NSF Young Investigator: Formal Tolerance and Set-Based Methods in Engineering Design and Manufacturing

该项目侧重于在学术研究项目、工程教育和工业应用之间取得平衡。在本课程中，将讨论工程设计和制造设计的一般问题。特别是，研究计划的一部分考虑了用于确定材料去除过程和固体自由形式制造所产生的物理表面结构的分析和实验模型的发展。这些模型的基础是基于分形的表示法，或者更广泛地说，卡尔胡宁-洛夫法，它将提供将制造过程变量与设计参数联系起来的指标。虽然已知基于分形的方法适用于表面光洁度，但本研究中将确定的表面结构是公差尺度(例如，径向轴承的40-300微米)。公差通常带有设备的功能。例如，在旋转机构中，轴和轴承组件之间的公差可能是关键的，即，如果轴-轴承组件未对齐或超出公差，系统将因过度磨损和可能的卡住而导致灾难性故障。提供将制造过程变量与设计参数、性能参数和功能要求联系起来的设计方法和措施是至关重要的，特别是如果要在设计的早期阶段将制造信息与功能考虑相结合的话。这项研究将寻求通过实验来验证基于分形的模型，将结果表示在正式的基于集合的理论中用于设计，并将该方法应用于旋转机械、结构和微自动化。除了分形公差和基于集合的设计表示的基本理论之外，还将开发用于将全局几何信息与制造技术的设计相联系的计算方法。这些计算方法的一般范围将是基于特征的设计系统，包括空间关系的正式表示。

This project focuses on a balance between an academic research program, engineering education, and industrial applications. In this program, the general problems of engineering design and design for manufacturing will be addressed. In particular, one part of the research program considers the development of analytical and experimental models for determining the physical surface-structures produced from both material removal processes and solid-freeform fabrication. The basis for these models is fractal-based representations, or more generally the Karhunen-Loeve method, which will provide indices for linking manufacturing process variables to design parameters. While a fractal-based approach is known to be applicable at surface finish scales, surface structures that will be identified in this research are at tolerance scales (e.g., 40-300 microns for journal bearings). Tolerances usually carry the function of the device. For example, in a rotating mechanism, the tolerances associated between a shaft and a bearing assembly may be critical, i.e., if the shaft-bearing assembly is misaligned or out-of-tolerance, catastrophic failure of the system will result due to excessive wear and possible seizure. Providing design methods and measures that link manufacturing process variables to the design parameters, performance parameters, and functional requirements of a design is crucial, especially if manufacturing information is to be combined with functional considerations in the early stages of design. This research will seek to verify the fractal-based models with experimentation, represent the results within a formal set-based theory for design, and apply the method to rotating machinery, structures, and microautomation. Beyond the fundamental theories of fractal tolerances and set-based design representations, computational methods will be developed for linking global geometric information to the design for manufacturing techniques. The general scope for these computational methods will be a feature-based design system, including the formal representation of spatial relationships.