Design of Contact-aided Compliant Mechanisms to Generate Sophisticated Motions

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

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.