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Talks and Poster Presentations (without Proceedings-Entry):

J. Stögerer, S. Baumgartner, A. Hochwallner, J. Stampfl:
"Bio-Inspired Toughening of Composites in 3D-Printing";
Talk: ESIAM, Trondheim; 09-09-2019 - 09-11-2019.



English abstract:
Natural materials achieve exceptional mechanical properties by relying on hierarchically structuring their internal architecture. In several marine species, layers of stiff and hard inorganic material are separated by very thin compliant organic layers granting them both stiffness and toughness. The underlying phenomenon providing these exceptional mechanical properties is called shielding effect and is based on the periodical variation of Young´s Modulus. A crack propagating through the material is arrested inside a softer layer and further spreading is hindered or prevented. Applying this concept to 3D-printing, inherently brittle polymer composites built in a stereolithography (SLA) process are adapted. A hybrid 3D-printing device combining SLA and inkjet printing structures samples of two different materials in a layer-wise manner. Both components used in this system, the ink for jetting and the resin for structuring by SLA, are acrylate-based and photo‑curable. Pure materials (i.e., resin and ink) show a significant difference in Young´s Modulus, thus satisfying the requirement of strongly varying mechanical properties. Three different groups of composites are produced to analyse the impact of material alteration. One group solely consisting of resin material (i.e. control group 1), one group with alternating layers of resin and ink (i.e. hybrid material), and one group consisting of resin and ink without spatial separation of the two materials (i.e. control group 2). Measurements reveal an increase in fracture toughness and elongation at break as well as a decrease in Young´s Modulus for hybrid material samples compared to both control groups. Moreover, mechanical tests show now significant differences between the control groups. Thus, the toughening effect is essentially dependent on different materials being well contained within separated layers.

Keywords:
3D-Printing, Bio-inspired, Composites, Stereolithography, Inkjet Printing

Created from the Publication Database of the Vienna University of Technology.