Kinetostatic Modeling of Planar Compliant Mechanisms with Flexible Beams, Linear Sliders, Multinary Rigid Links and Multiple Loops

2021 ◽  
pp. 1-18
Author(s):  
I-Ting Chi ◽  
Pei-Lun Chang ◽  
Ngoc Dang Khoa Tran ◽  
Dung-An Wang
Keyword(s):  
Finite Element ◽  
Compliant Mechanisms ◽  
Building Blocks ◽  
Static Equilibrium ◽  
Finite Element Analyses ◽  
Equilibrium Conditions ◽  
Flexible Beams ◽  
Beam Type ◽  
Constraint Model

Abstract This paper presents kinetostatic models of planar compliant mechanisms with multinary rigid links, multinary joints, sliders and multiple loops based on the chained beam constraint model. The focus is on modelling of several building blocks of the beam type compliant mechanisms to aid in their design. The modelling approaches are based on the loop closure equations and the static equilibrium conditions. Models of the multinary rigid links, multinary joints, sliders are presented. As a result, the kinetostatic models of the compliant mechanisms can be systematically formulated by using these building blocks. Several mechanisms constructed by the building blocks are modelled and verified by finite element analyses. A case study is provided to demonstrate the application of the developed models. These models pave the way for versatile applications of the chained beam constraint model for the design and analysis of beam type planar compliant mechanisms.

Modeling Large Spatial Deflections of Slender Bisymmetric Beams in Compliant Mechanisms Using Chained Spatial-Beam Constraint Model

2016 ◽  
Vol 8 (4) ◽  
Author(s):  
Guimin Chen ◽  
Ruiyu Bai
Keyword(s):  
Finite Element Analysis ◽  
Compliant Mechanisms ◽  
Research Community ◽  
Nonlinear Finite Element ◽  
Nonlinear Constraint ◽  
Element Analysis ◽  
Flexible Beams ◽  
Spatial Beams ◽  
Spatial Beam ◽  
Constraint Model

Modeling large spatial deflections of flexible beams has been one of the most challenging problems in the research community of compliant mechanisms. This work presents a method called chained spatial-beam constraint model (CSBCM) for modeling large spatial deflections of flexible bisymmetric beams in compliant mechanisms. CSBCM is based on the spatial-beam constraint model (SBCM), which was developed for the purpose of accurately predicting the nonlinear constraint characteristics of bisymmetric spatial beams in their intermediate deflection range. CSBCM deals with large spatial deflections by dividing a spatial beam into several elements, modeling each element with SBCM, and then assembling the deflected elements using the transformation defined by Tait–Bryan angles to form the whole deflection. It is demonstrated that CSBCM is capable of solving various large spatial deflection problems either the tip loads are known or the tip deflections are known. The examples show that CSBCM can accurately predict large spatial deflections of flexible beams, as compared to the available nonlinear finite element analysis (FEA) results obtained by ansys. The results also demonstrated the unique capabilities of CSBCM to solve large spatial deflection problems that are outside the range of ansys.

The Effect of Joint Flexibility on the Torsion of a Vehicle Body

1982 ◽  
Vol 196 (1) ◽  
pp. 191-197 ◽  
Author(s):  
P W Sharman
Keyword(s):  
Finite Element ◽  
Cross Section ◽  
Theoretical Estimate ◽  
Element Model ◽  
Vehicle Body ◽  
Finite Element Analyses ◽  
Joint Flexibility ◽  
Theoretical Predictions ◽  
Plane Frame ◽  
Beam Type

Experiments on thin fabricated box members in a tee joint configuration revealed deformations which could not be correlated with beam-type models, even when spring elements were introduced at the joint. The behaviour was also observed in finite element analyses of the joints. Part of the cab structure of a heavy goods vehicle which formed a plane frame with fabricated members of closed cross-section was tested in torsion and the stiffness compared with theoretical predictions. The application of classical beam and torsional theory gave a result which was approximately ten times the experimental value. A further theoretical estimate, which included the joint flexibility as predicted by a finite element model of the localized region at the joint, gave an improved result which was 26 per cent higher than the experimental value.

scholarly journals Determination of the Strain-Free Configuration of Multispan Cable

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Chuancai Zhang ◽  
Qiang Guo ◽  
Xinhua Zhang
Keyword(s):  
Finite Element ◽  
Geometric Model ◽  
Static Equilibrium ◽  
Equilibrium Conditions ◽  
Constraint Equations ◽  
Asymptotic Shape ◽  
Geometric Conditions ◽  
End Conditions

For building a reasonable finite element geometric model, a method is proposed to determine the strain-free configuration of the multispan cable. The geometric conditions (the end conditions and the unstretched length conditions) as constraints for the configuration of multispan cable are given. Additionally, asymptotic static equilibrium conditions are given for determining the asymptotic shape of the multispan cable. By solving these constraint equations, a set of parameters are determined and then the strain-free configuration of multispan cable is determined. The method reported in this paper provides a technique for building reasonable FEA geometric model of multispan cables. Finally, a three-span cable is taken as example to illustrate the effectiveness of the method, and the computed results are validated via the software ADINA.

Chained Beam-Constraint-Model (CBCM): A Powerful Tool for Modeling Large and Complicated Deflections of Flexible Beams in Compliant Mechanisms

2014 ◽  
Author(s):  
Fulei Ma ◽  
Guimin Chen
Keyword(s):  
Large Deflection ◽  
Compliant Mechanisms ◽  
Research Community ◽  
The Other ◽  
New Method ◽  
Flexible Beam ◽  
Large Deflections ◽  
Flexible Beams ◽  
Constraint Model

Modeling large deflections has been one of the most fundamental problems in the research community of compliant mechanisms. Although many methods are available, there still exists a need for a method that is simple, accurate, and can be applied to a vast variety of large deflection problems. Based on the beam constraint model (BCM), we propose a new method for modeling large deflections called chained BCM (CBCM), which divides a flexible beam into a few elements and models each element by BCM. It is demonstrated that CBCM is capable of modeling various large and complicated deflections of flexible beams in compliant mechanisms. In general, CBCM obtains accurate results with no more than 6 BCM elements, thus is more efficient than most of the other discretization-based methods.

Modeling Large Spatial Deflections of Slender Bisymmetric Beams in Compliant Mechanisms Using Chained Spatial-Beam-Constraint-Model (CSBCM)

2015 ◽  
Author(s):  
Guimin Chen ◽  
Ruiyu Bai
Keyword(s):  
Compliant Mechanisms ◽  
Research Community ◽  
Nonlinear Constraint ◽  
Flexible Beams ◽  
Spatial Beams ◽  
Spatial Beam ◽  
Constraint Model

Modeling large spatial deflections of flexible beams has been one of the most challenging problems in the research community of compliant mechanisms. This work presents a method called chained spatial-beam-constraint-model (CSBCM) for modeling large spatial deflections of flexible bisymmetric beams in compliant mechanisms. CSBCM is based on the spatial beam constraint model (SBCM), which was developed for the purpose of accurately predicting the nonlinear constraint characteristics of bisymmetric spatial beams in their intermediate deflection range. CSBCM deals with large spatial deflections by dividing a spatial beam into several elements, modeling each element with SBCM, and then assembling the deflected elements using the transformation defined by Tait-Bryan angles to form the whole deflection. It is demonstrated that CSBCM is capable of solving various large spatial deflection problems whether the tip loads are known or the tip deflections are known. The examples show that CSBCM can accurately predict the large spatial deflections of flexible beams, as compared to the available nonlinear FEA results obtained by ANSYS. The results also demonstrated the unique capabilities of CSBCM to solve large spatial deflection problems that are outside the range of ANSYS.

Decomposition-Based Assembly Synthesis of Space Frame Structures Using Joint Library

2004 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
Structural Characteristics ◽  
Finite Element Analyses ◽  
Space Frame ◽  
Multi Objective Genetic Algorithm ◽  
Joint Location ◽  
The Cross

This paper presents a method for identifying the optimal designs of components and joints in the space frame body structures of passenger vehicles considering structural characteristics, manufacturability and assembleability. Dissimilar to our previous work based on graph decomposition, the problem is posed as a simultaneous determination of the locations and types of joints in a structure and the cross sections of the joined structural frames, selected from a predefined joint library. The joint library is a set of joint designs containing the geometry of the feasible joints at each potential joint location and the cross sections of the joined frames, associated with their structural characteristics as equivalent torsional springs obtained from the finite element analyses of the detailed joint geometry. Structural characteristics of the entire structure are evaluated by finite element analyses of a beam-spring model constructed from the selected joints and joined frames. Manufacturability and assembleability are evaluated as the manufacturing and assembly costs estimated from the geometry of the components and joints, respectively. The optimization problem is solved by a multi-objective genetic algorithm using a direct crossover. A case study on an aluminum space frame (ASF) of a middle size passenger vehicle is discussed.

Fixture Layout Design and Optimization of Sheet Metal Assembly Based on Genetic Algorithm for Optimization Toolbox

2016 ◽  
Author(s):  
Yanfeng Xing ◽  
Fang Wang ◽  
Qing Ji
Keyword(s):  
Genetic Algorithm ◽  
Finite Element ◽  
Sheet Metal ◽  
Layout Optimization ◽  
Finite Element Analyses ◽  
Design And Optimization ◽  
Fixture Layout ◽  
Fixture Layout Optimization ◽  
Dimensional Variation

Fixture layout can affect deformation and dimensional variation of sheet metal assemblies. Conventionally, the assembly dimensions are simulated using a large number of finite element analyses, and fixture layout optimization needs significant user intervention and unaffordable iterations of finite element analyses. This paper therefore proposes a fully automated and efficient method of fixture layout optimization based on the combination of 3DCS simulation (for dimensional analyses) and GAOT, a genetic algorithm in optimization toolbox in MATLAB. The locating points, the key elements of a fixture layout, are selected from a much smaller candidate pool thanks to our proposed manufacturing constraints based filtering methods and thus the computational efficiency is greatly improved. Since MATLAB macro commands of 3DCS have been developed to calculate assembly dimensions, the optimization process is fully automated. A case study of inner hood is applied to demonstrate the proposed method. The results show that the proposed method is suitable for generating the optimal fixture layout with excellent efficiency for engineering applications.

Decomposition-Based Assembly Synthesis of Space Frame Structures Using Joint Library

2004 ◽  
Vol 128 (1) ◽  
pp. 57-65 ◽  
Author(s):  
Naesung Lyu ◽  
Kazuhiro Saitou
Keyword(s):  
Finite Element ◽  
Cross Sections ◽  
Structural Characteristics ◽  
Finite Element Analyses ◽  
Space Frame ◽  
Passenger Vehicles ◽  
Joint Location ◽  
The Cross

This paper presents a method for identifying the optimal designs of components and joints in the space frame body structures of passenger vehicles considering structural characteristics, manufacturability, and assembleability. Dissimilar to our previous work based on graph decomposition, the problem is posed as a simultaneous determination of the locations and types of joints in a structure and the cross sections of the joined structural frames, selected from a predefined joint library. The joint library is a set of joint designs containing the geometry of the feasible joints at each potential joint location and the cross sections of the joined frames, associated with their structural characteristics as equivalent torsional springs obtained from the finite element analyses of the detailed joint geometry. Structural characteristics of the entire structure are evaluated by finite element analyses of a beam-spring model constructed from the selected joints and joined frames. Manufacturability and assembleability are evaluated as the manufacturing and assembly costs estimated from the geometry of the components and joints, respectively. The optimization problem is solved by a multiobjective genetic algorithm using a direct crossover. A case study on an aluminum space frame of a midsize passenger vehicle is discussed.

Failure Behavior of Colonies of Corrosion Defects Composed of Symmetrically Arranged Defects

2006 ◽  
Author(s):  
Adilson C. Benjamin ◽  
Edmundo Q. de Andrade ◽  
Breno P. Jacob ◽  
Leonardo C. Pereira ◽  
Paulo R. S. Machado
Keyword(s):  
Finite Element ◽  
Parametric Study ◽  
Effective Area ◽  
Large Strains ◽  
Failure Behavior ◽  
Finite Element Models ◽  
Finite Element Analyses ◽  
Contour Plots ◽  
Corrosion Defects

This paper presents a case study on the failure behavior of four colonies of corrosion defects using solid Finite Element models. These analyses accounted for large strains and displacements, stress-stiffening and material nonlinearity. Colonies 1 and 2 are each composed of two longitudinally aligned defects. Colonies 3 and 4 are each composed of four defects (two longitudinally aligned defects and two circumferentially aligned defects) arranged in a rhombus shape. For each of the four colonies a parametric study is performed in which the longitudinal spacing sL between the two defects longitudinally aligned is varied from a small value (sL)min to a large value (sL)max. Based on the results obtained the failure behavior of each colony is described and illustrated by contour plots of stresses. The failure pressures predicted by the Finite Element analyses are compared with those predicted by six assessments methods, namely: the ASME B31G method, the RSTRENG 085dL method, the DNV RP-F101 method for single defects (Part B), the RPA method, the RSTRENG Effective Area method and the DNV RP-F101 method for interacting defects (Part B).

Sign in / Sign up

Export Citation Format

Share Document