Modeling and Analysis of Leaf Spring Based Double Parallel-Guiding Mechanism Considering Thermal Effect

2019 ◽  
Author(s):  
Shuaishuai Lu ◽  
Peng Yan
Keyword(s):  
Thermal Effect ◽  
Temperature Variation ◽  
Compliant Mechanisms ◽  
Parametric Method ◽  
Leaf Spring ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Proposed Model ◽  
Constraint Model ◽  
And Control

Abstract In the present paper, we take the leaf spring based double parallel-guiding mechanism (DPGM) as a particular case study to investigate a parametric model by considering the stress stiffening effect of the temperature variation based on the beam constraint model (BCM). In particular, a model with the temperature variation term of the DPGM is derived by incorporating the elastic stretch induced by the thermal effect of the leaf spring flexure into the BCM. Different from the traditional BCM, the compliance calculated by the established model is no longer only affected by the external loads, but the thermal deformation generated by the temperature variation. Therefore the derived model can describe both the load-nonlinearity and the thermal-nonlinearity. Based on the analysis results of a basic parallelogram module (BPM), we obtain a model of the DPGM, and the finite element analysis (FEA) method is adopted to verify the proposed model. The proposed model is a general parametric method to characterize the mechanical property of the DPGM, which can be further explored to support the optimization and control of motion systems composed of leaf spring based compliant mechanisms.

Modeling and Analysis of Beam Flexure Based Double Parallel Guiding Mechanisms: A Modified Pseudo-Rigid-Body Approach

2016 ◽  
Author(s):  
Pengbo Liu ◽  
Peng Yan
Keyword(s):  
Rigid Body ◽  
Axial Force ◽  
Compliant Mechanisms ◽  
Parametric Method ◽  
Nonlinear Effects ◽  
Element Analysis ◽  
Modeling And Analysis ◽  
Design And Optimization ◽  
Accurate Model ◽  
Characteristic Radius

In the present paper, we take the complaint double parallel guiding mechanism as a particular case study to investigate a modified pseudo-rigid-body (MPRB) modeling approach for beam flexure based mechanisms by considering the nonlinear effects of the center-shift and the load-stiffening. In particular, through incorporating the elastic stretch of the beam flexure into the linear Bernoulli-Euler equation, a more accurate model of the beam flexure is derived. Accordingly an MPRB model for a beam flexure is established, which consists of two rigid links joined at a revolute joint and a torsional spring along the beam. Different from traditional PRB model, the location of the torsion spring is not only determined by the characteristic radius factor, but also a purely elastic stretch under the action of the axial force. Meanwhile, both the characteristic radius factor and the equivalent stiffness of the beam flexure are no longer constant values, but affected by the applied general tip load, especially the axial force. Based on the analysis results of a beam flexure, we obtain a more accurate model of the double parallel guiding mechanisms, which is further verified by the finite element analysis (FEA) results. The proposed MPRB model provides a more parametric method to predict the performance characteristics such as deformation capability, stiffness variation, as well as error motions of the beam flexure based complaint mechanisms, and offers a new look into the design and optimization of beam-based compliant mechanisms.

Analytical Modeling and Analysis of an Annulus-Shaped Flexural Pivot

2012 ◽  
Author(s):  
Yanbin Yao ◽  
Shusheng Bi ◽  
Hongzhe Zhao
Keyword(s):  
Analytical Modeling ◽  
Compliant Mechanisms ◽  
Bending Moment ◽  
Vertical Force ◽  
Rotational Stiffness ◽  
Element Analysis ◽  
Rotational Angle ◽  
Modeling And Analysis ◽  
The Finite Element Analysis ◽  
Constraint Model

Annulus-shaped flexural pivots (ASFP), composed of three or more identical leaves that are symmetrically arrayed in an annulus, can be used widely in compliant mechanisms for their excellent performances. This paper proposes the accurate load-rotation models of ASFP with three straight leaves, which include the load cases of bending moment combined with horizontal force and vertical force. Firstly, the load-rotation models of ASFP are derived based on the Beam Constraint Model (BCM). Then, the rotational stiffness and buckling characteristics are analyzed based on the derived models. Finally, the accuracy of the models is validated by the finite element analysis (FEA). The relative error of the load-rotation models is within 7% for various load cases even if the rotational angle reaches 0.07 (4°). The results show that the models are accurate enough to be used for initial parametric designing of ASFP.

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.

scholarly journals Multi-terrain Quadrupedal-wheeled Robot Mechanism: Design, Modeling, and Analysis

2020 ◽  
Vol 5 (12) ◽  
pp. 24-33
Author(s):  
Eric Gratton ◽  
Mbadiwe Benyeogor ◽  
Kosisochukwu Nnoli ◽  
Oladayo Olakanmi ◽  
Liam Wolf ◽  
...  
Keyword(s):  
Structural Integrity ◽  
Mechanical Design ◽  
Element Analysis ◽  
Active Suspensions ◽  
Modeling And Analysis ◽  
Drive Mechanism ◽  
Wheel Drive ◽  
Wheeled Robot ◽  
Mathematical Equations ◽  
And Control

For a robot to navigate in terrains of rough and uneven topographies, its drives and controllers must generate and control large mechanical power with great precision. This paper is aimed at developing an autonomous robot with active-suspensions in form of a hybrid quadrupedal-wheel drive mechanism. This involves a computational approach to optimizing the development cost without compromising the system’s performance. Using the Solidworks CAD tool, auxiliary components were designed and integrated with the bed structure to form an actively suspended robot drive mechanism. Also, using the S-Math Computing tool, the robot’s suspension system was optimized, employing a four-bar mechanism. To enhance the compatibility of this design with the intended controller, some mathematical equations and numerical validations were formulated and solved. These included the modeling of tip-over stability and skid steering, the trendline equations for computing the angular positions of the suspension servomotors, and the computation of R2– values for determining the accuracy of these trendline equations. Using finite element analysis (FEA), we simulated the structural integrity of key sub-components of the final structure. The results show that our mechanical design is appropriate for developing an actively suspended robot that can efficiently navigate in different terrestrial sites and topographies.

The Compliant A-Arm Suspension

Aerospace ◽  
2003 ◽  
Author(s):  
Timothy Allred ◽  
Larry L. Howell ◽  
Spencer P. Magleby ◽  
Robert H. Todd
Keyword(s):  
Compliant Mechanisms ◽  
Commercial Application ◽  
Leaf Spring ◽  
Large Deflections ◽  
Element Analysis ◽  
Performance Variables ◽  
Body Model ◽  
Small Deflection ◽  
Rigid Body Model ◽  
Depth Study

The use compliant mechanisms in a suspension system has been demonstrated with leaf spring mechanisms. In this research a novel compliant configuration called the Compliant A-Arm (C-A-Arm) suspension is selected for in-depth study. Closed-from equations are derived for linear small-deflection stiffness equations. Large deflections are analyzed using finite element analysis. A pseudo-rigid-body model is developed to approximate mechanism deflections and stiffness for large deflections. The results suggest that the C-A-Arm configuration may be a viable suspension alternative for future commercial application. In addition, this configuration offers a number of performance variables that could be the basis for an active control system. This paper represents a necessary first step in modeling this new configuration.

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.

scholarly journals A modified pseudo-rigid-body modeling approach for compliant mechanisms with fixed-guided beam flexures

2017 ◽  
Vol 8 (2) ◽  
pp. 359-368 ◽  
Author(s):  
Pengbo Liu ◽  
Peng Yan
Keyword(s):  
Rigid Body ◽  
Compliant Mechanisms ◽  
Nonlinear Effects ◽  
Accurate Method ◽  
Element Analysis ◽  
Design And Optimization ◽  
Modeling Approach ◽  
The Finite Element Analysis ◽  
Constraint Model ◽  
Translational Mechanisms

Abstract. In the present paper, we investigate a modified pseudo-rigid-body (MPRB) modeling approach for compliant mechanisms with fixed-guided beam flexures by considering the nonlinear effects of center-shifting and load-stiffening. In particular, a fixed-guided compliant beam is modeled as a pair of fixed-free compliant beams jointed at the inflection point, where each fixed-free beam flexure is further modeled by a rigid link connected with an extension spring by a torsion spring, based on the beam constraint model (BCM). Meanwhile, the characteristic parameters of the proposed MPRB model are no longer constant values, but affected by the applied general tip load, especially the axial force. The developed MPRB modeling method is then applied to the analysis of three common compliant mechanisms (i.e. compound parallelogram mechanisms, bistable mechanisms and 1-DOF translational mechanisms), which is further verified by the finite element analysis (FEA) results. The proposed MPRB model provides a more accurate method to predict the performance characteristics such as deformation capability, stiffness variation, as well as error motions of complaint mechanisms with fixed-guided beam flexures, and offers a new look into the design and optimization of beam-based compliant mechanisms.

Deterministic Design for a Compliant Parallel Universal Joint With Constant Rotational Stiffness

2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Yan Xie ◽  
Jingjun Yu ◽  
Hongzhe Zhao
Keyword(s):  
Compliant Mechanisms ◽  
Experimental Testing ◽  
Rotational Stiffness ◽  
Universal Joint ◽  
Element Analysis ◽  
Rotational Angle ◽  
Constant Stiffness ◽  
Stiffness Model ◽  
Stiffness Characteristics ◽  
Constraint Model

Compliant universal joints have been widely employed in high-precision fields due to plenty of good performance. However, the stiffness characteristics, as the most important consideration for compliant mechanisms, are rarely involved. In this paper, a deterministic design for a constraint-based compliant parallel universal joint with constant rotational stiffness is presented. First, a constant stiffness realization principle is proposed by combination of the freedom and constraint topology (FACT) method and beam constraint model (BCM) to establish a mapping relationship between stiffness characteristics and topology configurations. A parallel universal joint topology is generated by the constant stiffness realization principle. Then, the analytical stiffness model of the universal joint with some permissible approximations is formulated based on the BCM, and geometrical prerequisites are derived to achieve the desired constant rotational stiffness. After that, finite element analysis (FEA), experimental testing, and detailed stiffness analysis are carried out. It turns out that the rotational stiffness of the universal joint can keep constant with arbitrary azimuth angles even if the rotational angle reaches up to ±5 deg. Meanwhile, the acceptable relative errors of rotational stiffness are within 0.53% compared with the FEA results and 2.6% compared with the experimental results, which indicates the accuracy of the theoretical stiffness model and further implies the feasibility of constant stiffness realization principle on guiding the universal joint design.

Optimal Structural Design of Micro-Motion Stage with Stiffness Constraints Using Topology and Sizing Optimization Method

2016 ◽  
Vol 679 ◽  
pp. 55-58
Author(s):  
You Dun Bai ◽  
Zhi Jun Yang ◽  
Xin Chen ◽  
Meng Wang
Keyword(s):  
Compliant Mechanisms ◽  
Optimization Methods ◽  
Flexure Hinge ◽  
Leaf Spring ◽  
Element Analysis ◽  
Sizing Optimization ◽  
Flexure Hinges ◽  
Spring Type ◽  
Micro Motion ◽  
Motion Stage

Flexure hinge is widely used in the compliant mechanisms for precision engineering. Generally, compliant mechanisms with flexure hinges are designed using the analytical stiffness formulas, which increases the design complexity. As the development of finite element analysis (FEA) and optimization methods, it is likely to design the flexure hinges directly using the FEA based numerical optimization methods. This paper developed a leaf spring type flexure hinge based micro-motion stage with specific stiffness constraints. Both topology and sizing optimization methods are used in the design of motion stage. The proposed methods is apply to optimal design formed the leaf spring type flexure hinge for a micro motion stage which serves as a guidance mechanism. Further numerical result shows the good stiffness stability of the refined stage.

On modeling and dynamics of a multiple launch rocket system

2021 ◽  
pp. 095441002098224
Author(s):  
Bo Li ◽  
Xiaoting Rui ◽  
Guoping Wang ◽  
Jianshu Zhang ◽  
Qinbo Zhou
Keyword(s):  
Monte Carlo ◽  
Multibody Systems ◽  
Euler Method ◽  
Dynamics Analysis ◽  
Analysis Problem ◽  
Dynamic Design ◽  
Proposed Model ◽  
And Control ◽  
Rocket System ◽  
Complete Process

Dynamics analysis is currently a key technique to fully understand the dynamic characteristics of sophisticated mechanical systems because it is a prerequisite for dynamic design and control studies. In this study, a dynamics analysis problem for a multiple launch rocket system (MLRS) is developed. We particularly focus on the deductions of equations governing the motion of the MLRS without rockets by using a transfer matrix method for multibody systems and the motion of rockets via the Newton–Euler method. By combining the two equations, the differential equations of the MLRS are obtained. The complete process of the rockets’ ignition, movement in the barrels, airborne flight, and landing is numerically simulated via the Monte Carlo stochastic method. An experiment is implemented to validate the proposed model and the corresponding numerical results.

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