PSI - Issue 68

Büşra Eyri et al. / Procedia Structural Integrity 68 (2025) 332 – 338 B. Eyri et al. / Structural Integrity Procedia 00 (2025) 000–000

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stresses when exposed to a force in-plane direction (Günaydın et al. 2022). Honeycomb core designs have diversified to meet the needs of different applications. These include hexagonal, square, triangular, diamond, re entrant, etc. (Ma et al. 2021; Zhang et al. 2015). The two principal challenges associated with the utilization of sandwich structures are the high cost of production and the necessity for a durable bond between the core and the top layer (Lee et al. 2012; Wang et al. 2010). It is acknowledged that additive manufacturing techniques have established a novel domain within the manufacturing sector, facilitating the production of intricate structures that are challenging to produce through conventional means. These techniques are becoming increasingly pivotal in the creation of more complicated structures due to their benefits, including lower preliminary investment costs, reduced waste material, and comparatively shorter production times in comparison to traditional manufacturing methods (Wang et al. 2020; Yilmaz et al. 2023). For this reason, it is more straightforward and beneficial to obtain core structures designed for sandwich structures from 3D printers than from other manufacturing techniques. Furthermore, given that the layers and core can be manufactured using a single method, 3D printers are also crucial in terms of the strength that can be achieved. In order to achieve this, a number of studies have been conducted in which a variety of cell structures have been produced using the Fused Deposition Modelling (FDM) method, which is one of the additive manufacturing methods. FDM is a method based on the production of parts by the deposition of semi-molten polymer material from a heated nozzle (Tümer and Erbil 2021). In their study, Vyavahare and Kumar produced and compared honeycomb cell structures for PLA and ABS materials using the FDM method. The aim of this study was to investigate the relationship between the dimensional changes in cell structures and the compression properties (Vyavahare and Kumar 2021). A parallel investigation entailed the execution of low-speed impact assessments on structures created through the use of FDM with the incorporation of carbon fibre-reinforced composite (Hou et al. 2018). Also, Noel and colleagues employed both PLA and carbon-reinforced PLA in order to investigate the vibration and energy absorption properties of different cell structures (Noel et al. 2024). The objective of this study is to investigate the mechanical and vibration behaviors of the material and cell type on the structure. Thus, three different types of honeycomb cell structures, produced with PLA and ABS filaments, have been utilized: diamond (D), overexpanded (OX), and re-entered (R). The re-entrant cell type is a cellular structure with a negative Poisson's ratio, a property derived from its geometric configuration, which displays unconventional behavior. Such materials are called auxetic materials and, in contrast to classical material behavior, they exhibit a behavior that expands when stretched and contracts when compressed (Johnston and Kazancı 2021). The samples comprising the aforementioned cell types, produced via the FDM method, were subjected to three-point bending and vibration tests, and the outcomes were evaluated. 2. Material And Methods 2.1. Sample Production The test samples were produced via 3D printing with the use of Porima brand PLA (colored red) and ABS (colored blue) filaments with a diameter of 1.75 millimeters, using an Ender brand FDM type 3D printer. The production data for each material is presented in Table 1. The cell structures of the samples prepared with dimensions of 5x22x175 mm3 are shown in Figure 1.

Table 1. 3D Printing process parameters

PLA

ABS

Layer Height (mm) Nozzle Temperature [ ℃ ] Bed Temperature [ ℃ ] Infill [%] Print Speed [mm/s]

0.2 210 65 100 120

0.2 245 100 100 60