Mehdi Hashemi - Mechanical Rotary Equipment Research Department, Niroo Research Institute (NRI), Tehran;

In this paper, buckling analysis of a laminated fiber reinforced composite cylindrical shell in which volume fractions of its fibers vary longitudinally, is studied under axial compressive load by using a semi-analytical method. The distribution of volume fraction of fiber in base matrix is based on power law model. In addition, the first order shear deformation shell theory is employed for strain field in kinematic relations. Then, weak form formulation and spatial approximations of variables are utilized to discretize equations of equilibrium of this cylindrical shell under axial load. Primarily, the validity of the results obtained for minimum axial buckling load are evaluated by those similar results reported in the literature and with other commercial F.E. code under different boundary conditions. Furthermore, for specific values considered for distribution of fiber volume fraction and under various boundary conditions, computed minimum axial buckling loads of this composite cylindrical shell with variable volume fraction of fiber are compared with the traditional one in which the volume fraction of fiber is constant throughout the structure. Although average volume fraction and the layer fiber orientation are the same in both configurations, numerical results show that the appropriate variation of fiber volume fraction can result in increase of minimum buckling load of the shell.

Axial Buckling, First Order Shear Deformation Shell Theory, Fiber Reinforced Composite, Finite Element Method, Variable Fiber Volume Fraction