Özet:

In this study, honeycomb structure with positive Poisson ratio (PO), re-entrant structure with negative PO, hybrid structure which is a combination of honeycomb and re-entrant structure and finally chiral structures were produced from PLA material by fused deposition modelling (FDM). Then, the effects of rib thickness and direction of the unit cell on the mechanical performances of these cellular structures were investigated experimentally in tension and compression conditions. As a result of tension and compression tests of cellular structured which are manufactured by FDM method, their elasticity modulus (EM), tensile strength (TS), compression strength (CS), absorbed energy (AE) and specific absorbed energy (SAE) were determined besides their Poisson ratios (PR). In addition to these findings obtained via mechanical tests, the hardness values and surface roughness values of the produced cellular structured samples were also measured. According to the results, it was determined that the direction and rib thickness of the unit cells in cellular structures significantly affect the mechanical performance of the cellular structures. While the TS and CS of the cellular structures increase with increasing rib thickness, the surface roughness and hardness values were measured as 14 µm and 75 Shore D, respectively. Although negative PO was observed in re-entrant, chiral and hybrid structures depending on the amount of deformation, positive PO was observed in honeycomb structures as expected. B thickness 0.5 mm and unit cells of the honeycomb structure (Hy 0.5) and the re-entrant structure (Ry 0.5) facing the y direction have the maximum AE and SAE values in tension and compression conditions, respectively. In addition, honeycomb structure and re-entrant structure have rib thickness of 0,5 mm and unit cells on y direction (Hy 0,5 and Ry 0,5) presents maximum AE and SAE values in order of tension and compression cases.

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