Folding responses of origami-inspired structures connected by groove compliant joints

2021 ◽  
pp. 1-12
Author(s):  
Qian Zhang ◽  
Yuanyuan Li ◽  
Ahmad BH Kueh ◽  
Zelun Qian ◽  
Jianguo Cai
Keyword(s):  
Performance Indicators ◽  
Specific Interest ◽  
Comprehensive Understanding ◽  
Plate Structure ◽  
Compliant Joints ◽  
Stress Contour ◽  
Compliant Joint ◽  
Geometrical Variation ◽  
Elliptical Holes ◽  
As Stress

Abstract Folding responses of a set of notch-type compliant joint candidates are first numerically explored before the victorious one is implemented in actuating the deployment of Miura origami-inspired plate structure. The considered notch-type compliant joints are groove, elliptical holes, rectangular holes, and outside LET types. The exploration and examination of the kinematic and dynamic characteristics of these joints include performance indicators such as stress contour, load-deformation, moment-angle, and stiffness-angle relationships for different geometric parameters, with a specific interest in their hysteretic behaviors. Considering various performance features, the groove joints have been identified as the most suitable to be employed as the Miura origami-inspired hinge. The Miura origami-inspired plate folding behaviors are further explored considering various numbers and placements of groove joints. It has been found that the Miura plate performs better with the groove joint compared to that without one and that the single and double groove joint modes are inter-correlated. The study offers a comprehensive understanding of the effects of geometrical variation of numerous compliant joints on the folding behaviors as well as the further implementation of the victorious one in actuating the deployment of the Miura origami-inspired plate structure in accordance with the number and location of the joint.

Design of a Compact Actuated Compliant Elbow Joint

2014 ◽  
Vol 14 (08) ◽  
pp. 1440030 ◽  
Author(s):  
Johannes Gerard Kleinjan ◽  
Alje Geert Dunning ◽  
Justus Laurens Herder
Keyword(s):  
Smart Materials ◽  
Performance Indicators ◽  
Elbow Joint ◽  
Large Deflection ◽  
Rotational Axis ◽  
Half Cycle ◽  
Compliant Joints ◽  
Compliant Joint ◽  
Cycle Efficiency

Compactness is a valuable property in designs of assistive devices and exoskeletons. Current devices are large and stigmatizing in the eyes of the users. The cosmetic appearance will increase by reducing the size. The users want a device that is small enough to be worn underneath the clothes, so it becomes unnoticeable. The goals of this paper are (1) to provide an overview of the shape-changing-material-actuated large-deflection compliant rotational joints, (2) provide new introduced performance indicators that evaluate the designs on performance with respect to volume or weight and (3) design a compact active assistive elbow device as a case study. In order to reach these goals, two evolving fields of study are brought together that have great potential to reduce the size of exoskeletons: smart materials and compliant rotational joints. Smart materials have the ability to change their shape, which make them suitable as actuators. Compliant joints can be compact, since they are made out of one piece of material. An overview of shape-changing-material-actuated large-deflection compliant rotational joints is presented. Performance indicators are proposed to evaluate the existing designs and the prototype. As a case study a compact actuated rotational elbow joint is presented. An antagonistic actuator made from shape memory alloy wires is able to carry an external load and to actuate to move the arm to different positions. The compliant joint is optimized to balance the weight of the arm and to auto-align with the rotational axis of the human elbow joint. A prototype is able to generate a volume specific stall torque of 5.77 ⋅ 103 Nm/m3, produces a work density of 7.27 ⋅ 103 J/m3 based on volumes including isolation covers and the half-cycle efficiency of the device is 3.6%. The prototype is able to balance and actuate a torque of 1.1 Nm.

Design of a Contact-Aided Compliant Notched-Tube Joint for Surgical Manipulation in Confined Workspaces

2017 ◽  
Vol 10 (1) ◽  
Author(s):  
Kyle W. Eastwood ◽  
Peter Francis ◽  
Hamidreza Azimian ◽  
Arushri Swarup ◽  
Thomas Looi ◽  
...  
Keyword(s):  
Sensitivity Analysis ◽  
Compliant Mechanism ◽  
Surgical Instruments ◽  
Minimally Invasive Neurosurgery ◽  
Fem Simulations ◽  
Trade Off ◽  
Compliant Joints ◽  
Compliant Joint ◽  
Joint Mechanism ◽  
Surgical Manipulation

This work presents a novel miniature contact-aided compliant joint mechanism that can be integrated into millimeter-sized manual or robotic surgical instruments. The design aims to address the trade-off between notched-tube compliant joints' range of motion and stiffness, while also ensuring a compact form factor. The mechanism is constructed from a nitinol tube with asymmetric cutouts and is actuated in bending by a cable. The innovative feature of this design is the incorporation of a contact aid into the notched-tube topology, which acts to both increase the stiffness of the joint and change the shape that it undertakes during bending. Using finite element modeling (FEM) techniques, we present a sensitivity analysis investigating how the performance of this contact-aided compliant mechanism (CCM) is affected by its geometry, and derive a kinematics and statics model for the joint. The FEM simulations and the kinematic and static models are compared to experimental results. The design and modeling presented in this study can be used to develop new miniature dexterous instruments, with a particular emphasis on applications in minimally invasive neurosurgery.

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.

Compliant Joint Design Principles for High Compressive Load Situations

2004 ◽  
Vol 127 (4) ◽  
pp. 774-781 ◽  
Author(s):  
Alexandre E. Guérinot ◽  
Spencer P. Magleby ◽  
Larry L. Howell ◽  
Robert H. Todd
Keyword(s):  
Compliant Mechanisms ◽  
Compressive Load ◽  
High Load ◽  
Compliant Joints ◽  
High Compression ◽  
Kinematic Behavior ◽  
Compliant Joint ◽  
Compressive Loads ◽  
Buckling Failure ◽  
And Inversion

Buckling failure has been a major obstacle in designing compliant joints in high compression applications. This paper describes two principles, isolation and inversion, that can be successfully applied to many compliant joints to increase their ability to withstand high compressive loads by avoiding buckling-prone loading conditions. Isolation and inversion give rise to a new breed of compliant joints called high compression compliant mechanisms (HCCM). HCCMs have many of the inherent advantages of compliant mechanisms with the additional qualities of high load-bearing joints. This added robustness in compression can be achieved without adversely affecting the kinematic behavior of the joint.

Approximating Hinges With Multimaterial Compliant Joints

2021 ◽  
Author(s):  
Independence Talken ◽  
Zijuan Liang ◽  
Mark Plecnik
Keyword(s):  
Range Of Motion ◽  
Thermoplastic Polyurethane ◽  
Joint Stiffness ◽  
Torsional Stiffness ◽  
Revolute Joints ◽  
Compliant Joints ◽  
Trade Offs ◽  
Two Samples ◽  
Compliant Joint ◽  
The Cost

Abstract This paper investigates the use of multimaterial compliant joints produced through additive manufacturing in order to approximate a revolute joint. Compliant joints benefit from low friction and reduced wear, but at the cost of increased joint stiffness, reduced range of motion, and a reduced ability to resist loading. In addition, they might also provide a poor approximation of the revolute joints they intend to replace. In this paper, we experiment with three multimaterial compliant joint configurations. The first joint emphasizes accurate kinematics, the second joint aims to reduce axis-aligned stiffness, and the third joint compromises between the two. Samples were fabricated on a desktop 3D printer using PLA (polylactic acid) as the rigid material and TPU (thermoplastic polyurethane) for its flexibility. Samples were measured for tensile stiffness, torsional stiffness, range of motion, and approximation of a hinge motion. Our results indicate design trade offs where joints that measure most ideal for one property will be least ideal for another. The most novel design in this paper straddles this trade off. In the end, the suitability of each joint design is determined by the loading, accuracy, and range of motion requirements posed by a given application.

Design of Small-Scale Statically Balanced Compliant Joints

2011 ◽  
Author(s):  
Brian D. Jensen ◽  
Cesare H. Jenkins
Keyword(s):  
Viscous Friction ◽  
Small Scale ◽  
Dynamic Force ◽  
Compliant Joints ◽  
Stiffness Design ◽  
Rigid Body Model ◽  
Compliant Joint ◽  
Internal Forces ◽  
Low Stiffness ◽  
Torsion Bar

This paper demonstrates a low stiffness compliant joint design obtained by balancing the energy stored within individual components of the mechanism. As a step toward a fully-compliant zero-stiffness joint, this paper presents the design of a partially-compliant joint. A wireform torsion bar partially compliant joint was optimized using a pseudo rigid body model. A low stiffness design was obtained by balancing the energy stored within individual components of the mechanism. The joint was then fabricated using piano wire, polypropylene and Delrin®. During testing it was found that friction in the joint was greater than any internal forces allowing the joint to be neutrally stable in all positions. Dynamic force deflection data on the joints was collected in order to investigate the friction characteristics. The Delrin® joint exhibited only Coulomb friction while the polypropylene model exhibited both Coulomb and viscous friction.

Design and Optimization of a Contact-Aided Compliant Mechanism for Passive Bending

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Yashwanth Tummala ◽  
Aimy Wissa ◽  
Mary Frecker ◽  
James E. Hubbard
Keyword(s):  
Design Optimization ◽  
Compliant Mechanism ◽  
Leading Edge ◽  
Optimization Procedure ◽  
Peak Stress ◽  
Nonlinear Bending ◽  
Design And Optimization ◽  
Compliant Joints ◽  
Compliant Joint

A contact-aided compliant mechanism (CCM) called a compliant spine (CS) is presented in this paper. It is flexible when bending in one direction and stiff when bending in the opposite direction, giving it a nonlinear bending stiffness. The fundamental element of this mechanism is a compliant joint (CJ), which consists of a compliant hinge (CH) and contact surfaces. The design of the compliant joint and the number of compliant joints in a compliant spine determine its stiffness. This paper presents the design and optimization of such a compliant spine. A multi-objective optimization problem with three objectives is formulated in order to perform the design optimization of the compliant spine. The goal of the optimization is to minimize the peak stress and mass while maximizing the deflection, subject to geometric and other constraints. Flapping wing unmanned air vehicles, also known as ornithopters, are used as a case study in this paper to test the accuracy of the design optimization procedure and to prove the efficacy of the compliant spine design. The optimal compliant spine designs obtained from the optimization procedure are fabricated, integrated into the ornithopter's wing leading edge spar, and flight tested. Results from the flight tests prove the ability of the compliant spine to produce an asymmetry in the ornithopter's wing kinematics during the up and down strokes.

Performance indicators for student services

1990 ◽  
Vol 18 (1) ◽  
pp. 3-12 ◽  
Author(s):  
Sally Aldridge ◽  
David Legge
Keyword(s):  
Student Services ◽  
Performance Indicators

A Latent State-Trait Analysis of Current Achievement Motivation Across Different Tasks of Cognitive Ability

2017 ◽  
Vol 33 (5) ◽  
pp. 318-327
Author(s):  
Philipp Alexander Freund ◽  
Vanessa Katharina Jaensch ◽  
Franzis Preckel
Keyword(s):  
Cognitive Ability ◽  
Task Performance ◽  
Achievement Motivation ◽  
Fear Of Failure ◽  
Specific Task ◽  
Test Taker ◽  
Specific Interest ◽  
Probability Of Success ◽  
Ability Tests ◽  
Perceived Challenge

Abstract. The current study investigates the behavior of task-specific, current achievement motivation (CAM: interest in the task, probability of success, perceived challenge, and fear of failure) across a variety of reasoning tasks featuring verbal, numerical, and figural content. CAM is conceptualized as a state-like variable, and in order to assess the relative stability of the four CAM variables across different tasks, latent state trait analyses are conducted. The major findings indicate that the degree of challenge a test taker experiences and the fear of failing a given task appear to be relatively stable regardless of the specific task utilized, whereas interest and probability of success are more directly influenced by task-specific characteristics and demands. Furthermore, task performance is related to task-specific interest and probability of success. We discuss the implications and benefits of these results with regard to the use of cognitive ability tests in general. Importantly, taking motivational differences between test takers into account appears to offer valuable information which helps to explain differences in task performance.

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