Design of Contact-aided Compliant Mechanisms to Generate Sophisticated Motions

该赠款为开发接触辅助柔顺机构的系统优化设计方法提供资金。柔性机构是一种无关节的弹性结构，不仅在宏观和微观尺度上易于制造，而且在性能上上级传统的刚体关节机构。在该项目中，柔性机构的弹性连续体的不同部分之间的间歇接触被用来获得非平滑运动。在这项研究中要考虑的非光滑运动包括突然变化的斜率和曲率的路径跟踪的相关点的机制，以及力偏转特性。设计方法将通过利用边界条件的变化来开发，当机构上的一个点接触另一个点或刚性表面时，会导致机构的运动学和运动静力学的突然变化。机构的拓扑结构和形状以及机构附近的刚性表面将被设计用于期望的非光滑行为。基于大变形的非线性弹性分析、设计灵敏度分析和非光滑优化技术将被用于实现本项目的目标。本项目的成功完成将为实现单件柔顺机构的非光滑运动提供一般原则和系统的设计方法。该项目的预期目标之一是设计一种“顺应性曲柄”，该曲柄利用单个弹性结构将往复平移输入转换为连续的单向全旋转输出。它将对微尺度器件以及宏观尺度产品产生影响。在理论方面，在这项研究中开发的优化技术将有助于非光滑优化的一般领域。该项目的教育贡献之一将是在互联网上提供接触分析和非光滑优化代码，供学生，执业工程师和研究人员普遍访问。

This grant provides funding for developing systematic optimization-based design methodologies for contact-aided compliant mechanisms. Compliant mechanisms are joint-less elastic structures that are not only easy to manufacture at macro and micro scales but are also superior in performance to traditional rigid-body jointed mechanisms. In this project, intermittent contact between different portions of the elastic continuum of the compliant mechanism is utilized to obtain non-smooth motions. Non-smooth motions to be considered in this research include sudden changes in the slopes and curvatures of paths traced by relevant points on the mechanism as well as force-deflection characteristics. The design methodologies will be developed by exploiting the change of boundary conditions that result when a point on the mechanism contacts another point or the rigid surface and causes a sudden change in the kinematic and kinetostatic be havior of the mechanism. The topology and the shape of the mechanism as well as the rigid surface near the mechanism will be designed for desired non-smooth behavior. Large deformation-based nonlinear elastic analysis, design sensitivity analysis, and non-smooth optimization techniques will be utilized to achieve the goals of this project.The successful completion of this project will lead to general principles and systematic design methodology for achieving non-smooth motions with single-piece compliant mechanisms - a capability not possible today. One of the anticipated goals of this project is to design a 'compliant crank', which makes conversion of reciprocating translation input to continuous uni-directional full rotational output with a single elastic structure. It will have an impact on micro scale devices as well as macro scale products. On the theoretical side, the optimization techniques to be developed in this research will contribute to general area of non-smooth optimization. One of the educational contributions of this project will be to make contact analysis and non-smooth optimization codes available on the internet for general access by the students, practicing engineers, and researchers.