Rotating Composite Beams Incorporating Higher-Order Transverse Shear Effects

Author(s):  
N. K. Chandiramani ◽  
L. I. Librescu ◽  
C. D. Shete

Abstract The free vibration behavior of a rotating blade modeled as a laminated composite hollow (single celled) box beam is studied. The geometrically nonlinear structural model developed herein incorporates a number of non-classical effects such as anisotropy, heterogeneity, transverse shear flexibility, and warping inhibition. The centrifugal and Coriolis force field effects are also included. The main focus here being the refinement of the existing model, the traction-free boundary conditions are satisfied here in contrast to the existing model. The resulting linearized equations and numerical results based on them are presented. Results obtained for the present higher-order shearable model are compared with those of the existing first-order shearable and the non-shearable models. Tailoring studies using the present model reveal an enhancement of eigenfrequency characteristics.

Author(s):  
N. G. R. Iyengar ◽  
Arindam Chakraborty

Response of composite laminates under in-plane compressive or shear loadings is of interest to the analyst and designers. Since they are thin, they are prone to instability under in-plane loads. Transverse shear effects are important even for thin laminates since elastic modulus and shear modulus are independent properties. For very thick laminates neglecting transverse shear effects leads to completely erroneous results. A number of different theories have been suggested by different investigators to account for transverse shear effects. In this investigation, an attempt has been made to take into account transverse shear effects for the stability analysis of moderately thick/very thick composite laminates under in-plane compressive and shear loading using a “SIMPLE HIGHER ORDER SHEAR DEFORMATION THEORY” based on four unknown displacements instead of five which is commonly used for most of the other higher order theories. A C1 continuous shear flexible finite element based on the proposed HSDT is developed using the Hermite cubic rectangular element. The analytical results obtained have been compared with the available results in literature. Effect of various parameters like aspect ratio, thickness to side ratio, fiber orientation and material properties have been studied in detail.


Author(s):  
Aniket Chanda ◽  
Utkarsh Chandel ◽  
Rosalin Sahoo ◽  
Neeraj Grover

In the present study, the electro-mechanical responses of smart laminated composite plates with piezoelectric materials are derived using a two-dimensional (2 D) displacement-based non-polynomial higher-order shear deformation theory. The kinematics of the mathematical model incorporates the deformation of laminates which account for the effects of transverse shear deformation and a non-linear variation of the in-plane displacements using inverse sine hyperbolic function of the thickness coordinate. The equilibrium equations are obtained using the minimization of energy principle known as the principle of minimum potential energy (PMPE) which is also based on a variational approach and the solutions are obtained using Navier’s solution technique for diaphragm supported smart laminated composite plates. The responses obtained in the form of deflection and stresses are compared with three dimensional (3 D) solutions and also with different polynomial and non-polynomial based higher-order theories in the literature. The transverse shear stresses are obtained using 3 D equilibrium equations of elasticity to enhance the accuracy of the present results. Various examples are numerically solved to establish the efficiency of the present model.


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