<p>The cellular structure is an assembly of cells. With the cellular structures, the mechanical properties can be varied by changing the shape of the cells. It may have excellent properties such as lightweight, high rigidity, and high energy absorption by artificially manufacturing the cellular structure. Owing to the development of additive manufacturing technology in recent years, a number of research about artificially manufactured cellular structures has been carried out. However, guidelines for designing cellular structures with desired properties have not been established. Therefore, this study aims to present the design guidelines for cellular structures with high energy absorption capacity. The unit cell was designed by topology optimization with the objective function of rigidity maximization. The compressive behaviors of the topology-optimized cellular structure and BCC, FCC lattice structures were investigated by carrying out the compression analysis by finite element method (FEM). The analysis was conducted both for unit cells and aggregations of cells. The effect of relative densities of the structure was also investigated. From the analysis results, it was shown that the deformation modes of the struts of the cell were different in optimized structure and lattice structures. It was revealed that the struts of the optimized structure were compressively deformed while struts of the lattice structures were deformed by bending. Since the struts in the optimized structure were compressively deformed, the plastic collapse stress was larger than lattice structures. Moreover, the shape of the stress-strain curve after the plastic collapse was different due to the difference in the deformation of the struts of the cell. The stress continued to increase after the plastic collapse with the optimized structure, while the plateau appeared with the lattice structures. Besides, some unstable deformation appeared when the relative density of the structures was small. With smaller relative densities, the optimized structure had a large buckling deformation after the plastic collapse, and the FCC lattice structure had an oscillation in the stress-strain curve due to the collapse of the cell in step. These unstable deformations affected the energy absorption capacities. Finally, the amount of energy absorption and the energy absorption efficiency of each structure were evaluated. The optimized shape had a much larger amount of energy absorption compared with the lattice structures, but the energy absorption efficiency is slightly poorer. Further study is necessary to examine the objective function and boundary conditions in topology optimization to design cellular structures with larger energy absorption capacity by controlling the stress-strain relationships.</p>

Finite Element Analysis on Plastic Collapse Behavior of Topology-Optimized Cellular Structure Subject to Compressive Loading

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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