Robocasting of ceramic 3D-structures: experimental investigation and numerical simulation of micro- and macrostructures

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During the extension of the project "Robocasting of ceramic 3D-structures: Experimental investigation and numerical simulation of micro- and macrostructures" the previous work of the project partners FAU and IWM shall be continued.After FAU has already successfully developed and printed various robocasting pastes, functional and more complex 3D structures, such as auxetic structures, shall now be generated. The use of newly designed slit nozzles can enable multilayer systems. This shall be combined with the so-called multi-material printing, which enables a combination of different materials and thus different material properties. These experimental results will then be compared with the simulations of the IWM.The influence of the platelet content on the time-dependent drying behaviour of the pastes has been analysed during the project so far. These results shall now be extended and the so-called critical crack formation film thickness shall be determined by varying the thickness of the drying film. The results of these investigations will help the project partner IWM to simulate the drying process at microstructure level. On the part of Fraunhofer IWM there are two main goals. Experiments from FAU showed that the orientation of the particles in the paste has an influence on the mechanical properties of the printed filament. The numerical model of Folgar and Tucker is usually used to predict the orientation. However, the quality of the prediction of this model depends on an unknown constant. The first goal is therefore to establish a general law for the determination of this constant based on a large existing data set. This constant will then be used to optimize the process to get a more isotropic particle orientation.The second goal is to describe the drying process on the microscopic level of the printed filaments. During the drying process, the particles are reoriented, which can cause cracking of the filament due to stress. This reorientation is largely unexplored both numerically and experimentally. With the help of simulations, this process of reorientation will be investigated in a parameter study. The aim is to derive generally valid rules for the quantity of reorientation as a function of paste and environmental parameters.