Collaboration in Modeling the Grinding of Silicon Carbide Fiber Reinforced Silicon Carbide Ceramic Matrix Composite

能够在高温下保持结构强度的先进材料对航空发动机和发电涡轮机的能效和可靠性至关重要。碳化硅纤维增强碳化硅(SiCf/SiC)是为这种高温应用而开发的新一代材料。使用金刚石磨料磨削是最终的精加工制造工艺，以达到零件的精度和表面完整性。在磨削过程中，金刚石磨料与脆性的SiCf/SiC材料之间的高速接触会产生表面裂纹，这将严重影响SiCf/SiC零件的强度和可靠性。由于增强纤维相对于块体材料的尺寸较小(直径约10微米)，使用传统方法很难对脆性复合材料进行建模，以隔离不发生断裂的工艺条件。本研究旨在验证用另一种建模方法来准确预测裂纹形成的可行性和局限性，并找到SiCf/SiC金刚石磨削的无损伤磨削条件。如果成功，该项目的建模方法可以应用于其他陶瓷增强材料，并增加服务于航空航天、国防和能源行业的美国制造公司的竞争力。这项研究将与德国RWTH亚琛大学磨削研究的国际领先机构机床和生产工程实验室以及美国的航空航天行业密切合作进行。虽然NSF只支持在美国进行的研究，但该项目使美国研究人员能够利用美国没有的研究设施，造福于美国的工业和制造业利益。参与该项目的学生将接触到国际视角，并在其他受尊敬的机构进行研究实践，以增强他们的劳动力准备。研究成果也将被应用到制造课程中，使更多的学生受益，并激励下一代工程师。本研究探讨了光滑粒子流体动力学(SPH)模拟方法对SiCf/SiC磨削过程中材料去除和损伤机理的模拟能力。将使用一个全面的实验计划来评估建模结果并隔离模型限制。SPH是一种基于粒子的无网格模拟方法，旨在解决以下技术难题：大的负前角切削角，金刚石颗粒的随机取向和分布，以及碳化硅纤维、纤维-基质界面和基质的大应变和高应变率变形和断裂。本论文首先通过实验和SPH模拟来研究SiCf/SiC单颗粒金刚石划痕，以确定碳化硅材料模型和SPH工艺。在此基础上进行了SiCf/SiC磨削的多颗粒实验和SPH模拟。通过对损伤机理的研究，确定了无损伤的SiCf/SiC金刚石磨削条件。总而言之，这项研究将推进现有的工具，以深入了解SiCf/SiC和其他陶瓷基增强复合材料在钻石划痕和研磨过程中的材料去除和损伤机理的基本知识。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Advanced materials which can maintain structural strength at high temperature are critically important for the energy efficiency and reliability of the aircraft engines and power generation turbines. The silicon carbide fiber reinforced silicon carbide (SiCf/SiC) is a new generation of material for such high temperature applications. Grinding using diamond abrasive is the final finishing manufacturing processes to achieve the part accuracy and surface integrity. The high-speed contact between the diamond abrasive and the brittle SiCf/SiC material during grinding may generate surface cracks, which will greatly affect the strength and reliability of SiCf/SiC components. Modeling brittle composite materials, to isolate processing conditions where fracture does not occur, is difficult using conventional approaches due to the small size of the reinforcing fibers (diameter about 10 microns) with respect to the bulk material. This research focuses on verifying the feasibility and limitations of using an alternative modeling approach to accurately predict the crack formation and find the damage-free grinding conditions for diamond grinding of SiCf/SiC. If successful the project's modelling approach can be applied to other ceramic reinforced materials and increase the competitiveness of US manufacturing companies servicing aerospace, defense, and energy industries. This research will be conducted in close collaboration with the Laboratory of Machine Tools and Production Engineering, an international leader in grinding research, at RWTH Aachen University in Germany, and aerospace industries within the US. While NSF is only supporting the research conducted in the US, this project enables US researchers to leverage research facilities not available in the US for the benefit of US industries and manufacturing interests. Students engaged on the project will be exposed to international perspectives, and research practices at other esteemed institutes enhancing their workforce readiness. Research findings will also be adopted in the curriculum of manufacturing courses to benefit a broad group of students and inspire the next generation of engineers. This research investigates the ability of the smoothed particle hydrodynamics (SPH) modelling approach to model and gain fundamental understanding of the material removal and damage mechanisms in SiCf/SiC grinding. A comprehensive experimental program will be used to evaluate the modeling outcomes and isolate model limitations. SPH is a particle-based, mesh-free simulation method developed to address technical challenges including the large negative rake angle cutting edge, random orientation and distribution of diamond grains, and large strain and high strain rate deformation and fracture of the SiC fiber, fiber-matrix interface, and matrix. The single grain diamond scratching of SiCf/SiC will first be studied through experiments and SPH modeling to identify SiC material models and SPH techniques. The multi-grain experiment and SPH modeling of the grinding of SiCf/SiC will then be carried out. The damage mechanisms will be investigated to isolate the damage-free diamond grinding conditions for SiCf/SiC. In summary, this research will advance the tools available to gain insights into fundamental knowledge of material removal and damage mechanisms in diamond scratching and grinding of SiCf/SiC and other ceramic matrix reinforced composites.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.