Additive manufacturing of over-expanded honeycomb core lattice structures and their characterization

Date

2024-9-4

Author

Şimşek, Tuğba

Metadata

Show full item record

This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.

Item Usage Stats

48
views

70
downloads

Cite This

Experimental and simulation analyses of the lattice structures resembling an over-expanded honeycomb core material were performed for different parameters for unit cells of the structures. In the first part of the thesis, the lattice structures produced using an Additive Manufacturing (AM) method resembling an over-expanded honeycomb core material were examined regarding their mechanical properties across various parameters. Although the size of the samples or test specimens are kept the same, the unit cell sizes and parameters were changed. Test specimens were designed according to three different cell sizes, three different thicknesses of cell edges and three different cell angles. Therefore, 27 different planar lattice structures were designed, and 5 samples were manufactured for each of the 27 different lattice structures by 3D printer using the Fused Deposition Modelling (FDM) method. Polylactic acid (PLA) was preferred for manufacturing the test specimens, because it is frequently used in literature, is easily available, and is an environmentally friendly material. All the test specimens were subjected to compressive load and parameter changes’ effect on mechanical properties such as yield strength and Young’s modulus were analyzed. In the second part of the thesis, FE analyses of the same test specimens were performed. Different from yield strength and Young’s modulus, Poisson’s ratios of the specimens were calculated by using FE analysis. According to the results, experiments and the FE models give similar outputs. One of the outputs is that decreasing the cell size and increasing the thickness of the cell edges enhance the strength of the lattice structures for each cell angle. The second of the outputs is that increasing the angle also increases the strength and Young’s modulus. The last one of the outputs is that the structures with 0° and 90° angles of the unit cells show auxetic features, whereas the structures with 45° angles of the unit cells show non-auxetic features.

Subject Keywords

Lattice structures, Over-expanded honeycomb core material, Auxetic structures, Additive manufacturing, Poisson’s ratio

URI

https://hdl.handle.net/11511/111373

Collections

Graduate School of Natural and Applied Sciences, Thesis