PSI - Issue 28

Fuzuli Ağrı Akçay et al. / Procedia Structural Integrity 28 (2020) 1399– 1406 Author name / Structural Integrity Procedia 00 (2019) 000–000

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the order of millimeter or micrometer (Ashby, 2016). Although conventional manufacturing processes of lattice structures in advanced applications are complex, inefficient and expensive, additive manufacturing (or called 3D printing) overcomes these difficulties (Maskery et al., 2016). Additively manufactured lattice structures are used in various engineering applications, particularly in aerospace and automotive industries as well as biomedical applications, due to their high strength to weight ratio and excellent energy absorption capacity. A traditional way to examine the response of lattice structures subjected to external loading is to perform experimental research and/or to employ numerical investigation. In other words, a theoretical model to analytically determine the strength of micro lattice structures is lacking. Therefore, in this study, an analytical model is developed utilizing limit analysis to predict the strength of micro lattice structures. Analytical results are compared to the experimental results of additively manufactured AlSi10Mg lattice structures by selective laser melting (SLM). Moreover, 2D and 3D finite element simulations are conducted in order to validate the experimental results as well as to investigate the accuracy of the analytical model. The remainder of the article is organized as follows. A brief overview of the experimental results are presented in Section 2. The analytical model is developed in Section 3 and the numerical investigation is presented in Section 4, including the discussion of the results. Finally, a summary with conclusion remarks is given in Section 5. Nomenclature unit cell size in each direction Young’s modulus strut diameter total (applied) load � collapse load L beam length in half-cube model, i.e., half the strut length L full plastic moment L number of cells in each direction L strut/rod radius L beam displacement L angle between a strut and the horizontal plane L yield strength L relative density of a lattice L lattice strength L Poisson’s ratio 2. Experimental Results Six different unit cell configurations were utilized in the experiments: Cubic vertex centroid, cubic diamond, cubic fluorite, tetrahedral octahedral edge, tetrahedral octahedral vertex centroid, and tetrahedral vertex centroid. The unit cell configurations are shown in Fig. 1. Four micro lattices with different number of unit cells and different strut diameters were fabricated, i.e., twenty-four AlSi10Mg micro lattices were designed and fabricated (Yu et al., 2019).