![]() Finite elements method (FEM) and experimental results correlate well with the predictions based on the comparatively simple and concise design equations. Depending on the contour, the error of the calculated results is in the range of less than 2 % to less than 16 % for the suggested parameter range compared with the analytical solution. Four flexure hinge contours are investigated, the semi-circular, the corner-filleted, the elliptical, and the recently introduced bi-quadratic polynomial contour. The novel equations are obtained on the basis of a non-linear analytical model for a moment and a transverse force loaded beam with a variable contour height. This paper presents general design equations for the calculation of the rotational stiffness, maximal angular elastic deflection and rotational precision of various notch flexure hinges in dependence of the geometric hinge parameters. Notch flexure hinges are often used as revolute joints in high-precise compliant mechanisms, but their contour-dependent deformation and motion behaviour is currently difficult to predict. Below is finite element analysis of a basic flexure design showing areas of high stress during stage phone: 608.298.0855 fax:. ![]() Mad City Labs uses finite element analysis in the design process to verify proper flexure performance. Flexures combined with preloaded piezoactuators also eliminate backlash common to mechanical stages. Contrast this to the "slip stick" motion of standard mechanical stages containing slides and bearings or other piezo/friction based devices (such as "inchworm" motors). This unique characteristic provides highly repeatable motion which is independent of direction. Since flexure guided stages do not have parts which move against each other, they exhibit a complete lack of friction. By pushing on the stage center, pure linear motion is achieved. The hinges are extremely stiff in every direction except the direction of motion. These hinges are shown schematically on the right of the figure. The EDM pattern shown results in four identical hinges at the corners of the stage. To determine the load capacity or the size of beam section, it must satisfy the allowable stresses in both flexure (bending) and shear. The hinges are formed by electrical discharge machining (EDM) and the stage and the frame are made from a single piece of metal. Complex-shaped flexible-hinge mechanisms are generated from basic elastic segments by means of a bottom-up compliance (flexibility) approach. ![]() Since the piezoactuator is protected inside the flexure guided stage, mounting is much simpler and operation is safer.Ī typical flexure guided stage is shown above. With proper preloading, a pulling force can be generated, making a flexure guided stage useful for both pushing and pulling. This effectively decouples the unwanted motions in the PZT actuator and produces a pure linear translation. Flexure guided stages, by proper design, restrict each axis of the stage to move in only one direction. Additionally, while piezoactuators are excellent at pushing, they are very poor at pulling.Īll of the above problems can be overcome through the use of flexure guided stages. When mounting a piezoactuator, care must be taken to avoid damaging stresses. Piezoactuators are fragile and cannot tolerate shear forces. During expansion they twist and corkscrew, giving rise to unwanted motions. Understanding Noise at the Nanometer Scaleīy themselves, piezoactuators are of limited use as nanopositioning devices. Long Range Motion with Nanometer Precision is the third article in a series intended to give you a glimpse of the 2005 AISC Specification for Structural Steel Buildings (AISC 360-05) and the 13th edi-tion of the Manual of Steel Construction. Home Products Applications Catalog Custom/OEM Technical Information News International Sales Repairs Contact All About Flexure The 2005 AISC Specification combines flexural provisions for all shapes into one chapter. Flexure-based mechanisms are composed of slender beam-like spring elements in their mechanical design they are close to being ideal motion bearings with.
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