Bionic design of a curvature-adjustable flexure hinge inspired by red blood cells

Abstract

Recent years have witnessed an ever-increasing research interest in experience-driven and topology-optimization design of flexure hinges for use in compliant mechanisms. In this paper, we report the bionic design of a new notch flexure hinge with adjustable curvatures inspired by the biconcave disk morphology of red blood cells. The biconcave shape maintains red blood cells excellent deformability and surface properties that motivates the bio-inspired design by learning from nature. By imitating the biconcave shape of red blood cells using the quartic Bézier curve, the contour of a cluster of bio-inspired flexure hinges in the presence of positive and negative curvatures can be parametrically adjusted. The closed-form equations of compliance, precision and the maximum stress of the bio-inspired flexure hinge are derived based on Castigliano's second theorem and Timoshenko beam theory. Comparative studies verify the well precision and low stress of such a new flexure hinge. At last, an amplified piezoelectric actuator is designed with the bio-inspired flexure hinge as an application case. Also interestingly, adjustable curvatures of the presented bio-inspired flexure hinge make the simultaneous shape and parameter optimization effective.