Two Stage Design of Compliant Mechanisms With Superelastic Compliant Joints

2017 ◽  
Author(s):  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Functionally Graded ◽  
Two Stage ◽  
Stage Design ◽  
Rigid Link ◽  
Starting Point ◽  
Single Piece ◽  
Two Stage Design

The design of compliant mechanisms made of Nickel Titanium (NiTi) Shape Memory Alloys (SMAs) is considered to exploit the superelastic behavior of the material to achieve tailored high flexibility on demand. This paper focuses on two-stage design optimization of compliant mechanisms, as a systematic method for design of the composition of the functionally graded NiTi material within the compliant mechanism devices. The location, as well as geometric and mechanical properties, of zones of high and low flexibility will be selected to maximize mechanical performance. The proposed two-stage optimization procedure combines the optimization of an analytical model of a single-piece functionally graded unit, with a detailed FEA of a continuous compliant mechanism. In the first stage, a rigid-link model is developed to initially approximate the behavior of the compliant mechanism. In the second stage the solution of the rigid-link problem serves as the starting point for a continuous analytical model where the mechanism consists of zones with different material properties and geometry, followed by a detailed FEA of a compliant mechanism with integrated zones of superelasticity. The two-stage optimization is a systematic approach for compliant mechanism design with functional grading of the material to exploit superelastic response in controlled manner. Direct energy deposition, as an additive manufacturing technology, is foreseen to fabricate assemblies with multiple single piece functional graded components. This method could be applied to bio-inspired structures, flapping wings, flexible adaptive structures and origami inspired compliant mechanisms.

A Two-Stage Design Method for Compliant Mechanisms Having Specified Non-Linear Output Paths

2006 ◽  
Author(s):  
Masakazu Kobayashi ◽  
Hiroshi Yamakawa ◽  
Shinji Nishiwaki ◽  
Kazuhiro Izui ◽  
Masataka Yoshimura
Keyword(s):  
Topology Optimization ◽  
Shape Optimization ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Design Method ◽  
Two Stage ◽  
Traditional Methods ◽  
Stage Design ◽  
Second Stage ◽  
Additional Constraints

Compliant mechanisms generated by traditional topology optimization methods have linear output response, and it is difficult for traditional methods to implement mechanisms having non-linear output responses, such as nonlinear deformation or path. To design a compliant mechanism having a specified nonlinear output path, a two-stage design method based on topology and shape optimization is constructed here. In the first stage, topology optimization generates an initial and conceptual compliant mechanism based on ordinary design conditions, with “additional” constraints that are used to control the output path at the second stage. In the second stage, an initial model for the shape optimization is created, based on the result of the topology optimization, and the additional constraints are replaced by spring elements. The shape optimization is then executed, to generate a detailed shape of the compliant mechanism having the desired output path. In this stage, parameters that represent the outer shape of the compliant mechanism and the properties of spring elements are used as design variables in the shape optimization. In addition to configuration of the specified output path, executing the shape optimization after the topology optimization also makes it possible to consider the stress concentration and large displacement effects. This is an advantage offered by the proposed method, since it is difficult for traditional methods to consider these aspects, due to inherent limitations of topology optimization.

Tubular electrostatic precipitators of two-stage design

1981 ◽  
Vol 6 (1-6) ◽  
pp. 239-244 ◽  
Author(s):  
Harish S. Surati ◽  
Michael R. Beltran ◽  
Isaac Raigorodsky
Keyword(s):  
Two Stage ◽  
Stage Design ◽  
Electrostatic Precipitators ◽  
Two Stage Design

Compliant Pantographs via the Pseudo-Rigid-Body Model

1998 ◽  
Author(s):  
Andrew J. Nielson ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Test Results ◽  
Rigid Link ◽  
Body Model ◽  
Design Flexibility ◽  
Model Predictions ◽  
Rigid Body Model ◽  
Classical Mechanism

Abstract This paper uses a familiar classical mechanism, the pantograph, to demonstrate the utility of the pseudo-rigid-body model in the design of compliant mechanisms to replace rigid-link mechanisms, and to illustrate the advantages and limitations of the resulting compliant mechanisms. To demonstrate the increase in design flexibility, three different compliant mechanism configurations were developed for a single corresponding rigid-link mechanism. The rigid-link pantograph consisted of six links and seven joints, while the corresponding compliant mechanisms had no more than two links and three joints (a reduction of at least four links and four joints). A fourth compliant pantograph, corresponding to a rhomboid pantograph, was also designed and tested. The test results showed that the pseudo-rigid-body model predictions were accurate over a large range, and the mechanisms had displacement characteristics of rigid-link mechanisms in that range. The limitations of the compliant mechanisms included reduced range compared to their rigid-link counterparts. Also, the force-deflection characteristics were predicted by the pseudo-rigid-body model, but they did not resemble those for a rigid-link pantograph because of the energy storage in the flexible segments.

A New Self-Adjusting CVT Configuration Using Compliant Mechanisms

2002 ◽  
Author(s):  
Myles T. Christensen ◽  
Spencer P. Magleby ◽  
Larry L. Howell ◽  
Robert H. Todd ◽  
Clint Mortensen
Keyword(s):  
Analytical Model ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Continuously Variable Transmission ◽  
Special Design ◽  
Design Considerations ◽  
Variable Transmission

This paper introduces a new configuration of a Continuously Variable Transmission (CVT) that is self-adjusting and designed as a compliant mechanism. This new configuration is called the Pivot-Arm CVT. The criteria for classification as a Pivot-Arm CVT is discussed. An analytical model describing the performance of the Pivot-Arm CVT is developed. Special design considerations which may be useful in implementing Pivot-Arm CVTs are introduced and explained. The Pivot-Arm CVT model is validated through controlled testing of two Pivot-Arm CVT prototypes.

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