Analysis and Sizing of Composite Anisogrid Cylindrical Structures without Skin

摘要

The focus of this work is sizing of cylindrical structures, using compositernanisogrid structural concepts and evaluating the efficiency of the grid concept withrnand without skin. The anisogrid structural concept was developed for wooden andrnmetal airplanes more than 60 years ago. Currently, anisogrid composite structures arernbeing evaluated for modern aircraft and space launch structures. Examples of thernanisogrid structural concept are shown in Figure 1.rnThis paper will describe the analytical sizing approach and failure analysisrnmethods for cylindrical anisogrid structure with and without skin. The anisogridrnconcepts without skin exhibit different failure methods than a grid structure where thernribs are supported longitudinally on one edge by the skin. Automated analysisrnmethods were implemented in the commercial sizing software HyperSizer to calculaternthe critical strength and buckling margin of safety of the grid stiffenerribs withoutrnskin. The analytical methods are verified against other published analytical modelsrnand with detailed linear and non-linear finite element models. The panel level ABDrnstiffness and local strain is verified with NASTRAN finite element models ofrnanisogrid panels without skin. After verifying the panel-level stiffness and local strainrnresponse, the analytically-computed global buckling Eigenvalue, computed usingrnRayleigh-Ritz SS8,is verified against a published analytical method and a linear, FEArnnumerical eigenvalue solution.