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.

Design and Optimization of a Bend-and-Sweep Compliant Mechanism

2013 ◽  
Author(s):  
Yashwanth Tummala ◽  
Mary Frecker ◽  
Aimy Wissa ◽  
James E. Hubbard
Keyword(s):  
Optimization Problem ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Leading Edge ◽  
Von Mises Stress ◽  
Nsga Ii ◽  
Design And Optimization ◽  
Compliant Joint ◽  
Von Mises ◽  
Wing Morphing

A novel contact aided compliant mechanism called a bend-and-sweep compliant mechanism is presented. This mechanism has tailorable nonlinear stiffness properties in two orthogonal directions. The fundamental element of this compliant mechanism is the Angled Compliant Joint (ACJ), and the geometric parameters determine the stiffness. This paper presents the design and optimization of such a compliant mechanism. A multi-objective optimization problem was formulated for design optimization of the bend-and-sweep compliant mechanism. The objectives of the optimization problem were to maximize the bending and sweep displacements while minimizing the von Mises stress and mass of each mechanism. This optimization problem was solved using NSGA-II (a genetic algorithm). The results of this optimization for a single ACJ during upstroke and downstroke are presented. Results of two different loading conditions used during optimization of a single ACJ for upstroke are presented. Finally, optimization results comparing the performance of compliant mechanisms with one and two ACJs are also presented. It can be inferred from these results that the number of ACJs and the design of each ACJ determines the stiffness of the bend-and-sweep compliant mechanism. These mechanisms can be used in various applications. Ornithopters or flapping wing unmanned aerial vehicles have unique potential to revolutionize both civil and military applications. The overall goal of this research is to improve the performance of such ornithopters by passively morphing their wings. Passive wing morphing of ornithopters can be achieved by inserting contact-aided compliant mechanisms in the leading edge wing spar. Previously the authors have shown that bending of ornithopter wings can be achieved by integrating a one degree of freedom contact aided compliant mechanism called a compliant spine. The spine was inserted into the leading edge spar and successful flight testing has shown that passive wing bending in ornithopters is feasible and results in significant improvements in lift and thrust. In order to achieve a bio-inspired wing gait called continuous vortex gait, the wings of the ornithopter need to bend, sweep, and twist simultaneously. This can be achieved by using the bend-and-sweep compliant presented in this paper.

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.

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.

The role of computer aided engineering in the design optimization of exhaust after-treatment systems

1998 ◽  
Vol 212 (3) ◽  
pp. 169-186 ◽  
Author(s):  
P. A. Konstantinidis ◽  
G. C. Koltsakis ◽  
A. M. Stamatelos
Keyword(s):  
Design Optimization ◽  
Catalytic Converter ◽  
Exhaust System ◽  
Optimization Procedure ◽  
Computer Code ◽  
Computer Aided Engineering ◽  
Design And Optimization ◽  
Computer Aided ◽  
Context Specific ◽  
Exhaust After Treatment

The goals of employing computer aided engineering (CAE) tools have always been the improvement of product quality and the simultaneous reduction of the related time-to-market and development costs. The latter may be achieved when the optimization procedure is carried out without the need to construct and test numerous prototypes. CAE tools and methodologies, apart from the design phase, can also be employed for dedicated prediction and analysis purposes, with the intention to fully exploit the capabilities of the catalytic exhaust system. A set of fundamental CAE tools and the accompanying (CAE) methodology, aiming to assist the design optimization of catalytic exhaust systems for spark-ignition-engined vehicles, are presented. The set comprises the following individual cooperating modules: a transient exhaust system heat transfer code, a transient three-way catalytic converter (3W-CC) computer code with an accompanying kinetics tuning procedure, a 3W-CC database and an ageing assessment methodology. The CAE methodology may be exploited in the directions of exhaust system design and optimization, addressing the catalytic exhaust system as an entity that consists of interrelated components. In that context, specific examples of real practice are demonstrated. This methodology is already being extensively used by the authors in research and development of automotive exhaust after-treatment systems, with promising results.

Control Design for the Active Stabilization of Rail Wheelsets

2007 ◽  
Vol 130 (1) ◽  
Author(s):  
T. X. Mei ◽  
H. Li
Keyword(s):  
Design Method ◽  
Control Design ◽  
Optimization Procedure ◽  
Control Analysis ◽  
Design And Optimization ◽  
Stabilization Control ◽  
Number Of Factors ◽  
Parameter Variations ◽  
Active Stabilization

Through a detailed control assessment of a conventional railway wheelset, this paper addresses some of the key design issues in the development of active primary suspensions for the stabilization control of railway vehicles. It reveals the basic feedback requirements for achieving adequate stability and hence provides a useful insight of how active controllers may be structured. For the control design, a number of factors in addition to the stabilization are considered including the actuation requirements, creep forces at the wheel-rail contact, track following as well as robustness against parameter variations. Based on the outcome of the control analysis, the study proposes a design and optimization procedure for the development of active wheelset control. The design method is applied to a two-axle vehicle in a case study, which shows that the new design approach is advantageous when compared with other design methods previously studied.

A Collaborative Approach for Multidisciplinary Systems Reliability Design and Optimization

2013 ◽  
Vol 694-697 ◽  
pp. 911-914 ◽  
Author(s):  
Jun Zhang ◽  
Bing Zhang
Keyword(s):  
Design Optimization ◽  
Multidisciplinary Design Optimization ◽  
Optimization Procedure ◽  
Performance Measure ◽  
Multidisciplinary Design ◽  
Sequential Optimization ◽  
Optimization Strategy ◽  
Reliability Design ◽  
Design And Optimization ◽  
Subspace Optimization

In order to improve the efficiency and robustness of reliability-based multidisciplinary design optimization (RBMDO), a new collaborative strategy (named C-RBMDO) which integrates performance measure approach (PMA) and concurrent subspace optimization strategy (CSSO) is proposed. Both the mathematical model and optimization procedure are put forward. The traditional triple-level nested flowchart of RBMDO is decoupled with the sequential optimization and reliability assessment (SORA). The deterministic multidisciplinary design optimization and the multidisciplinary reliability analysis are executed by CSSO and PMA respectively. Finally, the proposed method is verified through the design example of gear transmission.

On stability optimization of the deployable bistable compliant structures mounted in the morphing skin: Method and implementation

2014 ◽  
Vol 229 (5) ◽  
pp. 943-956 ◽  
Author(s):  
Jianing Wu ◽  
Shaoze Yan ◽  
Yongxia Gu
Keyword(s):  
Genetic Algorithm ◽  
Optimization Problem ◽  
Compliant Mechanism ◽  
Research Effort ◽  
Optimal Performance ◽  
Optimal Parameters ◽  
Immune Genetic Algorithm ◽  
Design And Optimization ◽  
Optimal Stiffness

Morphing skin is the surface of the deployable frame which could reconfigure its shape to present optimal performance in all stages of a task for the re-entry aerospace vehicle. After many years of research effort, design concept and manufacturing methodologies of morphing skin have been developed, especially in the adoption of bistable compliant mechanism (BCM). In order to make morphing skins more stable to accommodate to the air flow and change its profile more accurately, one method on the design and optimization of stability characteristics for deployable BCMs of morphing skin is proposed in this paper. The optimization is developed by the aeroelastic formulation of the deployable BCM mounted on the morphing skin. The optimization problem is considered as a multi-objective-constraint issue and the parametric equations to get the optimal parameters are solved by the immune genetic algorithm. Besides, a case study is proposed to provide evidence that the method can come to the optimal stiffness of BCM, with which the effectiveness about the new method of design and optimization can be testified.

Experimental Validation of Compliant Joints in a Dynamic Spar Numerical Model

2016 ◽  
Author(s):  
Joseph Calogero ◽  
Mary Frecker ◽  
Zohaib Hasnain ◽  
James E. Hubbard
Keyword(s):  
Numerical Model ◽  
Compliant Mechanism ◽  
Shape Change ◽  
Moving Average ◽  
Leading Edge ◽  
Compliant Joints ◽  
Angle Function ◽  
Deflection Amplitude ◽  
Stiffness And Damping ◽  
Spatial Locations

A dynamic spar numerical model for passive shape change is validated for a single degree of freedom contact-aided compliant mechanism (CCM) in a flapping spar. CCMs are modeled as compliant joints: spherical joints with distributed mass and three axis nonlinear torsional spring-dampers. Several assumptions were made in the original formulation of the model, such as assuming the spars were rigid and a simple damping model for the compliant joints. An experiment was performed to validate the assumptions and tune the model. Four configurations of the leading edge spar were tested: a solid spar, a previously designed CCM at two spatial locations, and a modified version of the CCM. Reflective markers were placed on each configuration, then the spars were inserted into the wing roots of a clamped ornithopter. An array of computer vision cameras was used to track the spar and CCM kinematics as they were flapped. First, a flapping angle function was extracted using a moving average of the flapping cycles. Then, a genetic algorithm was implemented to tune the stiffness and damping parameters for each of the configuration, minimizing the root mean square error between the model and experimental marker kinematics. The model was able to capture the deflection amplitude and harmonics of the CCMs with very good agreement and minimal to no phase shift.

scholarly journals Hybrid Seven-bar Press Mechanism

2018 ◽  
Vol 12 (3) ◽  
pp. 181-187
Author(s):  
M. Erkan Kütük ◽  
L. Canan Dülger
Keyword(s):  
Genetic Algorithm ◽  
Objective Function ◽  
Design Optimization ◽  
Hybrid System ◽  
Degrees Of Freedom ◽  
Dimensional Synthesis ◽  
Design Variables ◽  
Optimization Study ◽  
Metal Stamping

An optimization study with kinetostatic analysis is performed on hybrid seven-bar press mechanism. This study is based on previous studies performed on planar hybrid seven-bar linkage. Dimensional synthesis is performed, and optimum link lengths for the mechanism are found. Optimization study is performed by using genetic algorithm (GA). Genetic Algorithm Toolbox is used with Optimization Toolbox in MATLAB®. The design variables and the constraints are used during design optimization. The objective function is determined and eight precision points are used. A seven-bar linkage system with two degrees of freedom is chosen as an example. Metal stamping operation with a dwell is taken as the case study. Having completed optimization, the kinetostatic analysis is performed. All forces on the links and the crank torques are calculated on the hybrid system with the optimized link lengths

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