Design of Contact-aided Compliant Mechanisms to Generate Sophisticated Motions

这项拨款为开发基于系统优化的设计方法提供资金，用于接触辅助柔顺机构。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，而且在性能上优于传统的刚体关节机构。在这个项目中，利用柔性机构弹性连续体的不同部分之间的间歇接触来获得非光滑运动。本研究要考虑的非光滑运动包括机构上相关点所跟踪的路径的斜率和曲率的突然变化以及力-挠度特性。设计方法将通过利用边界条件的变化来开发，当机构上的一个点与另一个点或刚性表面接触并导致机构的运动学和动静力学行为的突然变化时，会产生边界条件的变化。机构的拓扑和形状以及机构附近的刚性表面将被设计为期望的非光滑行为。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。该项目的成功完成将导致一般原理和系统的设计方法，以实现单件柔性机构的非光滑运动-这是目前不可能实现的能力。该项目的预期目标之一是设计一种“柔性曲柄”，该曲柄可以通过单一弹性结构将往复平移输入转换为连续的单向全旋转输出。它将对微观规模的设备以及宏观规模的产品产生影响。在理论方面，本研究开发的优化技术将为非光滑优化的一般领域做出贡献。这个项目的教育贡献之一是将接触分析和非光滑优化代码放到互联网上，供学生、实践工程师和研究人员访问。

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.