Mechanical Properties of Some FDM 3D-printed Infill Structures

Abstract

Master thesis documents tensile test of fused deposit modeling 3D-printed parts. Infill configurations that’s investigated is line- and grid-pattern with 100% infill density for line pattern. Grid pattern have been printed with 20% and 40% infill density. To predict mechanical properties of 3D-printed parts with line pattern, classical laminate theory is chosen as mathematical model. Performing classical laminate theory calculations, the local mechanical properties of a layer must be determined. This is done by performing three tensile test and the resulting tensile modulus is used in classical laminate theory. Calculations is done with classical laminate theory and compared against a tensile test. The results from classical laminate theory and tensile test shows that classical laminate theory is a good method to determine mechanical properties of fused deposit modeling 3D-printed parts. Analytical method used for grid pattern is cellular solid theory. For comparison between cellular solid and experimental results there was done with two tensile test. One with 20% and the other one with 40% infill density. Predicted tensile modulus with the use of cellular solid was not deemed a decent prediction compared to the resulting tensile modulus from tensile testing. Test equipment was design with testing of material with higher tensile modulus than fused deposit modeling 3Dprinted parts has. Stress-strain curve was not as a continuous curve to where calculation of tensile modulus would be correct. Other factors that has an impact on prediction is manufacture of grid pattern with 3D-printers, and which solid tensile modulus should be used in predicting mechanical properties with cellular solid theory. In summary the use of cellular solid theory for fused deposit modeling 3D-printed parts is inconclusive.