The development of additive manufacturing processes, which one of their advantages is the ability to generate complicated geometries, has introduced new capabilities in industrial applications. One kind of these capabilities is the use of cellular lattice structures as a way to decrease manufacturing costs, to control the mechanical properties of parts, and to achieve desired design specifications for a special problem in this area. The benefits of lattice structures have led researchers to introduce and study new lattice structures. Cellular lattice structures include two-dimensional structures, Voronoi, TPMS, strut, node-based, and custom unit cells, each of which has many subsets. Thus, selection of the appropriate structure for each unique design is an important challenge that should be addressed. In previous related works, different criteria have been eva‎luated to study these structures; however, some other specifications have not been studied thoroughly. In addition, previous researchers have usually used limited lattice structures. In this research, by studying a large group of lattice structures using different analytical and experimental methods, it is attempted to find a proper algorithm for determining the best structure with desired tensile module and high strength-to-weight ratio. To do so, different design methods for all of the lattice structures were studied because the algorithmic design of a structure makes the design of the others or new ones possible without wasting time or extra costs. Thus, the current research is the first one that tries to solve the issues related to all categories of lattice structures and even the design of gradient, composite or hybrid-gradient structures. Moreover, in the present work, the Young’s module of eighteen various structures are extracted using the design approach and algorithmic analysis, inspired by the Gibson-Ashby correlation. To do this, experimental and homogenization methods are employed for calculating Gibson-Ashby coefficients. After that, to eva‎luate them, some other structures' behavior were predicted. The results showed that, although the homogenization is not a precise method, its accuracy suffices for comparison purposes. This means that, if the homogenization methods predict more tensile dominancy in structure A compared to structure B with the same density, the experimental tests will show the same result. It is worth mentioning that the Gibson-Ashby correlation is a power-law relation so it can predict the structures with power-law behaviors better than other structures. Another important point is that with the increase in relative density between two bending-dominant and tensile-dominant structures, their behaviors of them will reach closer to each other. It should be considered that although the manufacturing process, the material, and other conditions affect the mechanical properties, the resulted relation in this study can predict 105 the tensile-dominancy in structures manufactured by other methods. Finally, based on the results, the most proper structure for getting desired tensile module and high-strength to weight ratio is the honeycomb structure if the loading is perpendicular to the hexagon plane. It should be mentioned that the algorithm proposed in this research offers the possibility of studying other structures based on different goal functions. Keywords: Lattice structures, Additive manufacturing, tensile-dominant, bending-dominant, Gibson-Ashby Correlation

محسن بدرسماي، محمود كدخدائي

احسان فروزمهر

مهدي كاروان، عباس قائي