Book•
Flexures: Elements of Elastic Mechanisms
08 Aug 2000-
TL;DR: Flexure Design: Advantages and Disadvantages of Flexures as discussed by the authors The main advantages and disadvantages of flexible design are: Basic Elasticity. Fatigue. Vibrations and Natural Frequencies of Continuous Systems.
Abstract: Introduction: Advantages and Disadvantages of Flexures. Goals of Flexure Design. Essentials: Basic Elasticity. Behavior of Materials. Fatigue. Bending of Symmetric Beams. Rigid Body Dynamics: Linear Systems Theory. Vibrations and Natural Frequencies of Continuous Systems. Flexure Elements: Leaf Type Springs. Notch Hinge. Two Axis Hinges. The Four Bar Link. Flexure Systems: General Model for Dynamics of planar Flexures. Hinges of Rotational Symmetry: The Disc Coupling. Rotationally Symmetric Leaf Type Hinge. The Bellows as a Flexure Element. Levers. Manufacturing and Assembly Considerations: Machining and Heat Treatment of Some Common Flexure Materials.
Citations
More filters
TL;DR: A detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications, including both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.
Abstract: This review comprises a detailed survey of ongoing methodologies for soft actuators, highlighting approaches suitable for nanometer- to centimeter-scale robotic applications. Soft robots present a special design challenge in that their actuation and sensing mechanisms are often highly integrated with the robot body and overall functionality. When less than a centimeter, they belong to an even more special subcategory of robots or devices, in that they often lack on-board power, sensing, computation, and control. Soft, active materials are particularly well suited for this task, with a wide range of stimulants and a number of impressive examples, demonstrating large deformations, high motion complexities, and varied multifunctionality. Recent research includes both the development of new materials and composites, as well as novel implementations leveraging the unique properties of soft materials.
897 citations
TL;DR: In this article, the drawbacks of typical flexure connectors are investigated and cataloged, and several new designs for highly effective, kinematically-behaved compliant joints are proposed.
Abstract: Flexure joints are widely used to approximate the function of traditional mechanical joints, while offering the benefits of high precision, long life, and ease of manufacture. This paper investigates and catalogs the drawbacks of typical flexure connectors and presents several new designs for highly-effective, kinematically-behaved compliant joints. A revolute and a translational compliant joint are proposed (Figure 1), both of which offer great improvements over existing flexures in the qualities of (1) large range of motion, (2) minimal axis drift, (3) increased off-axis stiffness, and (4) reduced stress-concentrations. Analytic stiffness equations are developed for each joint and parametric computer models are used to verify their superior stiffness properties. A catalog of design charts based on the parametric models is also presented, allowing for rapid sizing of the joints for custom performance. Finally, two multi-degree-of-freedom joints are proposed as modifications to the revolute joint. These include a compliant universal joint and a compliant spherical joint, both designed to provide high degrees of compliance in the desired direction of motion and high stiffness in other directions.Copyright © 2002 by ASME
339 citations
TL;DR: The kinematic and dynamic modeling of the manipulator are conducted by resorting to compliance and stiffness analysis based on the matrix method, which are validated by finite-element analysis (FEA).
Abstract: In this paper, a concept of totally decoupling is proposed for the design of a flexure parallel micromanipulator with both input and output decoupling. Based on flexure hinges, the design procedure for an XY totally decoupled parallel stage (TDPS) is presented, which is featured with decoupled actuation and decoupled output motion as well. By employing (double) compound parallelogram flexures and a compact displacement amplifier, a class of novel XY TDPS with simple and symmetric structures are enumerated, and one example is chosen for further analysis. The kinematic and dynamic modeling of the manipulator are conducted by resorting to compliance and stiffness analysis based on the matrix method, which are validated by finite-element analysis (FEA). In view of predefined performance constraints, the dimension optimization is carried out by means of particle swarm optimization, and a prototype of the optimized stage is fabricated for performance tests. Both FEA and experimental studies well validate the decoupling property of the XY stage that is expected to be adopted into micro-/nanoscale manipulations.
336 citations
TL;DR: In this paper, a general analytical framework is developed that enables a designer to parametrically predict the performance characteristics such as mobility, overconstraint, stiffness variation, and error motions, of beam-based flexure mechanisms without resorting to tedious numerical or computational methods.
Abstract: The beam flexure is an important constraint element in flexure mechanism design. Nonlinearities arising from the force equilibrium conditions in a beam significantly affect its properties as a constraint element. Consequently, beam-based flexure mechanisms suffer from performance tradeoffs in terms of motion range, accuracy and stiffness, while benefiting from elastic averaging. This paper presents simple yet accurate approximations that capture the effects of load-stiffening and elastokinematic nonlinearities in beams. A general analytical framework is developed that enables a designer to parametrically predict the performance characteristics such as mobility, over-constraint, stiffness variation, and error motions, of beam-based flexure mechanisms without resorting to tedious numerical or computational methods. To illustrate their effectiveness, these approximations and analysis approach are used in deriving the force-displacement relationships of several important beam-based flexure constraint modules, and the results are validated using finite element analysis. Effects of variations in shape and geometry are also analytically quantified.
319 citations
Cites background or result from "Flexures: Elements of Elastic Mecha..."
...Introduction and Background From the perspective of precision machine design [1-4], flexures are essentially constraint elements that utilize material elasticity to allow small yet frictionless motions....
[...]
...Linear analysis of the parallelogram flexure module, along with the kinematic requirement of constant beam arc-length, yields the following standard results [3]....
[...]
...Solving Euler’s equation for the simple beam yields the following well-known results [3, 10], where the normalized tensile axial force 2 k p ....
[...]
01 Apr 2010-Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology
TL;DR: In this paper, the authors demonstrate how to use freedom and constraint topology (FACT) to synthesize concepts for the multi-degree of freedom, parallel precision flexure systems that fall within the scope of Part I.
Abstract: In Part II of this paper we demonstrate how to use freedom and constraint topology (FACT) to synthesize concepts for the multi-degree of freedom, parallel precision flexure systems that fall within the scope of Part I. Several examples are provided to demonstrate how the Principle of Complementary Topologies and geometric entities from Part I are (i) relevant to flexure system characteristics, (ii) used to visualize the possible layout of flexure constraints to achieve a desired motion and (iii) used to select redundant constraints. A synthesis process is presented, and then used to visualize and construct a flexure system concept with the requisite kinematic characteristics and redundant constraints that provide increased stiffness, load capacity, and symmetry. The output of the process is a flexure concept that would then be modeled and refined by existing modeling and analysis methods.
220 citations