Mechanical behaviour of polymeric lattice structures produced by additive manufacturing

2022-11
Kalaycıoğlu, Şükrü Güray
Additive manufacturing (AM) is a manufacturing method based on the layer-by-layer deposition of the desired geometry. Polymer AM provides means to produce compliant polymeric structures for impact-absorbing applications. The recent introduction of foaming elastomeric filaments opened a new design space for achieving optimized impact absorbance performance. This thesis investigates this route through the mechanical testing of solid and cellular polymer foam structures produced by additive manufacturing. The experimental work in this thesis employs Fused Filament Fabrication (FFF), which is a cost-effective AM technique for the rapid manufacturing of complicated geometries in low quantities. Recent advances in filament technology have enabled the production of foaming thermoplastic polyurethane (TPU) filaments, which makes the printing of microporous polymeric structures possible through the FFF method. The first part of the thesis investigates the mechanical properties of the TPU foam produced by FFF. The systematic experiments show that the nozzle temperature directly influences the foaming behavior. With increasing temperature, the extent of foaming increases, which results in a decrease in the elastic modulus and strength. The second part of the thesis investigates the impact-absorbing performance of honeycomb lattice structures produced by the same foaming TPU. The experiments show that as the nozzle temperature increases, the energy absorption capacity and the peak stress of the lattice structure increase. Overall, the results demonstrate the great potential of foaming filaments in achieving unique impact-absorbing behavior. Future work will focus on understanding the behavior of different cellular structures and lattice geometries made of TPU foams under load.

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Citation Formats
Ş. G. Kalaycıoğlu, “Mechanical behaviour of polymeric lattice structures produced by additive manufacturing,” M.S. - Master of Science, Middle East Technical University, 2022.