Anisotropic Mechanical Properties of Lattice Grid Composites

According to the equivalent continuum method and coordinates transformation, the anisotropic properties of the stiffness and the strength of planer lattice grid composites were researched. Anisotropic properties of various lattice grid composites with three to five stacks of struts were discussed and compared. The criteria of stiffness isotropy and orthotropy were concluded. Ordinarily, the grid stiffness is anisotropic. But with two or four symmetries the lattice is orthotropic and quasi-isotropic with at least six symmetries. The initial yield or brittle failure strength of typical lattice grid compoaites was studied and compared. The strength of the lattice grid composite is always anisotropic, even if their stiffness is quasi-isotropic. The degree of anisotropy of the strength is normally stronger than the stiffness anisotropy. With more symmetries, more bar rows and more uniform equivalent rigidities of struts, the variation of the strength gets smaller.