Systematic Synthesis of Large Displacement Contact-Aided Monolithic Compliant Mechanisms

Abstract

A single-piece contact-aided compliant mechanism (CCM) deforms to use one or many contact interactions to deliver the prescribed intricate input–output functionality. We present an automated synthesis procedure to design CCMs to trace large, non-smooth paths. Such paths can be traced by rigid-body or partially compliant mechanisms as well but the complexity, bulkiness and the presence of hinges is a disadvantage in terms of increased friction, backlash, need for lubrication, noise, and vibrations. In designing CCMs, both curved frame and two-dimensional finite elements are employed to represent the continuum and simulate the formation of contact sites. A contact site is one that allows relative rotation/sliding of a deforming member with respect to the neighboring one it is in contact with. The proposed design algorithm uses commercial software for large displacement contact analysis. The overall procedure automatically determines the CCM topology, feature shapes and sizes, and therefore the number (e.g., single or multiple) and nature (e.g., stiction or sliding) of contact sites. It systematically favors the continuum designs with lower function values when the synthesis problem is posed using a minimization objective. Synthesis of CCMs is exemplified for path generation applications though the proposed method can be employed for any generic kinematic task.