Building end-use functional parts with additive manufacturing (AM) technologies is a challenging task. Several factors influence their surface finish, dimensional accuracy, mechanical properties and cost. Their orientation inside the building chamber is one of the most significant factors in AM processes. When using Fused Deposition Modeling (FDM) to build such parts, additional factors must be considered. This paper aims to accomplish two purposes: finding a good model to simulate FDM parts and correlating a finite element analysis (FEA) simulation with physical testing. The first objective was achieved by experimental tensile test of specimens to determine the nine mechanical constants that defines the stiffness matrix of an orthotropic material. Three Young’s modulus, three Poisson’s ratio and three shear modulus were experimentally obtained as well as yield tensile and ultimate strength of each specimen. A simple part was designed and manufactured in different orientations to be physically tested and simulated to achieve the second objective. Polycarbonate (PC) was used as part material. Combined loading including bending and torsion was used. Differences on mechanical response were observed during the physical test of the parts depending on the building direction. Conclusions comment results and the convenience of using a different constitutive model depending on the design and use specifications.