Investigation of the mechanical properties of honeycomb sandwich composites produced by 3D printer

Honeycomb composite sandwich structures are preferred because they are light and have high impact and compression strength compared to their weight. In addition, it is used in many sectors such as automotive, aircraft, light commercial vehicle, yachting, high-speed train, construction, packaging, wind energy, solar panels due to its many usage features such as being resistant to chemicals and water, screwing, drilling, adding, and repairing depending on the material produced. Sandwich structures are composite building elements that consist of bonding a core structure between the bottom and top face sheet. Face sheets are thin, solid and dense. The core is thicker than the face sheet and lower density materials are preferred. There are many studies available for sandwich structures to have mechanical properties such as compression, impact and bending strength, and they continue to be researched and developed. Within the scope of the thesis, cores from polylactic acid (PLA) filament were produced in a 3D printer using honeycomb geometries with three different cell widths and cell wall thicknesses. The mechanical properties of single-layer and two-layer sandwich composites, of which the produced cores are bonded with carbon fiber reinforced composite plates (CFRP) on the lower and upper face sheets, were investigated by experimental methods. Honeycomb geometries with three different cell widths and cell wall thicknesses of 6_0.8 mm, 9_1.2 mm and 12_1.6 mm, respectively, were used in the study. In order to obtain equal surface area, these dimensions were preferred by increasing both cell width and cell wall thickness. Two-layer samples were produced from core with each solid having the same and different (hybrid) cell widths. Three-point bending, low speed impact and compression tests were applied to the samples with three different cell widths but close to each other surface areas. With the graphics obtained from the tests, the behaviors of the samples against the tests were examined and comments were made. In the compression tests, the compressive strength of the single-layer and double-layer samples with a cell width of 12 mm was found to be high. In the bending tests, the highest bending stiffness was determined in single-layer and double-layer specimens with a cell width of 6 mm. It was determined that samples with 6 mm cell width performed better in low-speed impact tests applied at three different energy levels (80J, 100J and 140J).