In this paper, a numerical method is proposed to simulate the mechanical behavior of a new polymeric pre-structured material manufactured by fused filament fabrication (FFF), where the filaments are oriented along the principal stress directions. The model implements optimized filament orientations, obtained from the G code by assigning materials references in mesh elements. The Gauss points are later configured with the physical behavior while considering a homogeneous solid structure. The objective of this study is to identify the elastoplastic behavior. Therefore, tensile tests were conducted with different filament orientations. The results show that using appropriate material constants is efficient in describing the built anisotropy and incorporating the air gap volume fraction. The suggested method is proved very efficient in implementing multiplex G code orientations. The elastic behavior of the pre-structured material is quasi-isotropic. However, the anisotropy was observed at the yield point and the ultimate stress. Using the Hill criterion coupled with an experimental tabular law of the plastic flow turns out to be suitable for predicting the response of various specimens.

Two evolutionary algorithms - the genetic algorithm and the evolution strategy - are compared in respect of mechanical design problems. Mechanical design problems are real world problems, characterized by a number of inequality constraints, nonlinear equations, mixed discrete-continuous variables and the presence of interdependent discrete parameters whose values are taken from standardized tables. The selection, recombination and mutation operators, and the chosen constraint-handling method are presented for both the genetic algorithm and the evolution strategy. In order to find the best combination of operators for each algorithm which will solve mechanical design problems, a number of selection and recombination operators are compared in respect of these problems. A comparison of these two algorithms with regard to three mechanical design problems extends the results of comparisons presented in the literature for unimodal and multimodal test functions with continuous variables only, and without constraints.