scholarly journals Modeling the Bending Behavior of Fiber-Reinforced Pneumatic Actuators Using a Pseudo-Rigid-Body Model

2019 ◽  
Vol 11 (3) ◽  
Author(s):  
Sreeshankar Satheeshbabu ◽  
Girish Krishnan
Keyword(s):  
Rigid Body ◽  
Parametric Estimation ◽  
Fiber Reinforced ◽  
Accurate Analysis ◽  
Element Analysis ◽  
Pneumatic Actuators ◽  
Rigid Body Model ◽  
Optimization Routine ◽  
External Forces ◽  
Deformation Patterns

Abstract Fiber reinforced elastomeric enclosures (FREEs) are soft pneumatic representative elements that can form the basis for building soft self-actuating structures/mechanisms. When placed in different configurations, they exhibit unique stroke amplification characteristics that can be leveraged to create interesting deformation patterns. Such deformations occur as a combination of axial and bending deflection due to internal pressurization and external forces. This paper presents a lumped reduced-order model that enables quick and accurate analysis of mechanisms made from FREEs grouped as a system. The model proposed is a modified four-spring pseudo-rigid-body (PRB) model that effectively captures the axial and bending stiffnesses of contracting FREEs. Parametric estimation of the model is performed using a multistart optimization routine to fit the PRB model with results from experiments and finite element analysis (FEA). The model is also generalized and statistically verified for FREEs with different fiber angles, length-to-diameter ratios, and different actuation pressures. Finally, efficacy of the approach is validated through three case studies that involve a planar arrangement of FREEs at different orientations.

Kinematic Synthesis of a D-Drive MEMS Device With Rigid-Body Replacement Method

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Paolo Sanò ◽  
Matteo Verotti ◽  
Paolo Bosetti ◽  
Nicola P. Belfiore
Keyword(s):  
Rigid Body ◽  
Experimental Testing ◽  
Micro Electro Mechanical System ◽  
Element Analysis ◽  
Kinematic Synthesis ◽  
Replacement Method ◽  
Rigid Body Model ◽  
Mems Device ◽  
Conjugate Surfaces ◽  
Line Path

In this paper, a microsystem with prescribed functional capabilities is designed and simulated. In particular, the development of a straight line path generator micro electro mechanical system (MEMS) device is presented. A new procedure is suggested for avoiding branch or circuit problems in the kinematic synthesis problem. Then, Ball's point detection is used to validate the obtained pseudo-rigid body model (PRBM). A compliant MEMS device is obtained from the PRBM through the rigid-body replacement method by making use of conjugate surfaces flexure hinges (CSFHs). Finally, the functional capability of the device is investigated by means of finite element analysis (FEA) simulations and experimental testing at the macroscale.

scholarly journals Design and Validation of a Single-SOI-Wafer 4-DOF Crawling Microgripper

Micromachines ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 376 ◽  
Author(s):  
Matteo Verotti ◽  
Alvise Bagolini ◽  
Pierluigi Bellutti ◽  
Nicola Pio Belfiore
Keyword(s):  
Finite Element Analysis ◽  
Rigid Body ◽  
Compliant Mechanism ◽  
Silicon On Insulator ◽  
Element Analysis ◽  
Deep Reactive Ion Etching ◽  
Theoretical Simulation ◽  
Body Model ◽  
Replacement Method ◽  
Rigid Body Model

This paper deals with the manipulation of micro-objects operated by a new concept multi-hinge multi-DoF (degree of freedom) microsystem. The system is composed of a planar 3-DoF microstage and of a set of one-DoF microgrippers, and it is arranged is such a way as to allow any microgripper to crawl over the stage. As a result, the optimal configuration to grasp the micro-object can be reached. Classical algorithms of kinematic analysis have been used to study the rigid-body model of the mobile platform. Then, the rigid-body replacement method has been implemented to design the corresponding compliant mechanism, whose geometry can be transferred onto the etch mask. Deep-reactive ion etching (DRIE) is suggested to fabricate the whole system. The main contributions of this investigation consist of (i) the achievement of a relative motion between the supporting platform and the microgrippers, and of (ii) the design of a process flow for the simultaneous fabrication of the stage and the microgrippers, starting from a single silicon-on-insulator (SOI) wafer. Functionality is validated via theoretical simulation and finite element analysis, whereas fabrication feasibility is granted by preliminary tests performed on some parts of the microsystem.

A Family of Butterfly Flexural Joints: Q-LITF Pivots

2011 ◽  
Author(s):  
Xu Pei ◽  
Jingjun Yu ◽  
Shusheng Bi ◽  
Guanghua Zong
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rigid Body ◽  
Rigid Bodies ◽  
The Other ◽  
Element Analysis ◽  
Leaf Type ◽  
Center Shift ◽  
Body Model ◽  
Rigid Body Model

The Leaf-type Isosceles-Trapezoidal Flexural (LITF) pivot consists of two compliant beams and two rigid-bodies. For a single LITF pivot, the range of motion is small while the center-shift is relatively large. The capability of performance can be improved greatly by the combination of four LITF pivots. Base on the pseudo-rigid-body model (PRBM) of a LITF pivot, a method to construct the Quadri-LITF pivots is presented by regarding a single LITF pivot (or double-LITF pivot) as a the configurable flexure module. Ten types of Q-LITF pivots are synthesized. Compared with the single LIFT pivot, the stroke becomes larger, and stiffness becomes smaller. Four of them have the increased center-shift. The other four have the decreased center-shift. One of the quadruple LITF pivots is selected as the examples to explain the proposed method. The comparison between PRBM and Finite Element Analysis (FEA) result shows the validity and effectiveness of the method.

Force-Displacement Model of the FlexSuRe™ Spinal Implant

2010 ◽  
Author(s):  
Eric Stratton ◽  
Larry Howell ◽  
Anton Bowden
Keyword(s):  
Rigid Body ◽  
Virtual Work ◽  
Implant Design ◽  
Element Analysis ◽  
Spinal Implant ◽  
Body Model ◽  
Flexion Extension ◽  
Rigid Body Model ◽  
Displacement Model ◽  
Force Displacement

This paper presents modeling of a novel compliant spinal implant designed to reduce back pain and restore function to degenerate spinal disc tissues as well as provide a mechanical environment conducive to healing of the tissues. Modeling was done through the use of the pseudo-rigid-body model. The pseudo-rigid-body model is a 3 DOF mechanism for flexion-extension (forward-backward bending) and a 5 DOF mechanism for lateral bending (side-to-side). These models were analyzed using the principle of virtual work to obtain the force-deflection response of the device. The model showed good correlation to finite element analysis and experimental results. The implant may be particularly useful in the early phases of implant design and when designing for particular biological parameters.

scholarly journals Compliant Mechanism Road Bicycle Brake: A Rigid-Body Replacement Case Study

2011 ◽  
Author(s):  
Brian M. Olsen ◽  
Larry L. Howell ◽  
Spencer P. Magleby
Keyword(s):  
Rigid Body ◽  
High Performance ◽  
Compliant Mechanisms ◽  
Compliant Mechanism ◽  
Element Analysis ◽  
Low Weight ◽  
Rigid Body Model ◽  
Compliant Mechanism Design

This paper demonstrates rigid-body replacement synthesis in the design a mechanism with known design objectives. The design of high-performance bicycle brakes is complicated by a variety of competing design objectives, including increased performance and low weight. But this challenge also provides a good case study to demonstrate the design of compliant mechanisms to replace traditional rigid-link mechanisms. This paper briefly reviews current road brake designs, demonstrates the use of rigid-body replacement synthesis to design a compliant mechanism, and illustrates the combination of compliant mechanism design tools. The resulting concept was generated from the modified dual-pivot brake design and is a partially compliant mechanism where one pin has the dual role of a joint and a mounting pin. The pseudo-rigid-body model, finite element analysis, and optimization algorithms are used to generate design dimensions, and designs are considered for both titanium and E-glass flexures. The resulting design has the potential of reducing the part count and overall weight while maintaining a performance similar to the benchmark.

Spatial-Beam Large-Deflection Equations and Pseudo-Rigid-Body Model for Axisymmetric Cantilever Beams

2011 ◽  
Author(s):  
Issa A. Ramirez ◽  
Craig P. Lusk
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Rigid Body ◽  
Three Dimensional ◽  
Vertical Axis ◽  
Analysis Model ◽  
Element Analysis ◽  
Body Model ◽  
Straight Beam ◽  
Rigid Body Model

The kinematic equations for approximating the deflection of a three-dimensional cantilever beam were developed. The numerical equations were validated with a Finite Element Analysis program. With these equations, a pseudo-rigid-body model (PRBM) for an axisymmetric straight beam was developed. The axisymmetric PRBM consists of a spherical joint connecting two rigid links. The location of the deformed end of the beam is determined by two angles and the characteristic radius factor. The angle of the beam with respect to the vertical axis depends on the direction of the force with respect to the undeformed coordinate system. The Pearson’s correlation coefficient for the Finite Element Analysis model and the numerical integration is 0.952.

scholarly journals Adaptive pseudo-rigid-body model for generalized cross-spring pivots under combined loads

2020 ◽  
Vol 12 (12) ◽  
pp. 168781402096653
Author(s):  
Zhongzhou Wang ◽  
Haixuan Sun ◽  
Bidou Wang ◽  
Peng Wang
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Parametric Design ◽  
Optimization Techniques ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
Combined Loads ◽  
Rigid Body Model ◽  
Instantaneous Center ◽  
Constraint Model

Generalized cross-spring pivots (CSPs) are widely used as revolute joints in precision machinery. However, pseudo-rigid-body (PRB) models cannot capture the parasitic motions of a generalized CSP exactly under combined loads; moreover, the characteristic parameters used in PRB methods must be recomputed using optimization techniques. In this study, we develop two simple and accurate PRB models for generalized CSPs. First, a PRB method for a beam is developed based on the beam constraint model and the instantaneous center model, where the beam is modeled as two rigid links joined at a pivot via a torsion spring. Subsequently, two PRB models of the generalized CSP, comprising a four-bar model for accuracy and a pin-joint model for stiffness, are constructed based on a kinematic analysis using the proposed PRB method. A deflection characteristic analysis is then conducted to determine the relationship between the proposed model and the existing models. Finally, the PRB models for the pivot under the action of combined loads are validated via finite element analysis. The error evaluation indicates that the proposed PRB models are more accurate than the results from existing methods. The PRB models proposed here can be used in parametric design of compliant mechanisms.

A Pseudo-Rigid-Body Model for Spherical Mechanisms: The Kinematics and Stiffness of a Compliant Curved Beam

2008 ◽  
Author(s):  
Alejandro Leo´n ◽  
Saurabh Jagirdar ◽  
Craig P. Lusk
Keyword(s):  
Rigid Body ◽  
Curved Beam ◽  
Beam Angle ◽  
Element Analysis ◽  
Body Model ◽  
Spherical Mechanisms ◽  
Characteristic Radius ◽  
Rigid Body Model ◽  
Spherical Mechanism ◽  
Spherical Motion

A pseudo-rigid-body model (PRBM) which describes a class of curved compliant beams in terms of spherical mechanism kinematics was developed. The topology of the spherical compliant segment and its rigid-body equivalent were chosen to be analogous to planar models. The nomenclature for the spherical PRBM was also chosen to facilitate comparison with planar models. The motion of the compliant segment was calculated Finite Element Analysis and the PRBM parameters were determined. The characteristic radius and parametric angle coefficient were found to decrease as the angle subtended by the beam increases. The kinematic and elastic parameterization limits of the model increase with increasing beam angle. The stiffness of the beam is described by two separate spring elements, which describe the appropriate combination of moment and force which produces spherical motion. A previous planar PRBM is shown to be the small angle limit of the new spherical PRBM.

scholarly journals A Versatile 3R Pseudo-Rigid-Body Model for Initially Curved and Straight Compliant Beams of Uniform Cross Section

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Venkatasubramanian Kalpathy Venkiteswaran ◽  
Hai-Jun Su
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Element Analysis ◽  
Revolute Joints ◽  
Rigid Body Model ◽  
Uniform Cross Section ◽  
Optimized Model ◽  
Force Mechanism ◽  
Parameter Values ◽  
Constant Force Mechanism

Rigid-body discretization of continuum elements was developed as a method for simplifying the kinematics of otherwise complex systems. Recent work on pseudo-rigid-body (PRB) models for compliant mechanisms has opened up the possibility of using similar concepts for synthesis and design, while incorporating various types of flexible elements within the same framework. In this paper, an idea for combining initially curved and straight beams within planar compliant mechanisms is developed to create a set of equations that can be used to analyze various designs and topologies. A PRB model with three revolute joints is derived to approximate the behavior of initially curved compliant beams, while treating straight beams as a special case (zero curvature). The optimized model parameter values are tabled for a range of arc angles. The general kinematic and static equations for a single-loop mechanism are shown, with an example to illustrate accuracy for shape and displacement . Finally, this framework is used for the design of a compliant constant force mechanism to illustrate its application, and comparisons with finite element analysis (FEA) are provided for validation.

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