The Scope for a Compliant Homokinetic Coupling Based on Review of Compliant Joints and Rigid-Body Constant Velocity Universal Joints

2012 ◽  
Author(s):  
Davood Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Constant Velocity ◽  
Compliant Mechanism ◽  
Analytical Data ◽  
Graph Representation ◽  
Universal Joint ◽  
Compliant Joints ◽  
Cylindrical Joint ◽  
Body Joints ◽  
Universal Joints

Many applications require a compliant mechanism to transmit rotation from one direct to another direct with constant velocity. This paper presents a literature survey towards the design of compliant constant velocity universal joints. The traditional constant velocity universal joints available from the literature were studied, classified and their mechanical efficiencies were compared. Also the graph representation of them was studied. In the same manner, literature review for different kind of compliant joints suitable for the Rigid-Body-Replacement of constant velocity universal joints was also performed. For the first time a comparison with analytical data of compliant joints was performed. All of compliant universal joints are non-constant velocity and designed based on rigid Hooke’s universal joint. Also we show there are no equivalent compliant joints for some rigid-body joints such as cylindrical joint, planar joint, spherical fork joint and spherical parallelogram quadrilateral joint. However, we may achieve them by combining numbers of available compliant joints. The universal joints found are non-compliant non-constant velocity universal joint, non-compliant constant velocity universal joint or compliant non-constant velocity universal joint. A compliant constant velocity universal joint has a great horizon for developments, for instance in medical or rehabilitation devices.

A Review on Compliant Joints and Rigid-Body Constant Velocity Universal Joints Toward the Design of Compliant Homokinetic Couplings

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
D. Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Constant Velocity ◽  
Compliant Mechanisms ◽  
Material Selection ◽  
Analytical Data ◽  
Graph Representations ◽  
Common Basis ◽  
Compliant Joints ◽  
Body Joints ◽  
Universal Joints

This paper presents for the first time a literature survey toward the design of compliant homokinetic couplings. The rigid-linkage-based constant velocity universal joints (CV joints) available from literature were studied, classified, their graph representations were presented, and their mechanical efficiencies compared. Similarly, literature is reviewed for different kinds of compliant joints suitable to replace instead of rigid-body joints in rigid-body CV joints. The compliant joints are compared based on analytical data. To provide a common basis for comparison, consistent flexure scales and material selection are used. It was found that existing compliant universal joints are nonconstant in velocity and designed based on rigid-body Hooke's universal joint. It was also discovered that no compliant equivalent exists for cylindrical, planar, spherical fork, and spherical parallelogram quadrilateral joints. We have demonstrated these compliant joints can be designed by combining existing compliant joints. The universal joints found in this survey are rigid-body non-CV joints, rigid-body CV joints, or compliant non-CV joints. A compliant homokinetic coupling is expected to combine the advantages of compliant mechanisms and constant velocity couplings for many applications where maintenance or cleanliness is important, for instance in medical devices and precision instruments.

Evaluation of Equivalent Spring Stiffness for Use in a Pseudo-Rigid-Body Model of Large-Deflection Compliant Mechanisms

1994 ◽  
Author(s):  
Larry L. Howell ◽  
Ashok Midha
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Spring Stiffness ◽  
Model Concept ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Body Joints

Abstract Compliant mechanisms gain some or all of their mobility from the flexibility of their members rather than from rigid-body joints only. More efficient and usable analysis and design techniques are needed before the advantages of compliant mechanisms can be fully utilized. In an earlier work, a pseudo-rigid-body model concept, corresponding to an end-loaded geometrically nonlinear, large-deflection beam, was developed to help fulfill this need. In this paper, the pseudo-rigid-body equivalent spring stiffness is investigated and new modeling equations are proposed. The result is a simplified method of modeling the force/deflection relationships of large-deflection members in compliant mechanisms. Flexible segments which maintain a constant end angle are discussed, and an example mechanism is analyzed. The resulting models are valuable in the visualization of the motion of large-deflection systems, as well as the quick and efficient evaluation and optimization of compliant mechanism designs.

A Fully Compliant Constant Velocity Universal Joint

2015 ◽  
Author(s):  
D. Farhadi Machekposhti ◽  
N. Tolou ◽  
J. L. Herder
Keyword(s):  
Rigid Body ◽  
Rotational Motion ◽  
Constant Velocity ◽  
Large Deflection ◽  
Experimental Results ◽  
Universal Joint ◽  
Compliant Structure ◽  
Body Model ◽  
Rigid Body Model ◽  
Kinematic Properties

This paper presents the concept and fabrication of a large deflection compliant Constant Velocity universal joint (CV joint). A novel compliant structure is proposed based on the 6R Hybrid spatial overconstrained linkage. Due to symmetry, its kinematic properties are such that can transfer rotational motion between two angled shafts with true constant velocity. The kinematic of the mechanism and the Pseudo-Rigid-Body model of its compliant configuration are studied and analyzed. A prototype was manufactured and experimentally evaluated. It was verified that the experimental results are consistent with the theoretical expectations.

Evaluation of Equivalent Spring Stiffness for Use in a Pseudo-Rigid-Body Model of Large-Deflection Compliant Mechanisms

1996 ◽  
Vol 118 (1) ◽  
pp. 126-131 ◽  
Author(s):  
L. L. Howell ◽  
A. Midha ◽  
T. W. Norton
Keyword(s):  
Rigid Body ◽  
Large Deflection ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Spring Stiffness ◽  
Model Concept ◽  
Analysis And Design ◽  
Body Model ◽  
Rigid Body Model ◽  
Body Joints

Compliant mechanisms gain some or all of their mobility from the flexibility of their members rather than from rigid-body joints only. More efficient and usable analysis and design techniques are needed before the advantages of compliant mechanisms can be fully utilized. In an earlier work, a pseudo-rigid-body model concept, corresponding to an end-loaded geometrically nonlinear, large-deflection beam, was developed to help fulfill this need. In this paper, the pseudo-rigid-body equivalent spring stiffness is investigated and new modeling equations are proposed. The result is a simplified method of modeling the force/deflection relationships of large-deflection members in compliant mechanisms. The resulting models are valuable in the visualization of the motion of large-deflection systems, as well as the quick and efficient evaluation and optimization of compliant mechanism designs.

On the Nomenclature and Classification of Compliant Mechanisms: Abstractions of Mechanisms and Mechanism Synthesis Problems

1992 ◽  
Author(s):  
Ashok Midha ◽  
Tony W. Norton ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Mechanism Synthesis ◽  
Levels Of Abstraction ◽  
Significant Growth ◽  
Important Field ◽  
The Common ◽  
Body Joints

Abstract A compliant mechanism is one which gains all or part of its mobility from the relative flexibility of its members rather than from rigid-body joints only. Compliant mechanisms offer clear advantages, such as need for fewer parts, less wear, noise and backlash due to clearances, when compared to rigid-body mechanisms performing similar functions. This important field is expected to undergo significant growth as materials with superior properties are developed. In the development of compliant mechanisms, the establishment of nomenclature and classification is of primary importance. This paper discusses common representations, i.e. names and diagrams, for a compliant mechanism. Names and diagrams will be shown to be similar because they represent “abstractions” of the same mechanism. The concept of “levels of abstraction” is introduced, and common levels of abstraction are identified. The relevance of this concept to the naming of mechanisms is shown by applying it to both rigid-body and compliant mechanism examples. Nomenclature is proposed for several of the common levels of abstraction, and issues involved in naming mechanisms are discussed. Finally, a discussion of synthesis types is presented, as are the advantages, disadvantages, and issues involved in the synthesis of a compliant mechanism.

scholarly journals Optimization-Based Design of a Fully-Compliant Bistable Micromechanism

2000 ◽  
Author(s):  
Matthew B. Parkinson ◽  
Brian D. Jensen ◽  
Gregory M. Roach
Keyword(s):  
Power Consumption ◽  
Rigid Body ◽  
Compliant Mechanism ◽  
Optimization Techniques ◽  
Reduce Power Consumption ◽  
Actuation Mechanism ◽  
Bistable Mechanism ◽  
Body Joints ◽  
Optimization Based Design

Abstract Micro-bistable mechanisms are used in microswitches and microvalves to reduce power consumption as power is applied only to switch states. Many of the bistable mechanism designs that have been presented incorporate rigid-body joints. These joints introduce unwanted friction and poor repeatability into the mechanism motion. A fully-compliant mechanism avoids these problems. Optimization techniques were used to find fully-compliant bistable micromechanism designs. The chosen objective was to minimize the displacement required between the two stable positions. Two families of designs were considered: those where the actuator was integral to the device and those where it remained in contact only during actuation. Mechanism designs are presented and are currently in the process of fabrication.

No more rattling: biomechanical evaluation of a hexapod ring fixator free of play

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Markus Greinwald ◽  
Emily K. Bliven ◽  
Alex Trompeter ◽  
Peter Augat
Keyword(s):  
Mechanical Performance ◽  
Steel Frame ◽  
Ball Joint ◽  
Universal Joint ◽  
Ring Fixator ◽  
Low Weight ◽  
Biomechanical Evaluation ◽  
Axial Fracture ◽  
Ball Joints ◽  
Universal Joints

Abstract Hexapod-ring-fixators have a characteristic rattling sound during load changes due to play in the hexapod struts. This play is perceived as unpleasant by patients and can lead to frame instability. Using slotted-ball-instead of universal-joints for the ring-strut connection could potentially resolve this problem. The purpose of the study was to clarify if the use of slotted-ball-joints reduces play and also fracture gap movement. A hexapod-fixator with slotted-ball-joints and aluminum struts (Ball-Al) was compared to universal-joint-fixators with either aluminum (Uni Al) or steel struts (Uni Steel). Six fixator frames each were loaded in tension, compression, torsion, bending and shear and mechanical performance was analyzed in terms of movement, stiffness and play. The slotted-ball-joint fixator was the only system without measurable axial play (<0.01 mm) compared to Uni-Al (1.2 ± 0.1) mm and Uni-Steel (0.6 ± 0.2) mm (p≤0.001). In both shear directions the Uni-Al had the largest play (p≤0.014). The resulting axial fracture gap movements were similar for the two aluminum frames and up to 25% smaller for the steel frame, mainly due to the highest stiffness found for the Uni-Steel in all loading scenarios (p≤0.036). However, the Uni-Steel construct was also up to 29% (450 g) heavier and had fewer usable mounting holes. In conclusion, the slotted-ball-joints of the Ball-Al fixator reduced play and minimized shear movement in the fracture while maintaining low weight of the construct. The heavier and stiffer Uni-Steel fixator compensates for existing play with a higher overall stiffness.

A Simple and Accurate Method for Determining Large Deflections in Compliant Mechanisms Subjected to End Forces and Moments

1998 ◽  
Vol 120 (3) ◽  
pp. 392-400 ◽  
Author(s):  
A. Saxena ◽  
S. N. Kramer
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Elliptic Integral ◽  
Beam Equation ◽  
Large Deflections ◽  
Euler Beam ◽  
Body Model ◽  
Rigid Body Model ◽  
Analysis And Synthesis

Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads. Because of this fact, traditional methods of deflection analysis do not apply. Since the nonlinearities introduced by these large deflections make the system comprising such members difficult to solve, parametric deflection approximations are deemed helpful in the analysis and synthesis of compliant mechanisms. This is accomplished by representing the compliant mechanism as a pseudo-rigid-body model. A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms. In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads. A numerical integration technique using quadrature formulae has been employed to solve the large deflection Bernoulli-Euler beam equation for the tip deflection. Implementation of this scheme is simpler than the elliptic integral formulation and provides very accurate results. An example for the synthesis of a compliant mechanism using the proposed model is also presented.

A Simple and Accurate Method for Determining Large Deflections in Complaint Mechanisms Subjected to End Forces and Moments

1998 ◽  
Author(s):  
A. Saxena ◽  
Steven N. Kramer
Keyword(s):  
Rigid Body ◽  
Numerical Integration ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Beam Equation ◽  
Integration Scheme ◽  
Large Deflections ◽  
Body Model ◽  
Rigid Body Model ◽  
Analysis And Synthesis

Abstract Compliant members in flexible link mechanisms undergo large deflections when subjected to external loads for which, traditional methods of deflection analysis do not apply Nonlinearities introduced by these large deflections make the system comprising such members difficult to solve Parametric deflection approximations are then deemed helpful in the analysis and synthesis of compliant mechanisms This is accomplished by seeking the pseudo-rigid-body model representation of the compliant mechanism A wealth of analysis and synthesis techniques available for rigid-body mechanisms thus become amenable to the design of compliant mechanisms In this paper, a pseudo-rigid-body model is developed and solved for the tip deflection of flexible beams for combined end loads with positive end moments A numerical integration technique using quadrature formulae has been employed to solve the nonlinear Bernoulli-Euler beam equation for the tip deflection Implementation of this scheme is relatively simpler than the elliptic integral formulation and provides nearly accurate results Results of the numerical integration scheme are compared with the beam finite element analysis An example for the synthesis of a compliant mechanism using the proposed model is also presented.

Type Synthesis of Compliant Mechanisms Employing a Simplified Approach to Segment Type

1994 ◽  
Author(s):  
Morgan D. Murphy ◽  
Ashok Midha ◽  
Larry L. Howell
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Type Synthesis ◽  
Simplified Approach ◽  
Design Procedures ◽  
Synthesis Techniques ◽  
Design Solutions ◽  
Synthesis Methodology

Abstract The formulation of design procedures for rigid-body mechanisms has benefited from the application of type-synthesis techniques. Therefore, with modifications to allow for inclusions of compliance, type synthesis is seen as a useful tool in the design of compliant mechanisms. Previous efforts have developed methods that result in a large number of possible design solutions to a given problem. This paper deals primarily with the development of a simplified compliant-mechanism type-synthesis methodology that limits the number of design solutions considered. The techniques are derived by modifying existing compliant mechanism type-synthesis techniques to yield a simpler model with greater pragmatic value.

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