A third-order polynomial for the free vibration response of 3D braided curved panels using various boundary conditions

Abstract

3D braided composite is gaining popularity over the traditional composite because it has a higher impact resistance, fatigue strength, stiffness in the thickness direction, anti-delamination capability, etc. Based on bridging models, the fibers are considered as transversely isotropic and matrix isotropic. The equivalent material properties of the composites are computed using a volume averaging method (VAM). The four steps 1 × 1 braided technique are introduced to manufacture the 3D braided singly and doubly curved shell panels. The bridging model claimed to be more accurate in predicting mechanical properties and shear modulus in comparison with the other method. In the present study, the free vibration response of 3D braided curved panels is obtained using finite element methods (FEM). A third-order shear deformation (TSDT) with twelve degrees of freedom per node is for the first time employed in 3D braided panels using eight nodded isoparametric formulation. In this theory, the transverse displacement is the function of the thickness coordinate. In reality, the normal stress of the thick shells in the thickness direction can't be neglected. This theory having the capability of predicts the normal stress in the thickness direction. Hence, to predict the accurate results of the 3D braided shell, it has more capability compared to the other shell theory. The free vibration results of the shell panels' viz. cylindrical shells (CYS), elliptical paraboloid shells (EPS), and hyperbolic paraboloid shells (HPS) are computed at a different braided angle, braided volume fraction, aspect ratio, thickness ratio, curvature ratio, and boundary conditions, etc.

HIGHLIGHTS

• The equivalent material properties of the 3D braided composites are calculated using bridging models based on a volume averaging method (VAM).

• The bridging model claimed to be more accurate in predicting mechanical properties and shear modulus in comparison with the other method.

• A third-order shear deformation (TSDT) with twelve degrees of freedom per node is for the first time employed in 3D braided panels using eight nodded isoparametric formulation.

• In this theory, the transverse displacement is the function of the thickness coordinate. To predict the 3D braided shell's accurate results, it has more capability than the other shell theory.

• The free vibration results of the shell panels' viz. cylindrical shells (CYS), elliptical paraboloid shells (EPS), and hyperbolic paraboloid shells (HPS) are computed at a different braided angle, braided volume fraction, aspect ratio, thickness ratio, curvature ratio, and boundary conditions, etc.

Keywords:

• Doubly curved shells
• vibration
• braided composite
• 3D finite element
• TSDT

Acknowledgment

The authors are thankful to the Indian Space Research Organization (ISRO) for financial supports. The authors are also grateful to the Department of Aerospace Engineering, IIT-Kharagpur, for providing an excellent research environment.