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于飞机发动机和发电涡轮机的能源效率和可靠性至关重要。碳化硅纤维增强碳化硅（SiCf/SiC）是这种高温应用的新一代材料。采用金刚石磨料进行磨削加工是实现零件精度和表面完整性的最终精加工制造过程。磨削过程中金刚石磨料与脆性SiCf/SiC材料的高速接触可能产生表面裂纹，这将极大地影响SiCf/SiC部件的强度和可靠性。对脆性复合材料进行建模，以隔离不发生断裂的加工条件，使用传统方法是困难的，因为相对于大块材料，增强纤维的尺寸很小（直径约10微米）。本研究的重点是验证使用替代建模方法准确预测SiCf/SiC金刚石磨削裂纹形成和寻找无损伤磨削条件的可行性和局限性。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，并提高美国制造公司为航空航天，国防和能源行业服务的竞争力。这项研究将与德国亚琛工业大学的机床和生产工程实验室（磨削研究的国际领导者）以及美国的航空航天工业密切合作。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无法获得的研究设施，为美国工业和制造业的利益服务。参与该项目的学生将接触到国际视野，并在其他受人尊敬的机构进行研究实践，以提高他们的劳动力准备。研究成果也将被纳入制造课程的课程中，以使广大学生受益，并激励下一代工程师。本研究探讨了光滑颗粒流体动力学（SPH）建模方法对SiCf/SiC磨削中材料去除和损伤机制的建模能力，并获得了基本的理解。一个全面的实验程序将用于评估模型的结果和隔离模型的局限性。SPH是一种基于颗粒的无网格模拟方法，旨在解决诸如大负前角切削刃、金刚石晶粒的随机取向和分布、SiC纤维、纤维-基体界面和基体的大应变和高应变率变形和断裂等技术难题。首先通过实验和SPH建模来研究SiCf/SiC的单晶粒金刚石划痕，以确定SiC材料模型和SPH技术。然后进行了SiCf/SiC磨削的多晶实验和SPH建模。研究损伤机理，分离出SiCf/SiC的无损伤金刚石磨削条件。综上所述，本研究将为深入了解SiCf/SiC和其他陶瓷基增强复合材料的金刚石刮擦和磨削过程中材料去除和损伤机制的基本知识提供工具。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值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.