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

在“陶瓷3d结构的机器铸造：微观和宏观结构的实验研究和数值模拟”项目的扩展期间，项目合作伙伴FAU和IWM的先前工作将继续进行。在FAU已经成功开发和打印了各种robocasting paste之后，现在需要生成功能更复杂的3D结构，例如auxetic structures。使用新设计的狭缝喷嘴可以实现多层体系。这将与所谓的多材料印刷相结合，多材料印刷可以将不同的材料组合在一起，从而实现不同的材料性能。这些实验结果将与IWM的模拟结果进行比较。到目前为止，在项目中已经分析了血小板含量对膏体随时间变化的干燥行为的影响。这些结果现在应加以扩展，所谓的临界裂纹形成膜厚度应通过改变干燥膜的厚度来确定。这些研究结果将有助于项目合作伙伴IWM在微观结构水平上模拟干燥过程。在弗劳恩霍夫IWM方面，有两个主要目标。FAU实验表明，浆料中颗粒的取向对印刷长丝的力学性能有影响。通常采用Folgar和Tucker的数值模型来预测取向。然而，该模型的预测质量取决于一个未知常数。因此，第一个目标是根据现有的大量数据集建立确定该常数的一般规律。这个常数将用于优化过程，以获得更各向同性的粒子方向。第二个目标是描述印刷细丝的微观干燥过程。在干燥过程中，颗粒被重新定向，这可能导致由于应力的长丝开裂。这种重新定位在很大程度上还没有在数值和实验上得到探索。在模拟的帮助下，这一过程将在参数研究中进行研究。其目的是推导出一般有效的规则，作为粘贴和环境参数的函数的重定向量。

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.