Micromechanical removal processes during material processing technologies with fluid-coupled particle systems

在这个项目中，固体颗粒系统和流体流动的相互作用在微机械尺度上研究了具有自由移动磨料颗粒的湿材料加工技术，如线锯、研磨或抛光。采用离散元法对三维锐边颗粒相互作用以及与可变形刀具或工件的相互作用进行了建模。模拟和量化了微观断裂过程对材料的实际去除机制。利用高速摄像机的立体显微镜，在专用实验装置上对剪切间隙和锯切缝中的现象进行了实验研究。该项目的目的是了解剪切流中颗粒系统与高速旋转表面相互作用的接触动力学，这受颗粒和壁面的粗糙度和材料特性的影响。在项目的第二阶段，我们将实验和数值研究重点放在粒子运动对流体流动的反馈上。这将在模拟中通过离散元法和流体求解器的完全耦合来实现。通过这种方式，这些影响就像静止的颗粒或颗粒团的流体干扰，流体中的局部压力变化以及颗粒的分离一样被捕获。基于已规划的基于边界条件明确的剪切流模型的基础研究，我们将开发的方法应用于硅片线锯技术，以建立与切除率和表面质量等宏观工艺参数的相关性。由于这些方法在材料加工技术中广泛应用，预计将显著提高效率和产品质量。

In this project, the interaction of solid particle systems and fluid flow is investigated on the micromechanical scale for wet material processing technologies with free movable abrasive particles as wire sawing, lapping or polishing. The interaction of sharp-edged three-dimensional particles among each other and with the deformable tools or workpiece are modeled by means of the discrete element method. The actual material removal mechanism caused by microscopic fracture processes is simulated and quantified. The phenomena in the shear gap and sawing kerf are experimentally investigated in special purpose built experimental devices by means of stereo-microscopy using high-speed cameras. The aim of the project is to understand the contact dynamics of particle systems in shear flows interacting with the surfaces at high velocities and rotations, which is affected by the roughness profiles and the material properties of particles and walls.In the second phase of the project we focus our experimental and numerical studies on the feedback of the particle motion onto the fluid flow. This will be achieved in the simulations by a complete coupling of the discrete element method and a fluid solver. In this way, such effects are captured like fluid interference by resting particles or particle clusters, local pressure variations in the fluid as well as separation of particles. Based on the planned fundamental research using a shear flow model with well-defined boundary conditions, we will apply the developed methods to the wire-sawing technique for silicon wafers to establish a correlation with the macroscopic technological parameters as removal rate and surface quality. Since these methods are widely distributed in materials processing technologies, a remarkable enhancement of efficiency and product quality are expected.