The Experts below are selected from a list of 6078 Experts worldwide ranked by ideXlab platform
Gengxiang Wang - One of the best experts on this subject based on the ideXlab platform.
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Dynamics investigation of spatial parallel mechanism considering rod flexibility and Spherical Joint clearance
Mechanism and Machine Theory, 2019Co-Authors: Gengxiang Wang, Liang WangAbstract:Abstract The dynamic model of 4-SPS/PS parallel mechanism with a flexible actuated rod and clearance Spherical Joint is established based on the equation of motion. Firstly, the flexible actuated rod is modeled using finite element (FE) 3D beam based on the floating frame of reference (FFR) formulation since small deformation occurs in the rod. In order to build the actual dynamic model, some rigid Joints are introduced to connect the related components in 4-SPS/PS parallel mechanism. Secondly, two different sets of reference conditions are imposed at the FE analysis stage for the 3D beam to obtain the free-free modes and fixed-fixed modes based on the normal mode approach, which circumvents the fact that the free-free modes are not suitable for some instances. Further, the dimension of the whole dynamic model is reduced by the normal mode approach as well. Besides, clearance is introduced to one of the Spherical Joints in this parallel mechanism. The normal and tangential contact forces are estimated based on the Lankarani–Nikravesh contact force model and a modified Coulomb friction model, respectively. Finally, the effects of the free-free modes and fixed-fixed modes from the flexible actuated rod on the dynamic responses of the parallel mechanism with clearance Spherical Joint are firstly discussed in this investigation. The comparative analysis between considering flexible actuated rod (FAR model), considering clearance Spherical Joint (CSJ model) and simultaneously considering flexible actuated rod and clearance Spherical Joint (FAR-CSJ model) has been carried out. The simulation results showed that a reliable and comprehensive solution requires both appropriate reference conditions, and taking the clearance Spherical Joint and the flexible moving platform into consideration.
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Dynamic Analysis of 4-SPS/CU Parallel Mechanism Considering Three-Dimensional Wear of Spherical Joint With Clearance
Journal of Tribology, 2017Co-Authors: Gengxiang Wang, Hongzhao Liu, Peisheng Deng, Kaiming Yin, Guanggang ZhangAbstract:The dynamic performance of 4-SPS/CU (Spherical Joint, prismatic Joint, cylindrical Joint, and universal Joint) parallel mechanism considering Spherical Joint with clearance is developed, and the three-dimensional (3D) wear property of the socket is based on the Archard's wear model. First, the kinematics model of Spherical Joint with clearance is established, and the updated procedure pertaining to the contact mechanics and wear state is explained via a flowchart. An improved contact force model was proposed by Flores et al. contact force model through a revised contact stiffness coefficient. The normal and tangential contact forces between ball and socket are calculated using the improved contact force model and a modified Coulomb friction model. Second, the dynamic model of the parallel mechanism considering Spherical Joint with clearance is formulated based on the multibody equations of motion. In order to obtain the 3D wear property of Spherical Joint with clearance, the contact force is decomposed into three components in the global coordinate system. The three components of sliding distance are computed based on the 3D revolute property of the parallel mechanism. Finally, the contact pressures in three different directions are calculated by the corresponding contact force and approximate contact area components for the sake of predicting the 3D wear depth of socket based on the Archard's wear model. The simulation results show that the wear depth in different directions along the socket surface is nonuniform, which affects the performance of 4-SPS/CU parallel mechanism.
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Dynamics Analysis of Spatial Multibody System With Spherical Joint Wear
Journal of Tribology, 2015Co-Authors: Gengxiang Wang, Hongzhao Liu, Peisheng DengAbstract:The influence of the Spherical Joint with clearance caused by wear on the dynamics performance of spatial multibody system is predicted based on the Archard's wear model and equations of motion of multibody systems. First, the function of contact deformation and load acting on the Spherical Joint with clearance is derived based on the improved Winkler elastic foundation model and Hertz quadratic pressure distribution assumption. On this basis, considering the influence of clearance size and wear state on the contact stiffness between Spherical Joint elements, an improved contact force model is proposed by Lankarani–Nikravesh contact force model and improved stiffness coefficient that is the slope of the function of contact deformation and load. Second, due to the complexity for that wear impacts on the surface topography of contact bodies, an approximate calculation method of contact area with respect to the clearance Spherical Joint is provided for simplifying the computational process of contact pressure in the Archard's wear model. Subsequently, the contact pressure between contact bodies is calculated by the improved contact force model and approximate contact area (ICFM–ACA), which is verified via finite element method (FEM). Moreover, the dynamics model of spatial four bar mechanism considering Spherical Joint with clearance caused by wear is formulated using equations of motion of multibody systems. Finally, the wear depth of Spherical Joint with clearance is predicted via two different kinds of contact pressure based on the Archard's wear model (one is from the ICFM–ACA and the other is from FEM), respectively. The numerical simulation results show that the improved contact force model and proposed approximate contact area are correctness and validity for predicting wear in the Spherical Joint with clearance. Simultaneously, the effect of the Spherical Joint with clearance caused by wear on the dynamics performance of spatial four bar mechanism is analyzed.
Peisheng Deng - One of the best experts on this subject based on the ideXlab platform.
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Dynamic Analysis of 4-SPS/CU Parallel Mechanism Considering Three-Dimensional Wear of Spherical Joint With Clearance
Journal of Tribology, 2017Co-Authors: Gengxiang Wang, Hongzhao Liu, Peisheng Deng, Kaiming Yin, Guanggang ZhangAbstract:The dynamic performance of 4-SPS/CU (Spherical Joint, prismatic Joint, cylindrical Joint, and universal Joint) parallel mechanism considering Spherical Joint with clearance is developed, and the three-dimensional (3D) wear property of the socket is based on the Archard's wear model. First, the kinematics model of Spherical Joint with clearance is established, and the updated procedure pertaining to the contact mechanics and wear state is explained via a flowchart. An improved contact force model was proposed by Flores et al. contact force model through a revised contact stiffness coefficient. The normal and tangential contact forces between ball and socket are calculated using the improved contact force model and a modified Coulomb friction model. Second, the dynamic model of the parallel mechanism considering Spherical Joint with clearance is formulated based on the multibody equations of motion. In order to obtain the 3D wear property of Spherical Joint with clearance, the contact force is decomposed into three components in the global coordinate system. The three components of sliding distance are computed based on the 3D revolute property of the parallel mechanism. Finally, the contact pressures in three different directions are calculated by the corresponding contact force and approximate contact area components for the sake of predicting the 3D wear depth of socket based on the Archard's wear model. The simulation results show that the wear depth in different directions along the socket surface is nonuniform, which affects the performance of 4-SPS/CU parallel mechanism.
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Dynamics Analysis of Spatial Multibody System With Spherical Joint Wear
Journal of Tribology, 2015Co-Authors: Gengxiang Wang, Hongzhao Liu, Peisheng DengAbstract:The influence of the Spherical Joint with clearance caused by wear on the dynamics performance of spatial multibody system is predicted based on the Archard's wear model and equations of motion of multibody systems. First, the function of contact deformation and load acting on the Spherical Joint with clearance is derived based on the improved Winkler elastic foundation model and Hertz quadratic pressure distribution assumption. On this basis, considering the influence of clearance size and wear state on the contact stiffness between Spherical Joint elements, an improved contact force model is proposed by Lankarani–Nikravesh contact force model and improved stiffness coefficient that is the slope of the function of contact deformation and load. Second, due to the complexity for that wear impacts on the surface topography of contact bodies, an approximate calculation method of contact area with respect to the clearance Spherical Joint is provided for simplifying the computational process of contact pressure in the Archard's wear model. Subsequently, the contact pressure between contact bodies is calculated by the improved contact force model and approximate contact area (ICFM–ACA), which is verified via finite element method (FEM). Moreover, the dynamics model of spatial four bar mechanism considering Spherical Joint with clearance caused by wear is formulated using equations of motion of multibody systems. Finally, the wear depth of Spherical Joint with clearance is predicted via two different kinds of contact pressure based on the Archard's wear model (one is from the ICFM–ACA and the other is from FEM), respectively. The numerical simulation results show that the improved contact force model and proposed approximate contact area are correctness and validity for predicting wear in the Spherical Joint with clearance. Simultaneously, the effect of the Spherical Joint with clearance caused by wear on the dynamics performance of spatial four bar mechanism is analyzed.
Fang Yang - One of the best experts on this subject based on the ideXlab platform.
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Experimental study on residual performance of welded hollow Spherical Joints subjected to axial compression after a fire
Structures, 2021Co-Authors: Bingsheng Huang, Yuefei Cao, Fang YangAbstract:Abstract To study the residual performance of the welded hollow Spherical Joint after exposure to high temperatures. A total of 12 welded hollow Spherical Joint specimens are heated to six different preselected temperatures and subsequently air-cooled and water-cooled to the ambient temperature. Axial compressive tests are thereafter performed until the Joints are damaged. The displacement characteristics, strain development, failure modes, stiffness, ductility, and load bearing capacity of specimens are investigated. The results show that the mechanical properties of Spherical Joints are considerably affected by the temperatures and cooling methods. Under the air-cooling condition, both the stiffness and compressive load of Spherical Joints decrease with an increase in the exposed temperature, and the ductility increases considerably. Under the water-cooling condition, the stiffness and ductility of Spherical Joints decrease with the increase in exposed temperature. The yield and ultimate loads decrease when the temperature is up to 500 °C and then gradually increase when the temperature exceeds 500 °C.
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Experimental Study on the Behavior of Fire Resistance of Welded Hollow Spherical Joint under Compression
KSCE Journal of Civil Engineering, 2020Co-Authors: Bingsheng Huang, Yiwei Zhang, Ranyang Zhang, Fang YangAbstract:Through the transient test on two welded hollow Spherical Joints subjected to compression under fire, the temperature distribution, displacement characteristics, failure mode and ultimate fire resistance time of the Joint under different load ratios were obtained under standard fire. The three-dimensional finite element model of welded hollow Spherical Joints was established, and the performance of the Joints subjected to compression under fire was analyzed. Compared with the test results, the correctness of finite element simulation analysis was verified. The results showed that during the heating process, the surface temperature of the sphere inside the steel pipe is the lowest. The surface temperature of the sphere is low at the intersection with the steel tube and is highest at the middle-latitude of the sphere. The surface temperature of sphere is lower than ISO-834 standard heating curve. Failure mode of axially compressed welded hollow Spherical Joints under fire is concave failure. Failure position is at the sphere connected with the steel pipe. Failure process is short. Fire resistance time of load-ratio 0.35 specimen is more than 20% longer than that of load-ratio 0.6 specimen. The critical temperature of the current fire protection code is smaller than the results of the finite element.
Xiulong Chen - One of the best experts on this subject based on the ideXlab platform.
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Effects of Spherical Clearance Joint on Dynamics of Redundant Driving Spatial Parallel Mechanism
Robotica, 2020Co-Authors: Xiulong Chen, Jingyao GuoAbstract:SUMMARY This paper proposes a dynamic modeling method of redundant drive spatial parallel mechanism, dynamics of 4-UPS-RPU redundant driving spatial parallel mechanism considering Spherical Joint clearance are analyzed. The dynamic equation of Spherical Joint clearance with Lagrange multiplier is built. The influences of single clearance and multiple clearances on dynamic responses of redundant drive spatial parallel mechanisms are analyzed under different clearance values. The results show that the dynamic characteristics of the mechanism with single clearance are basically consistent with the ideal situation, and the dynamic characteristics of the mechanism with multi-clearance are significantly different from the ideal situation.
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Dynamics Analysis of Spatial Parallel Mechanism with Irregular Spherical Joint Clearance
Shock and Vibration, 2019Co-Authors: Xiulong ChenAbstract:Clearances caused by machining accuracy and assembly requirements are regular, but they will be irregular due to the wear of the kinematic pairs. At present, there are few studies on wear of space kinematic pairs. In order to grasp the effect of irregular Spherical Joint clearance after wear on the dynamic response, a method for solving irregular clearance problems based on the Newton–Euler method is proposed, and the dynamic response of 4-UPS-UPU spatial parallel mechanism with irregular Spherical Joint clearance is investigated. The kinematic model and contact force model of the clearance of the Spherical Joint are derived. The dynamic model of the mechanism with Spherical Joint clearance is established by the Newton–Euler method. Based on the Archard model, the three-dimensional dynamic wear model for Spherical Joint with clearances is developed. The wear depth and wear position of the Spherical Joint are obtained by the numerical solution. The method of reconstructing the geometric morphology after wear is proposed based on the finite element thought. The solution of the irregular clearance problem is put forward, and the dynamic response of the mechanism after wear is also analyzed. The results show that the dynamic response curves of the mechanism fluctuate around the ideal curves whether before wear or after wear. Compared with the regular clearance before wear, the results of the irregular clearance after wear have a greater impact on acceleration and contact force, and the vibration of the acceleration and contact force curve become more intense than before. Moreover, the displacement, velocity, and acceleration curves of the irregular clearance show some hysteresis than that before wear. Therefore, it can be inferred that the irregular clearance has more adverse effects on the mechanism and aggravates the wear between the elements of the kinematic Joint; in addition, the stability and the reliability of the mechanism can be reduced.
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Dynamic modeling of spatial parallel mechanism with multi-Spherical Joint clearances:
International Journal of Advanced Robotic Systems, 2019Co-Authors: Xiulong Chen, Chenghao SunAbstract:The parallel mechanism has advantages of the high speed, high precision, strong carrying capacity, and high structural rigidity. Most of the previous studies concerning the dynamic modeling focused...
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Chaotic characteristic analysis of spatial parallel mechanism with clearance in Spherical Joint
Nonlinear Dynamics, 2018Co-Authors: Xiulong Chen, Yu Deng, 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.
Weihai Chen - One of the best experts on this subject based on the ideXlab platform.
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Stiffness analysis Of 3-DOF Spherical Joint based on cable-driven humanoid arm
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Yangyi Yang, Weihai Chen, Quanzhu ChenAbstract:In this paper, the stiffness of 3-DOF (Degree of Freedom) Spherical Joint robot based on cable-driven humanoid arm is analyzed. By utilizing forward kinematics, the pose of the robot is realized. Then with the analysis of static, the torque balance relationship between cables is realized. On the basis of the analysis of pose and cable tension, the stiffness of 3-DOF Spherical Joint robot can be analyzed, which mainly includes two parts: the stiffness related to structural parameters and the stiffness related to cable tension. Finally, by utilizing software ADAMS, the numerical simulate is proposed. It concludes that: the stiffness of 3-DOF Spherical Joint robot is related to the robot pose, cable stiffness and cable tension. When the cable stiffness is low, by changing inner cable tension, it will change the stiffness of the robot. The research results will provide theoretical guidance to tension and stiffness control for robot.
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PMAC-based control system for a cable-driven Spherical Joint with angle feedback
2010 5th IEEE Conference on Industrial Electronics and Applications, 2010Co-Authors: Jianhua Wang, Suqing Liu, Weihai ChenAbstract:In this paper, a cable-driven Spherical Joint with angle feedback is proposed and the geometric numerical inverse kinematic algorithm is analyzed. Based on this, a new online control method is presented. In this method, the actual position of the Spherical Joint is calculated via inverse kinematics and the control error is compensated immediately. A experimental system with industrial PC (IPC) and PMAC motion controller is designed to demonstrate the effectiveness of the proposed algorithm and control method. Experimental results is not only effective high control precision. The control accuracy is greatly improved with real-time Joint angle feedback and on-line position error compensation.
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Structure optimization and tension analysis of a cable-driven Spherical Joint
2009 IEEE International Conference on Control and Automation, 2009Co-Authors: Quanzhu Chen, Weihai Chen, Rong Liu, Jianbin ZhangAbstract:Cable-driven Spherical Joint is a 3-DOF closed-loop mechanism which transmits motion and force of the driver on the base to the moving platform via cables. It combines the merits of cable-driven and parallel mechanism. This paper introduces a 4-cable-driven parallel structure with 3-DOF and uses a specific methodology to optimize structural parameters of the Spherical Joint. Based on the analysis above, the tension distribution of drag ropes is analyzed first. Then we give an efficient method to calculate the relationship between the pose of the platform and tension. Finally, force control strategy and algorithm of the Spherical Joint is deduced based on the tension distribution and a simulation by means of ADAMS which are carried out to verify the effectiveness of proposed algorithms.
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RAM - A novel Spherical Joint designed for metamorphic mechanism
2008 IEEE Conference on Robotics Automation and Mechatronics, 2008Co-Authors: Weihai Chen, Jianbin Zhang, Junjie QuanAbstract:A novel design of passive Spherical metamorphic Joint is proposed in this paper, the special mechanism of this design allows multi links to be connected together to do Spherical motion about a rotation center. The main contribution of the Joint design is the offset parallelogram mechanism and a couple door Joints, which can overcomes efficiently the inherent defect from the conventional Spherical Joint design where a Spherical Joint can only connect two links simultaneously to do the motion. With this novel Joint, we construct a kind of special six-bar Spherical metamorphic mechanism. It is also explained how to do the configuration analysis, and to find the adjacency matrix of the metamorphic mechanism. According to the characteristic of the Joint, some typical applications have been illustrated through parallel and variable geometry truss manipulators
