Optimal design concepts for flat isogrid and anisogrid lattice panels longitudinally compressed

The interest on composite anisogrid lattice structures as the baseline design concept for lightweight applications is increasingly growing. The potential weight efficiency of such concept is based on the proper design of the system of ribs, their orientation and cross-section. Although several analytical and numerical works are devoted to cylindrical and conical lattice shells axially compressed, no similar studies support the preliminary design phase of anisogrid flat panels without the skin. For this reason, the paper is focused on the formulation of the main design constraint equations valid for anisogrid lattice panels longitudinally compressed, in which local and global buckling failure modes are dominating, and on the consequent approach to minimum mass solutions through the analytical minimization of corresponding safety factors. Thus, approximate closed form solutions are developed to explore the general anisogrid case and the specific isogrid configuration due to its widespread use. Static stiffness properties of lattice panels are also included in this study in order to satisfy additional requirements other than strength. An application of this method is finally proposed showing a very good agreement with finite-element results.