###### Abstract  
This study aims to investigate the mechanical properties of Functionally Graded Lattice Structures (FGLSs) and to determine their industrial application possibilities through additive manufacturing. For this purpose, lattice structures with uniform and horizontal, vertical and radially graded configurations are designed using auxetic unit cells were fabricated with RGD/20 photopolymer resin using Material Jetting. FGLSs are compared with uniform structures in regards with deformation behavior, structural strength and energy absorption. The results showed that the most significant deviation in the strut diameters of the uniform lattice structures was seen in the rotation lattice structure at 8.2%. The lowest deviation was seen in the chiral structure, which deviated by 5.4%. The lowest deviations (between 3.4% and 9%) in FGLSs were obtained in chiral structures. The highest relative density value (0.3049 g/cm\({}^{3}\)) among all configurations was observed in the vertically graded chiral structure. The lowest relative density value (0.1865 g/cm\({}^{3}\)) was obtained in uniform re-entrant structures. According to the compression test results, the highest compressive stress (2.61513 MPa) and elastic modulus (84.63192 MPa) were formed in the rotation structure. The maximum energy absorption capacity value (19.381 KJ) and the maximum specific energy absorption value (3649.905 KJ/kg) were obtained in the uniform chiral structure. keywords: functionally graded additive manufacturing; functionally graded lattice structures; computer-aided design; material jetting; mechanical properties +
Footnote †: journal: Applied Sciences  
Manufacturing (AM) technologies, which are at the forefront with the production of customized components, aim to gradually change the material organization in components by enabling the production of FGMs with controlled porosity [8]. The additive manufacturing of functionally graded materials gave rise to the term Functionally Graded Additive Manufacturing (FGAM). There are two different approaches for FGAM. In the first approach, gradient lattice structures are created by varying the printing parameters (laser power, laser speed, scanning range, etc. ), but this approach does not provide proper control of the porous structure at the microscale [9; 12]. In the second approach, CAD-based design, a series of unit cells are arranged in a specific order by shape, size and orientation to create gradient lattice structures in a controlled manner [9]. In this approach, Functionally Graded Lattice Structures (FGLSs) created with CAD software are structures in which the density of the structure is functionally graded instead of being uniform [13]. In contrast to uniform structures, the use of unit cells of varying sizes in FGLSs allows porous scaffolds to fulfil their function [1; 14; 15]. Recent studies show that the porosity of lattice structures can be graded by varying the strut thickness and size [16; 17; 18]. The strut diameters of the cellular units can be changed within the desired relative density range using different software in the FGLSs [13]. The relative density is the ratio of the density of the resulting lattice to the density of the base material [19]. In FGLSs, strut diameters and lengths, as well as unit cell sizes, shapes and orientations, can be varied to achieve a dimensional transition in porosity [13]. This allows gradient structures to be optimized for different applications and provides lower weight than uniform lattice structures with similar mechanical properties. The ability to design FGLSs to seamlessly transition using different unit cells can improve the overall mechanical performance of the structure. Overall, FGLSs offer a higher level of design flexibility and high performance compared to uniform lattice structures. In addition, FGLSs can be designed with progressive energy absorption features to increase their ability to withstand impacts and other high-energy loading conditions.