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

在“陶瓷三维结构的机器人铸造：微观和宏观结构的实验研究和数值模拟”项目的扩展过程中，FAU和IWM项目合作伙伴的先前工作将继续下去。FAU已经成功地开发和印刷了各种机器人铸造浆料，现在应该生成功能更复杂的三维结构，如伸展结构。使用新设计的狭缝喷嘴可以实现多层系统。这应与所谓的多材料印刷相结合，多材料印刷使不同的材料组合在一起，从而使不同的材料性质不同。这些实验结果将与IWM的模拟结果进行比较。到目前为止，在该项目中已经分析了血小板含量对糊状物随时间变化的干燥行为的影响。现在应扩展这些结果，并通过改变干燥膜的厚度来确定所谓的临界裂纹形成膜厚度。这些研究的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。就Fraunhofer IWM而言，它有两个主要目标。FAU的实验表明，浆料中颗粒的取向对印花长丝的力学性能有影响。通常用Folga和Tucker的数值模型来预测取向。然而，这个模型的预测质量取决于一个未知的常数。因此，第一个目标是在现有大量数据的基础上确定确定这一常量的一般规律。然后，这个常数将被用来优化工艺，以获得更各向同性的颗粒取向。第二个目标是在微观水平上描述印刷长丝的干燥过程。在干燥过程中，颗粒会重新定向，这可能会由于应力而导致灯丝破裂。这种重新定位在很大程度上还没有从数值和实验上进行探索。在模拟的帮助下，这一重定向过程将在参数研究中进行研究。其目的是推导出作为糊剂和环境参数的函数的重定向量的一般有效规则。

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.