A Novel Sandwich Flexure Blade With Improved Out-of-Plane Stiffness

Abstract High out-of-plane stiffness is crucial in flexure-based motion stages that offer in-plane Degrees of Freedom (DoF). High out-of-plane stiffness helps support large payloads, suppress parasitic motions, and mitigate the adverse effects of out-of-plane vibration modes. Low in-plane stiffness is also essential because it increases the DoF range of motion and reduces the actuation effort. Increasing the out-of-plane stiffness and decreasing the in-plane stiffness simultaneously in flexure mechanisms is challenging because both these stiffness arise from the same flexible elements leading to an inherent tradeoff. This paper resolves this tradeoff by proposing a novel sandwich flexure blade architecture that improves the out-of-plane stiffness without affecting the in-plane stiffness. Closed-form analytical models are presented for the out-of-plane translational and rotational stiffness of the single-layer (or conventional) flexure blade and the novel sandwich flexure blade based on Timoshenko beam theory that closely match with Finite Element Analysis (FEA) results. Superior performance of the sandwich flexure blade over the conventional flexure blades is demonstrated and several design insights into the performance of the sandwich flexure blades are discussed based on the analytical stiffness models.