PSI - Issue 47

Andre Hartawan Mettanadi et al. / Procedia Structural Integrity 47 (2023) 168–175 Mettanadi et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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Do et al., 2022; Nubli et al., 2022; Prabowo et al., 2020; 2021; 2022; Widiyanto et al., 2022). In recent years, single cell structures have been studied extensively, i.e., polygonal, square, triangular, and metallic hybrids. Various researches have been done to improve the performance of crashworthiness, such as in terms of explosion loading by Ansori et al. (2022) and Mubarok et al. (2022), ballistic impact by Alwan et al. (2022), hard grounding by Prabowo and Bae (2019), and ship-ice collision by Gagnon and Wang (2012). A large number of studies have shown that increasing the number of cells in a thin-walled tube can greatly increase the energy dissipation capacity. Kim et al. (2002) proposed a new multi-cell box configuration by optimizing the distribution of box elements in corners. The results show that the crashworthiness of the new multi-cell profile is nearly double that of the original structure. The triangular tube was added by Vinayagar and Senthil (2017) into the circular tube to form a double section multi-cell column, which exhibits a more stable deformation pattern than the traditional single-cell structure. Optimization of the configuration of the multi-cell tubal structure was carried out by Sun et al. (2018). Compared with the original tube, the optimized results show great advantages in energy absorption under axial impact conditions. The above studies confirm the performance advantages of multi-cell structures over single-wall columns of multiple points, but their energy utilization efficiency still has the potential to be further improved. Therefore, this research focuses on improving the performance of multi-cells with a hexagonal concave shape and is limited by circular tubes . 2. Literature Review The most commonly applied crashworthiness indicator is the force transfer diagram as shown in Figure 1, which displays the ratio of the crushing force to the shortening of the thin-walled profile strength (PCF) and specimen shortening during the crushing process, which provides a basic representation of the development of energy dissipation Rogala et al., (2020). Tarlochan et al. (2013) describes the peak force, F max and energy absorption (EA) in a thin walled structure subjected to axial and oblique impact forces. The peak force of a component is the highest load required to cause significant permanent deformation, and in the simulations, the peak load is measured from the reaction force at the fixed base.

(a) (b) Figure 1. Diagrams of the related terminologies in impact: (a) force - displacement curve (Rogala et al., 2020), and (b) specific energy absorption to displacement curve (Liang et al., 2022). Cylindrical cross-section tubes will be used to investigate energy absorption and axial deformation resulting from axial compressive loads. Energy absorption can be obtained by first calculating the reaction force/crushing load. Typical failure modes for square tubes performed by Abramowicz et al. (1986) are provided to predict the reaction force/crushing load. Higher energy absorption efficiency of materials is shown from higher specific energy absorption (SEA) values as seen from Equation 1. Specific energy absorption (SEA) is derived from the calculation of absorbed energy per unit mass of the structure as: