PSI - Issue 21

E.F. Akbulut Irmak et al. / Procedia Structural Integrity 21 (2019) 190–197 E. F. Akbulut Irmak et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Figure 7. Undamaged surface of a specimen

5. Numerical Results Numerical studies were performed with fully integrated solid elements with an element-length of 0.25 mm in LS Dyna. In a study carried out by Tancogne-Dejean et al. (2019), the pores were introduced by randomly deleted whereas Brinson et al. (2006) assumed pores as very low modulus in 3D finite element analysis. Similar approach were implemented in the present study and voids were modeled with low modulus of 21 GPa. The percentage of void elements is approximately 5% of all elements. Although building orientation highly effects the ductility of SLM AlSi10Mg as-built parts, in general material shows ductile behavior, Kempen et al. (2012). Nevertheless, this material shows brittle-ductile behavior in uniaxial tensile and brittle behavior in notched specimens in the current study. In order to characterize a material accurately, it is important to determine a material model, which can capture each deformation behavior well. Ductile material model with damage properties can capture brittle-ductile behavior; however, this is not possible with a brittle material model in the contrary situation. Thus, *MAT_CAZACU_BARLAT (*MAT_233) was implemented in the numerical studies. Hockett-Sherby hardening curve was determined by the inverse parameter identification. To simulate the elongation at break, GISSMO was applied. Figure 8 shows the experimental and numerical results in comparison. As seen in the simulation results, elongation at break were predicted better with models including voids. Material characterization studies were carried out for the lowest ductility case of experimental data and the same experiments were considered for the comparison. As seen in the figure, there is a good correlation between test and numerical model.

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Figure 8. Simulation results; a) uniaxial and b) notched