Abstract
This chapter aims to briefly review the main theoretical and finite element simulation results on the elastic properties and yield strengths of regular hexagonal honeycombs, Kelvin open cell foams, random irregular Voronoi honeycombs and open-cell foams, and discuss about their deformations mechanisms. The book chapter further introduces the effects of other parameters such as the degree of cell regularity, imperfection of defects, cell size, solid volume fraction and material distribution, on the elastic properties and yield strengths of these cellular materials. Voronoi honeycombs and open cell foams can be related to their mechanical properties.