The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Paulo Flores - One of the best experts on this subject based on the ideXlab platform.
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A finite element model of a 3D dry Revolute Joint incorporated in a multibody dynamic analysis
Multibody System Dynamics, 2019Co-Authors: Fernando Isaac, Filipe Marques, Nuno Dourado, Paulo FloresAbstract:In this work a new approach to deal with non-ideal operative aspects of spatial Revolute Joints by means of a three-dimensional finite element analysis (3D-FEA) is presented. The developed model incorporates the inertia of the Joint components and the corresponding material properties. The fact that actual Joint mechanical components present dimensional and geometrical deviations resulting from the assembly process and operative conditions lead to frequent modifications relative to the design conditions that are worth analyzing. Such nonconformities include manufacturing tolerances and assembly errors, thermal effects, local deformations and clearances that directly affect the behavior and reliability of a mechanism, as they are typically at the origin of vibrations, noise and wear. In this work, a comprehensive assessment of the current contact force models implemented in the MultiBody Dynamics (MBD) approach is performed with the aim of understanding its main flaws and weaknesses, validating the need of a new model that is able to evaluate with accuracy the contact forces obtained. Finally, a benchmark problem is presented through a 3D slider–crank mechanism, allowing for the recognition of the differences that exist when the problem is analyzed by means of the MBD and FEM formulations. For this purpose, one of the Joints is modeled as non-ideal, with both radial and axial clearances, the ultimate goal of which is to combine both approaches and, thus establish a crucial and pioneering connection to solve the contact problem.
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nonlinear dynamics and chaotic control of a flexible multibody system with uncertain Joint clearance
Nonlinear Dynamics, 2016Co-Authors: Zhe Wang, Qiang Tian, Paulo FloresAbstract:The nonlinear dynamics of a flexible multibody system with interval clearance size in a Revolute Joint is investigated in this work. The system is modeled by using a unified mesh of absolute nodal coordinate formulation (ANCF), that is, the flexible parts are meshed via the finite elements of the ANCF and the rigid parts are described via the ANCF reference nodes (ANCF-RNs). The kinetic models of all Revolute Joints are formulated by using ANCF reference node (ANCF-RN) coordinates. The influence of the Lund-Grenoble and the modified Coulomb’s friction models on the system dynamics is comparatively studied. The Chebyshev tensor product sampling method is used to generate the samples of the interval clearance size. With the purpose to maintain the continuous contact of the clearance Joint, a modified extended delayed feedback control (EDFC) is used to stabilize the chaotic motion of the flexible multibody system. Finally, the dynamics of a planar slider–crank mechanism with interval clearance size in a Revolute Joint is studied, as a benchmark example, to check the effectiveness of the presented computation method and the modified EDFC.
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a kriging model for dynamics of mechanical systems with Revolute Joint clearances
Journal of Computational and Nonlinear Dynamics, 2014Co-Authors: Zhenhua Zhang, Paulo Flores, Hamid M LankaraniAbstract:Over the past two decades, extensive work has been conducted on the dynamic effect of Joint clearances in multibody mechanical systems. In contrast, little work has been devoted to optimizing the performance of these systems. In this study, the analysis of Revolute Joint clearance is formulated in terms of a Hertzian-based contact force model. For illustration, the classical slider-crank mechanism with a Revolute clearance Joint at the piston pin is presented and a simulation model is developed using the analysis/design software MSC.ADAMS. The clearance is modeled as a pin-in-a-hole surface-to-surface dry contact, with an appropriate contact force model between the Joint and bearing surfaces. Different simulations are performed to demonstrate the influence of the Joint clearance size and the input crank speed on the dynamic behavior of the system with the Joint clearance. In the modeling and simulation of the experimental setup and in the followed parametric study with a slightly revised system, both the Hertzian normal contact force model and a Coulomb-type friction force model were utilized. The kinetic coefficient of friction was chosen as constant throughout the study. An innovative design-of-experiment (DOE)-based method for optimizing the performance of a mechanical system with the Revolute Joint clearance for different ranges of design parameters is then proposed. Based on the simulation model results from sample points, which are selected by a Latin hypercube sampling (LHS) method, a polynomial function Kriging meta-model is established instead of the actual simulation model. The reason for the development and use of the meta-model is to bypass computationally intensive simulations of a computer model for different design parameter values in place of a more efficient and cost-effective mathematical model. Finally, numerical results obtained from two application examples with different design parameters, including the Joint clearance size, crank speed, and contact stiffness, are presented for the further analysis of the dynamics of the Revolute clearance Joint in a mechanical system. This allows for predicting the influence of design parameter changes, in order to minimize contact forces, accelerations, and power requirements due to the existence of Joint clearance.
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the effect of the lubricated Revolute Joint parameters and hydrodynamic force models on the dynamic response of planar multibody systems
Nonlinear Dynamics, 2012Co-Authors: Margarida F Machado, Eurico Seabra, João B. Costa, Paulo FloresAbstract:In this work a comprehensive methodology for dynamic modeling and analysis of planar multibody systems with lubricated Revolute Joints is presented. In general, this type of mechanical systems includes journal-bearings in which the load varies in both magnitude and direction. The fundamental issues associated with the theory of lubrication for dynamically loaded journal-bearings are revisited that allow for the evaluation of the Reynolds equation for dynamic regime. This approach permits the derivation of the suitable hydrodynamic force laws that are embedded into the dynamics of multibody systems formulation. In this work, three different hydrodynamic force models are considered, namely the Pinkus and Sternlicht approach for long journal-bearings and the Frene et al. models for both long and short journal-bearings. Results for a planar slider–crank mechanism with a lubricated Revolute Joint between the connecting-rod and slider are presented and utilized to discuss the assumptions and procedures adopted throughout the present study. Different test scenarios are taken into account with the purpose of performing a comparative study for quantifying the effect of the clearance size, lubricant viscosity, input crank speed and hydrodynamic force model on the dynamic response of multibody systems with lubricated Revolute Joints. From the global results obtained from computational simulations, it can be concluded that the clearance size, the lubricant viscosity and the operating conditions play a key role in predicting the dynamic behavior of multibody systems.
Qing Wang - One of the best experts on this subject based on the ideXlab platform.
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Chaotic characteristic analysis of spatial parallel mechanism with clearance in spherical Joint
Nonlinear Dynamics, 2018Co-Authors: Wenhua Gao, Qing WangAbstract:The spherical Joint is one of the main motion pairs in spatial parallel mechanism, and the spherical clearance has a great effect on the nonlinear dynamic performance of parallel mechanism. Most previous studies mainly focused on planar mechanism with Revolute Joint, spatial parallel mechanism with spherical clearance researched rarely. In this paper, the chaotic characteristic analysis of spatial 4-UPS (universal Joint-prismatic pair-spherical Joint)-RPU (Revolute Joint-prismatic pair-universal Joint) parallel mechanism with spherical clearance is investigated. The models of spherical Joint with clearance are established, and then the nonlinear dynamics equation of the parallel mechanism with spherical clearance is derived by Lagrange method. The influence of clearance on displacement, velocity and acceleration of moving platform is both analyzed. And the influence of different clearance sizes on contact force and center trajectory of the spherical clearance is analyzed, and the chaotic characteristics of spherical Joint and the mechanism are all studied by phase diagram, Poincare section mapping method and Lyapunov exponent. The results show that spherical clearance has great influence on the nonlinear dynamic performance of 4-UPS-RPU parallel mechanism, and chaos exists in the dynamic response of spherical clearance and the mechanism. As the clearance value increases, the stability of the mechanism is weakened. When the clearance value increases to 2.1 mm, chaotic motion appeared on the moving platform of the mechanism. This research is a useful attempt to study the nonlinear dynamics characteristic of parallel mechanisms with spherical clearance, which has guiding significance and practical value for further research on the design and chaotic control of parallel mechanism.
Yang Zhao - One of the best experts on this subject based on the ideXlab platform.
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A hybrid contact force model of Revolute Joint with clearance for planar mechanical systems
International Journal of Non-Linear Mechanics, 2013Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract The contact force model during the contact process of Revolute Joints with clearance is one of the most important contents. This paper presents a new contact force model of Revolute Joint with clearance for planar mechanical systems, which is a hybrid model of the Lankarani–Nikravesh model and the improved elastic foundation model. The framework of the Lankarani–Nikravesh model is used with the nonlinear stiffness coefficient derived using the improved elastic foundation model and the damping applied in introducing the ratio of the nonlinear stiffness coefficient of the improved elastic foundation model and contact stiffness of Lankarani–Nikravesh model. Furthermore, the hybrid contact force model is analyzed and compared with Lankarani–Nikravesh model as well as other existing contact models. The tangential contact is represented by using modified Coulomb friction model. And then, the dynamic characteristics of mechanical system with Revolute clearance Joint are analyzed based on the hybrid contact force model. The correctness and validity of the hybrid contact force model of the Revolute Joint clearance is verified through the demonstrative application example. Finally, the numerical simulation results show that the presented hybrid contact force model is an effective and new method to predict the dynamic characteristics of planar mechanical systems with clearance in Revolute Joints.
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dynamics modeling and quantitative analysis of multibody systems including Revolute clearance Joint
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2012Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract The dynamics characteristics of multibody mechanical systems including Revolute Joints with clearance are investigated using a computational methodology and a quantitative analysis method is proposed in this work. The contact force model in Revolute Joint clearance is performed using a nonlinear continuous contact force model and the friction effect is considered using a modified Coulomb friction model. The planar four-bar mechanism is used as demonstrative application example to validate the quantitative analysis method. Numerical results for four-bar mechanism with Revolute clearance Joint are presented and discussed. Further, two kinds of dimensionless indicator are defined for quantitative analysis of mechanical system with Joint clearance. And the clearance size, friction effects and crank driving speed are analyzed separately.
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dynamic behaviour analysis of planar mechanical systems with clearance in Revolute Joints using a new hybrid contact force model
International Journal of Mechanical Sciences, 2012Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract In this study, the dynamic behaviour of planar mechanical systems including Revolute Joints with clearance is investigated using a computational methodology. The contact model in Revolute Joint clearance is established using a new nonlinear continuous contact force model, which is a hybrid contact force model, and the friction effect is considered using modified Coulomb friction model. And then, the dynamic characteristics of planar mechanical system with Revolute Joint clearance are analysed based on the new contact model. Numerical results for two simple planar mechanisms with Revolute clearance Joints are presented and discussed. The correctness and validity of the new contact force model of Revolute Joint clearance is verified through the demonstrative application examples. Clearance size and friction effect are analysed separately. The numerical simulation results show that the proposed contact force model is a new method to predict the dynamic behaviour of planar mechanical system with clearance in Revolute Joints.
Wenhua Gao - One of the best experts on this subject based on the ideXlab platform.
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Chaotic characteristic analysis of spatial parallel mechanism with clearance in spherical Joint
Nonlinear Dynamics, 2018Co-Authors: Wenhua Gao, Qing WangAbstract:The spherical Joint is one of the main motion pairs in spatial parallel mechanism, and the spherical clearance has a great effect on the nonlinear dynamic performance of parallel mechanism. Most previous studies mainly focused on planar mechanism with Revolute Joint, spatial parallel mechanism with spherical clearance researched rarely. In this paper, the chaotic characteristic analysis of spatial 4-UPS (universal Joint-prismatic pair-spherical Joint)-RPU (Revolute Joint-prismatic pair-universal Joint) parallel mechanism with spherical clearance is investigated. The models of spherical Joint with clearance are established, and then the nonlinear dynamics equation of the parallel mechanism with spherical clearance is derived by Lagrange method. The influence of clearance on displacement, velocity and acceleration of moving platform is both analyzed. And the influence of different clearance sizes on contact force and center trajectory of the spherical clearance is analyzed, and the chaotic characteristics of spherical Joint and the mechanism are all studied by phase diagram, Poincare section mapping method and Lyapunov exponent. The results show that spherical clearance has great influence on the nonlinear dynamic performance of 4-UPS-RPU parallel mechanism, and chaos exists in the dynamic response of spherical clearance and the mechanism. As the clearance value increases, the stability of the mechanism is weakened. When the clearance value increases to 2.1 mm, chaotic motion appeared on the moving platform of the mechanism. This research is a useful attempt to study the nonlinear dynamics characteristic of parallel mechanisms with spherical clearance, which has guiding significance and practical value for further research on the design and chaotic control of parallel mechanism.
Zheng Feng Bai - One of the best experts on this subject based on the ideXlab platform.
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a study on dynamic characteristics of satellite antenna system considering 3d Revolute clearance Joint
International Journal of Aerospace Engineering, 2020Co-Authors: Zheng Feng Bai, Jijun ZhaoAbstract:Clearances in the Joints of real mechanisms are unavoidable due to assemblage, manufacturing errors, and wear. The dual-axis driving and positioning mechanism is one kind of space actuating mechanism for satellite antenna to implement precise guidance and positioning. However, in dynamics analysis and control of the satellite antenna system, it is usually assumed that the Revolute Joint in the satellite antenna system is perfect without clearances or imperfect with planar radial clearance. However, the axial clearance in an imperfect Revolute Joint is always ignored. In this work, the Revolute Joint is considered as a 3D spatial clearance Joint with both the radial and axial clearances. A methodology for modeling the 3D Revolute Joint with clearances and its application in satellite antenna system is presented. The dynamics modeling and analysis of the satellite antenna system are investigated considering the 3D Revolute clearance Joint. Firstly, the mathematical model of the 3D Revolute clearance Joint is established, and the definitions of the radial and axial clearance are presented. Then, the potential contact modes, contact conditions, and contact detection of the 3D Revolute clearance Joint are analyzed. Further, the normal and tangential contact force models are established to describe the contact phenomenon and determine the contact forces in the 3D Revolute clearance Joint. Finally, a satellite antenna system considering the 3D Revolute clearance Joint with spatial motion is presented as the application example. Different case studies are presented to discuss the effects of the 3D Revolute clearance Joint. The results indicate that the 3D Revolute clearance Joint will lead to more severe effects on the dynamic characteristics of the satellite antenna system. Therefore, the effects of axial clearance on the satellite antenna system cannot be ignored in dynamics analysis and design of the satellite antenna system.
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A hybrid contact force model of Revolute Joint with clearance for planar mechanical systems
International Journal of Non-Linear Mechanics, 2013Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract The contact force model during the contact process of Revolute Joints with clearance is one of the most important contents. This paper presents a new contact force model of Revolute Joint with clearance for planar mechanical systems, which is a hybrid model of the Lankarani–Nikravesh model and the improved elastic foundation model. The framework of the Lankarani–Nikravesh model is used with the nonlinear stiffness coefficient derived using the improved elastic foundation model and the damping applied in introducing the ratio of the nonlinear stiffness coefficient of the improved elastic foundation model and contact stiffness of Lankarani–Nikravesh model. Furthermore, the hybrid contact force model is analyzed and compared with Lankarani–Nikravesh model as well as other existing contact models. The tangential contact is represented by using modified Coulomb friction model. And then, the dynamic characteristics of mechanical system with Revolute clearance Joint are analyzed based on the hybrid contact force model. The correctness and validity of the hybrid contact force model of the Revolute Joint clearance is verified through the demonstrative application example. Finally, the numerical simulation results show that the presented hybrid contact force model is an effective and new method to predict the dynamic characteristics of planar mechanical systems with clearance in Revolute Joints.
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dynamics modeling and quantitative analysis of multibody systems including Revolute clearance Joint
Precision Engineering-journal of The International Societies for Precision Engineering and Nanotechnology, 2012Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract The dynamics characteristics of multibody mechanical systems including Revolute Joints with clearance are investigated using a computational methodology and a quantitative analysis method is proposed in this work. The contact force model in Revolute Joint clearance is performed using a nonlinear continuous contact force model and the friction effect is considered using a modified Coulomb friction model. The planar four-bar mechanism is used as demonstrative application example to validate the quantitative analysis method. Numerical results for four-bar mechanism with Revolute clearance Joint are presented and discussed. Further, two kinds of dimensionless indicator are defined for quantitative analysis of mechanical system with Joint clearance. And the clearance size, friction effects and crank driving speed are analyzed separately.
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dynamic behaviour analysis of planar mechanical systems with clearance in Revolute Joints using a new hybrid contact force model
International Journal of Mechanical Sciences, 2012Co-Authors: Zheng Feng Bai, Yang ZhaoAbstract:Abstract In this study, the dynamic behaviour of planar mechanical systems including Revolute Joints with clearance is investigated using a computational methodology. The contact model in Revolute Joint clearance is established using a new nonlinear continuous contact force model, which is a hybrid contact force model, and the friction effect is considered using modified Coulomb friction model. And then, the dynamic characteristics of planar mechanical system with Revolute Joint clearance are analysed based on the new contact model. Numerical results for two simple planar mechanisms with Revolute clearance Joints are presented and discussed. The correctness and validity of the new contact force model of Revolute Joint clearance is verified through the demonstrative application examples. Clearance size and friction effect are analysed separately. The numerical simulation results show that the proposed contact force model is a new method to predict the dynamic behaviour of planar mechanical system with clearance in Revolute Joints.
