## 1 Introduction  
With the recent development in manufacturing techniques, smart materials become more effective at answering the requirement of highly advanced industrial applications. Those materials have the ability to react to external stimulations and can adapt their behavior according to the environment. This research constitutes a relatively recent area, which has emerged from the prospect of producing topologically optimized and complex shapes using additive manufacturing. In [1], [PERSON] defined a class of smart materials applied to additive manufacturing (AM) as follows: \"advanced structured materials, which are based on a static definition of complex shapes or a material's combination to achieve one or more properties that respond to a predefined functionality\". The concept of designing advanced structures by AM materials is widely applied to enhance structural performance and manufacture custom materials with specific functionality. For instance, [PERSON] et al. [2] worked on a toughening method of fracture properties using 3D printed topological patterns on a sample surface which effectively delayed crack initiation and deflected crack propagation. In a like manner, [PERSON] et al. [3] proposed an optimization method that uses continuous extrusion in 3D printing. It consists of an iterative procedure using re-meshing and analysis by finite element simulations. The proposed approach was applied to enhance the strength of a four-point bending beam made with Polylactic Acid PLA material. A new stress-based criterion for filament deposition in FFF FDM 3D printing has been suggested and tested [4]. The work reported herein is based on reproducing principal stress orientations in the sample to define the filament's trajectory deposition in the manufacturing process. It was inspired by the reinforcement principle of composite materials where the fibers are oriented toward the in-plane tensile stress. Experimental studies have reported that this \"enhanced\" deposition method tested on an Acrylonitrile Butadiene Styrene (ABS) material generates an improvement by over 20% of fracture toughness and leads to a ductile-like fracture behavior [5; 6; 7]. In the same spirit, [PERSON] et al. [8] developed a customized 3D printing tool-path for carbon fiber reinforced polymer where the carbon fibers reproduce the principal stress directions. This tool was used to print a spur gear geometry leading to a considerable improvement in the gear stiffness. The previously described deposition method has been proposed to surmount the problems caused by classical deposition methods such as layers alternation \(+45^{\circ}/-45^{\circ}\) or \(0^{\circ}/90^{\circ}\) raster angle orientation. In those configurations, a locally heterogeneous structure is created because of the weld lines and the residual air gaps between the deposed filaments. These trajectories do not necessarily respect the use requirements of the part since a misplaced weld line, considered as a weakness, can lead to the reduction of the structure's strength. Materials fabricated by fused filament fabrication (FFF) are supposed to exhibit strong anisotropy due to the filaments' orientation and the presence of an air gap [9]. Therefore, modeling their behavior will require a deep understanding of local phenomena occurring while loading the material. [PERSON] et al. [10] reveal the effect of the air-gaps size on the fracture morphology of the specimens announcing that larger air-gaps can cause inter-raster fusion bonds to fail which results in a more discretized surface area. In the study by [PERSON] et al. [11], a dual-notch void model was used to provide an explanation of the anisotropic tensile strengths of a 3D printed polymer. Most recently [12] [PERSON] et al. demonstrated that the interface between layers in 3D printed PLA material has isotropic strength equivalent to that of the bulk filament. This study suggested that the anisotropy is caused by the welding lines' geometries and a localized strain represented by a stress concentration.