Determination of stiffness coefficients and buckling strength of composite lattice conical shells using shell fiber path and lattice rib analysis

In this paper, using fiber path geometry, shell geometry, lattice geometry and classical shell theory, the stiffness coefficients of a composite conical shell and a composite lattice conical shell are obtained. The results in determining the buckling strength in this method have been compared with the experimental results and a good agreement has been seen between the results. The stiffness coefficients are obtained as a function of the position of each point of the shell relative to the axis of the conical shell generator. The value of all stiffness coefficients at each point of the unreinforced shell relative to its generating axis decreases from the location of the small edge to the location of the large edge of the conical shell. Changes in the thickness of the shell and the angle of placement of the fibers on the shell relative to the axis of the cone generator cause the stiffness of the shell to vary along the axis of the generator. Therefore, the stiffness of the whole conical lattice structure varies in the direction of its generator. It can be seen that although the analysis of the buckling strength of the conical shell by the equivalence method is not completely accurate, but it provides a detailed description of the manner and ratio of changes in stiffness of the lattice shells along the axis of its generator. The coefficients equivalent like the coefficients of a filament wound composite laminated conical shell vary by the direction of its generating axis.