Structural optimization of re-entrant negative Poisson's ratio structure fabricated by selective laser melting

Abstract

In this paper, a quantitative optimization of a modified re-entrant negative Poisson's ratio (NPR) structure whose overhanging struts were replaced with inclined ones to avoid the support structures which were generally required in the selective laser melting (SLM) process was carried out using finite element analysis (FEA) method. Poisson's ratios of models with inclined links of different strut inclination angles were calculated. The optimal simulated inclination angle of struts was 9° and the corresponding optimum re-entrant angle was 79° while the thickness of the strut was 0.9mm. The influence of fillet radii on Poisson's ratio and stress concentration was also discussed and the Poisson's ratio decreased and the stress concentration phenomenon remitted to some extent with increased fillet radii. In order to verify the improvement of the manufacturability of structures with inclined links, AlSi10Mg specimens were fabricated by SLM process using different scanning speeds and compression tests were also developed. Experimentally obtained results and simulation predicted ones were in good agreement. Therefore, the custom-tailor service could be accomplished in this way and the modified NPR structure with better surface quality could be obtained.