Micromechanical buckling analysis of soft lattice metamaterials accounting for randomly distributed imperfections

This paper investigates the mechanical performances of soft lattice metamaterials composed of beam-like periodic arrangements. Particularly, the effect of geometric defects, caused by the manufacturing processes on the nonlinear buckling response, is analyzed with the final aim of artificially designing the imperfections to drive buckling loads and collapse shapes. To this end, the lattice structures are modeled as the assembly of shear-deformable finite element beams under nonlinear geometric assumption. Firstly, the linear buckling modes are evaluated with reference to the perfect ideal material and, then, these are used to construct the model of the imperfect lattice structures by applying an ad hoc procedure that accounts for the randomness of the geometric imperfections. Sensitivity analyses are performed to evaluate the influence of several factors, such as boundary conditions, scale effect, maximum imperfection size and buckling modes considered to generate the imperfect structures.