Efficient Modelling of Chip Formation in Orthogonal Cutting Based on Isogeometric Analysis and Modern Methods for Material Characterization

该项目考虑了切屑形成的数值模拟及其估计切削过程工艺参数的潜力。基于有限元法的切屑形成数值模拟也可在商业软件中使用，是预测切削中复杂热机械效应的常用方法;特别是在切削刃附近。然而，现有技术显示出局限性，即，一方面，实际切屑形成模拟仅允许表示非常短的工艺序列，另一方面，其基础模型的有效性有限;特别是在定量预测工艺值（例如力、应力、应变、温度和切屑形状）方面。这些限制部分是由于材料和摩擦模型不足，然而，有明确的证据表明，所使用的有限元网格（细化，元素类型，元素变形和方向）不仅对数值结果的准确性有很大的影响，而且对可以捕获的一般现象。这尤其包括剪切带的发展。这些依赖关系将通过使用现代数值方法来解决，即等几何分析（伊加）和时空有限元。拟议项目的具体科学目标是开发一种基于等几何分析和计算流体动力学中已经建立的变形空间域/稳定时空（DSD/SST）方法的切屑形成现代数值分析工具。新工具将在效率和准确性方面进行评估，特别是在主要和次要剪切区域以及工件表面区域的影响。它必须得到现代材料表征方法的支持。在方法论方面，伊加的行为的理解时，提出了建模动态接触问题的材料方程。特别是显着减少的数值误差，这是通过重新网格化的步骤，预计将导致增加的数值精度。这构成了切屑形成模拟的重要步骤，并将立即提高其适用性。

The proposed project considers the numerical simulation of chip formation and its potential to estimate process parameters for cutting processes. Also available in commercial software, the numerical simulation of chip formation based on the finite element method is a commonly used approach to predict the complex thermo-mechanical effects in cutting; in particular in the vicinity of the cutting edge. However, the state of the art shows limitations, i.e. on the one hand the actual chip formation simulations permit only the representation of very short process sequences and on the other hand their underlying models are of limited validity; in particular in terms of the quantitatively prediction of process values such as forces, stresses, strains, temperatures, and chip shapes. These limitations are partially due to insufficient material and friction models, however, there exists clear evidence that the utilized finite element meshes (refinement, element type, element deformation and orientation) have a strong influence not only on the accuracy of the numerical result, but also on the general phenomena that can be captured. This includes in especially the development of shear bands. These dependencies are intended to be resolved via the use of modern numerical methods, namely isogeometric analysis (IGA) and space-time finite elements.The specific scientific aim of the proposed project is to develop a modern numerical analysis tool for chip formation based on isogeometric analysis and the in computational fluid dynamics already established Deforming-Spatial-Domain/Stabilized Space-Time (DSD/SST) method. The new tool is to be assessed in terms of efficiency and accuracy, in particular regarding effects in the primary and secondary shear zone, but also the workpiece surface zone. It has to be supported by modern methods of material characterization. On the methodological side, an understanding of the behavior IGA presents when modeling dynamic contact problems with thermodynamically coupled material equations. Especially the significant reduction of numerical errors, which are induced through remeshing steps, are expected to lead to an increase in numerical accuracy. This constitutes an important step for chip formation simulation and will immediately improve its applicability.