Towards Statically Balanced Compliant Joints Using Multimaterial 3D Printing

2014 ◽  
Author(s):  
Arnaud Bruyas ◽  
François Geiskopf ◽  
Pierre Renaud
Keyword(s):  
3D Printing ◽  
Range Of Motion ◽  
Elastic Material ◽  
Geometry Optimization ◽  
Compliant Joints ◽  
Stiffness Properties ◽  
Large Joint ◽  
Hyper Elastic ◽  
Bistable Mechanism ◽  
Novel Design

Compliant joints are widely used in mechanisms when accurate movements are required. With no assembly requested, they are also a great tool for mesoscale robotics, a field in which compactness and large joint amplitudes are necessary features. In this paper, an original multi-material compliant revolute joint is presented. Taking advantage of multi-material 3D printing, it exhibits a novel design with the integration of an hyper-elastic material. Thanks to a helical shape design, a large range of motion is obtained, and the incompressibility of the hyper-elastic material is used to improve the stiffness properties of the joint while keeping it compact. The spring effect of compliant joints makes mechanism actuation more difficult. The proposed joint is therefore designed with an integrated static balancing system in order to minimize actuation torques. The balancing system is composed of a bistable mechanism, which geometry optimization is presented. Experimental assessment demonstrate that the joint possesses a range of motion of 120°, and the balancing system reduces actuation moments by almost 60%.

Shape-Morphing Using Bistable Triangles With Dwell-Enhanced Stability

2018 ◽  
Author(s):  
Rami Alfattani ◽  
Craig Lusk
Keyword(s):  
Compliant Mechanism ◽  
Isosceles Triangle ◽  
Vertex Angle ◽  
The Novel ◽  
Shape Morphing ◽  
Compliant Joints ◽  
Cube Corner ◽  
The Stability ◽  
Bistable Mechanism ◽  
Novel Design

This paper presents a new design concept for a morphing triangle-shaped compliant mechanism. The novel design is a bistable mechanism that has one changeable side. These morphing triangles may be arrayed to create shapemorphing structures. The mechanism was based on a six-bar dwell mechanism that can fit in a triangle shape and has stable positions at the motion-limit (dead-center) positions. An example of the triangle-shaped compliant mechanism was designed and prototyped: an isosceles triangle with a vertex that changes from 120 degrees to 90 degrees and vice versa. Three of these in the 120-degree configuration lie flat and when actuated to the 90-degree configuration become a cube corner. This design may be of use for folding and packaging assistance. The force analysis and the potential energy analysis were completed to verify the stability of the triangle-shaped compliant mechanism. Because of its dead-center motion limits the vertex angle cannot be extended past the range of 90 degrees to 120 degrees in spite of the mechanism’s compliant joints. Furthermore, because it is a dwell mechanism, the vertex angle is almost immobile near its stable configurations, although other links in the mechanism move. This makes the stable positions of the vertex angle robust against stress relaxation and manufacturing errors. We believe this is the first demonstration of this kind of robustness in bistable mechanisms.

Design of Large-Displacement Compliant Joints

2004 ◽  
Vol 127 (4) ◽  
pp. 788-798 ◽  
Author(s):  
Brian P. Trease ◽  
Yong-Mo Moon ◽  
Sridhar Kota
Keyword(s):  
Range Of Motion ◽  
Parametric Models ◽  
Stress Concentrations ◽  
Concentration Effects ◽  
Element Analysis ◽  
Compliant Joints ◽  
Joint Range Of Motion ◽  
Stiffness Properties ◽  
Compliant Joint ◽  
Joint Range

This paper investigates the drawbacks of typical flexure connectors and presents several new designs for highly effective, kinematically well-behaved compliant joints. A revolute and a translational compliant joint are proposed, both of which offer great improvements over existing flexures in the qualities of (1) a large range of motion, (2) minimal “axis drift,” (3) increased off-axis stiffness, and (4) a 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. A joint range of motion has been calculated with finite element analysis, including stress concentration effects.

scholarly journals Shape-Morphing Using Bistable Triangles With Dwell-Enhanced Stability

2020 ◽  
Vol 12 (5) ◽  
Author(s):  
Rami Alfattani ◽  
Craig Lusk
Keyword(s):  
Compliant Mechanism ◽  
Isosceles Triangle ◽  
Vertex Angle ◽  
The Novel ◽  
Shape Morphing ◽  
Compliant Joints ◽  
Cube Corner ◽  
Manufacturing Errors ◽  
Bistable Mechanism ◽  
Novel Design

Abstract This paper presents a new design concept for a morphing triangle-shaped compliant mechanism. The novel design is a bistable mechanism that has one changeable side. These morphing triangles may be arrayed to create shape-morphing structures. The mechanism design was based on a six-bar dwell mechanism that can fit in a triangle shape and has stable positions at the motion-limit (dead-center) positions. An example of the triangle-shaped compliant mechanism was designed and prototyped: an isosceles triangle with a vertex that changes from 120 deg to 90 deg and vice versa. Three of these in the 120-deg configuration lie flat and when actuated to the 90-deg configuration become a cube corner. This design may be of use for folding and packaging assistance. The mechanism was designed using geometric constraint programming. Force and potential energy analyses characterize the triangle mechanism’s stability. Because of its dead-center motion limits, the vertex angle of the triangle cannot be extended past the range of 90–120 deg, in spite of the mechanism’s compliant joints. Furthermore, because it is a dwell mechanism, the vertex angle is almost immobile near its stable configurations, although other links in the mechanism move. This makes the stable positions of the vertex angle robust against stress relaxation and manufacturing errors. We believe this is the first demonstration of this kind of robustness in bistable mechanisms.

scholarly journals A millifluidic chip for cultivation of fish embryos and toxicity testing fabricated by 3D printing technology

RSC Advances ◽  
2021 ◽  
Vol 11 (33) ◽  
pp. 20507-20518
Author(s):  
Petr Panuška ◽  
Zuzana Nejedlá ◽  
Jiří Smejkal ◽  
Petr Aubrecht ◽  
Michaela Liegertová ◽  
...  
Keyword(s):  
3D Printing ◽  
Toxicity Testing ◽  
Toxicity Screening ◽  
Printing Technology ◽  
3D Printing Technology ◽  
Fish Embryos ◽  
3D Printed ◽  
Novel Design

A novel design of 3D printed zebrafish millifluidic system for embryonic long-term cultivation and toxicity screening has been developed. The chip unit provides 24 cultivation chambers and a selective individual embryo removal functionality.

scholarly journals Design of Compliant Joints for Large Scale Structures

2020 ◽  
Author(s):  
Angela Nastevska ◽  
Jovana Jovanova ◽  
Mary Frecker
Keyword(s):  
Large Scale ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Small Scale ◽  
Nonlinear Bending ◽  
Large Scale Structures ◽  
Compliant Joints ◽  
Scale Structures ◽  
High Level ◽  
Novel Design

Abstract Large scale structures can benefit from the design of compliant joints that can provide flexibility and adaptability. A high level of deformation is achieved locally with the design of flexures in compliant mechanisms. Additionally, by introducing contact-aided compliant mechanisms, nonlinear bending stiffness is achieved to make the joints flexible in one direction and stiff in the opposite one. All these concepts have been explored in small scale engineering design, but they have not been applied to large scale structures. In this paper the design of a large scale compliant mechanism is proposed for novel design of a foldable shipping container. The superelasticity of nickel titanium is shown to be beneficial in designing the joints of the compliant mechanism.

scholarly journals Comparison of Ortho-planar Spring design optimization based on Linear Elastic and Hyper Elastic Materials

2018 ◽  
Vol 166 ◽  
pp. 01004
Author(s):  
Ruetai Graipaspong ◽  
Teeranoot Chanthasopeephan
Keyword(s):  
Topology Optimization ◽  
Elastic Material ◽  
Maximum Stress ◽  
Nonlinear Material ◽  
Small Displacement ◽  
Linear Elastic Material ◽  
Output Displacement ◽  
Linear Elastic ◽  
Hyper Elastic ◽  
Matlab Programming

In this paper, compliant Ortho-planar spring was designed based on a three-dimensional topology optimization method. The computation was developed using MATLAB programming. The objective of this work was to apply dual method to design an Ortho-planar spring while the design should have minimum mass and at the same time satisfy a set of constrained displacement. Throughout this paper, we analyzed a method for designing an Ortho-planar spring using linear elastic material and hyperelastic material. The results showed that under small displacement conditions, the output displacement, maximum stress magnitude, and the maximum stress of linear elastic assumption and hyper-elastic material were relatively close to each other. However, the mass fraction and the layout as the result of the optimization process was different. As for larger displacement, the maximum stress of linear elastic material appeared 2.59 times higher than the maximum stress of the hyper-elastic material model. The topology optimization output based on linear material was invalid because the topology of the computed Ortho-planar spring was not appeared as a one-piece layout while the design based on nonlinear material looked promising.

Development of Pressure-Driven Flow Rate Control Valve with Hyper-Elastic Material

2020 ◽  
Vol 29 (3) ◽  
pp. 251-258
Author(s):  
Kibum Lee ◽  
Jaeyong Cho ◽  
Inseon Lee ◽  
Jeongseop Ahn ◽  
Choonsoo Jang ◽  
...  
Keyword(s):  
Flow Rate ◽  
Elastic Material ◽  
Rate Control ◽  
Control Valve ◽  
Hyper Elastic ◽  
Flow Rate Control ◽  
Pressure Driven Flow ◽  
Pressure Driven

A Study on Dynamic Characteristics of Hyper-Elastic Shock Programmer with Truncated Conical Shape

2013 ◽  
Vol 871 ◽  
pp. 240-246
Author(s):  
Tae Ho Yang ◽  
Young Shin Lee ◽  
Yoon Jae Kim ◽  
Tae Hyeong Kim ◽  
Chang Won Shul ◽  
...  
Keyword(s):  
Elastic Material ◽  
Impact Test ◽  
Time History ◽  
Material Model ◽  
Wave Shape ◽  
Time Duration ◽  
Conical Shape ◽  
Design Variables ◽  
Hyper Elastic ◽  
The Impact

Polyurethane (PU) S80A was used as the material of the elastomer of the shock programmer in this paper. To validate Ogden hyper-elastic material model in simulation, the small impact test was performed. As the comparison for the time history of the acceleration between the impact test and simulation was performed. Using the cylindrical shock programmer, the constant used in Ogden hyper-elastic material model was calculated. The wave shape of the acceleration was obtained with the noised sign. To clearly obtain the wave shape of the acceleration the cylindrical shock programmer, the truncated conical shock programmer was used. Using the Ogden hyper-elastic material model, design variables of the shock programmer with the truncated conical shape was studied. Using the shock programmer with truncated conical shape the range on the level and time duration of the acceleration in simulation was from 494.9 m/s2 to 10941 m/s2 and from 1.3 msec to 23.5 msec, respectively.

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