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design and kinematic analysis of a novel over constrained parallel manipulator

Paper Asia 2018年第Compendium3期2018卷 87-93页

作者： Zhang, Chao Li, Bin Guo, Peng Zhao, Xinhua Yang, Yuwei Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education [Tianjin University of Technology United States

In this paper, a novel over constrained 2-RRU&RSR parallel manipulator is proposed and analysed. This mechanism is composed of a moving platform and a base, which connected by two identical RRU limbs and one RSR limb. Here, R stand for the revolute, U and S represent universal and spherical joints respectively. Three revolute joints, fixed on the base, are set to be actively actuated. The moving platform of the structure can realize two rotational and one translational freedoms. The design process and kinematic performances are studied in this paper. Firstly, the configuration design and structure characteristics of the mechanism are expounded. Secondly, the number and the properties of degrees of freedom (DOF) of the mechanism are analysed using screw theory. Thirdly, the kinematic problems, including the inverse analyses and the forward position analyses, are solved analytically. Then, the performance of the mechanism, such as reachable workspace, transmission capability, are analysed. Finally, some numerical examples and conclusions of the mechanism are pointed out, and the potential applications of the mechanism are suggested.

关键词： Degrees of freedom (mechanics)

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Study on design method for dynamics of machine tools based on advanced process system

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Paper Asia 2018年第4期COMPENDIUM VOL. 1卷 102-105页

作者： Zhu, Peihao Li, Xiang Lu, KaiJie Zheng, QingChun Liu, JingNa Ma, WenPeng Hu, YaHui Yu, YangBin Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin300384 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300384 China

Machining accuracy depends not only the manufacturing error, thermal deformation, elastic deformation and wear but also the vibration produced by it. Establishing the dynamics model provides the basis of dynamic analysis. The most common dynamic models of machine tool are finite element model, lumped parameter model, distributed mass model and parameters identification. Above methods are applied by using the methods of multi-body dynamics, finite element and the progress of technology. design is finite optimization based on dynamic analysis to get limited improvements for existing empirical design. It is not possible to design the machine tool as required to achieve the expected dynamic performance. In order to comply with precision machine tool’s development demand and the challenge of machine structure design, This paper presents physical and dynamic models considering Machine-Tool-Workpiece Process system to discusses the dynamic cutting process of the dynamic cutting load, driving and executing devices under the excitations of non-equilibrium inertial load. The dynamic of machine tool is mapped to the relative displacement of tool nose. © 2018, SHPMedia Sdn Bhd. All rights reserved.

关键词： Dynamic models

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Flow Mechanism of Cooling Effectiveness Improvement for the Cylindrical Film Cooling Hole with Contoured Craters

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IOP Conference Series: Materials Science and Engineering 2019年第1期473卷

作者： Linchao Bai Chao Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control 300384 Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin 300384 China

In this paper, a typical cylindrical hole with contoured craters is investigated in terms of the downstream flow field by numerical method at blowing ratios of 0.5, 1 and 1.5. The flow field and the cooling effectiveness are analyzed using three-dimensional Reynolds-averaged Navier-Stokes equations with the shear stress transport turbulence model. In comparison to the cylindrical hole, the cratered hole shows a wider coolant coverage in lateral direction and a lower penetration into the mainstream flow due to the larger hole exit area. Moreover, the interaction between the coolant and the curved protrusion induces a new anti-kidney-shaped vortex pair, which can obviously improve the cooling coverage and thus the cooling effectiveness. The area-averaged cooling effectiveness for the cratered hole is always higher than that for the cylindrical hole at all three blowing ratios.

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Comparison on Thermodynamic Performances between Basic and Regenerative Sub-Critical Organic Rankine Cycles Coupled with Low Grade Heat Source

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IOP Conference Series: Materials Science and Engineering 2019年第1期473卷

作者： Pengfei Yuan Chao Zhang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control 300384 Tianjin China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education (Tianjin University of Technology) Tianjin 300384 China

The coupling effects of low grade heat source on thermodynamic performances of both the basic and regenerative sub-critical Organic Rankine cycle (ORC) systems are investigated and compared. Turbine inlet pressure and turbine inlet temperature are treated as independent variables. The system exergy efficiency is selected as the thermodynamic performance criterion. The waste hot water with temperature range of 373.15K to 423.15K is selected as the low grade heat source. Optimization studies are carried out by using eight common organic working fluids to recover heat energy, and relevant operating conditions are obtained respectively. The results indicate that both hot fluid inlet temperature and the allowable minimum hot fluid outlet temperature influence the optimal working fluid, relevant turbine inlet condition and system exergy efficiency. Optimal system exergy efficiency increases monotonously with increasing of hot fluid temperature for both ORC systems above. In comparison to the basic cycle configuration, optimal system exergy efficiency for the regenerative system using the same working fluid is not changed if relevant turbine inlet vapor is saturated, but is significantly improved if relevant turbine inlet vapor is overheating. Besides, the optimal working fluid is dependent on the heat source temperature and specific cycle configuration.

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Theoretical prediction and experimental testing of mechanical properties for 3d printed silk fibroin-type II collagen scaffolds for cartilage regeneration

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MCB Molecular and Cellular Biomechanics 2018年第2期15卷 85-98页

作者： Gao, Lilan Yuan, Qingxian Li, Ruixin Chen, Lei Zhang, Chunqiu Zhang, Xizheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin30000 China National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin300000 China Hospital of Stomatolgy NanKai University Tianjin300000 China

Silk fibroin-type II collagen scaffold was made by 3D printing technique and freeze-drying method, and its mechanical properties were studied by experiments and theoretical prediction. The results show that the three-dimensional silk fibroin-typeII collagen scaffold has good porosity and water absorption, which is (89.3%+3.26%) and (824.09%+93.05%), respectively. With the given strain value, the stress of scaffold decreases rapidly firstly and then tends to be stable during the stress relaxation. Both initial and instantaneous stresses increase with increase of applied strain value. The creep strains of scaffold with different stress levels show the two stages: the rapidly increasing stage and the second stable stage. It is noted that the scaffold with compressive stress of less than 35 kPa can recover when the compressive stress is removed. However when the compressive stress is higher than 50 kPa, the scaffold is damaged and its structure is destroyed. Not only the compressive property but tensile property of scaffold are dependent on the applied displacement rate or strain rate. Its compressive elastic modulus and tensile modulus increase with increase of strain rate or displacement rate. The nonlinear relaxation model and creep model were constructed respectively and applied to predict the stress relaxation behavior and creep behavior of scaffold. It is found that there are good agreements between the experimental data and predictions, which mean that the built theoretical model can predict the mechanical behavior of scaffold. Copyright © 2018 Tech Science Press.

关键词： Strain rate

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Influence of Micro-texture Parameters on Bone Drilling Force and Torque: A Finite Element Model

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IOP Conference Series: Materials Science and Engineering 2019年第1期470卷

作者： Yahui Hu Xiangjun Li Chuncheng Chen Lili Su Qingchun Zheng Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China Tianjin University of Technology 391 Binshui West Road Xiqing District Tianjin 300384 China.

The micro-texture on the tool surface is an effective way to improve the quality of the drilling. While high-performance micro-texture plays an important role in improving the quality of working surface and prolonging the life of tool. In this study, a three-dimensional finite element model was established to study the relationship between drilling thrust, torque and microstructure parameters (micro-pit depth, micro-pit diameter and micro-pit spacing) during drilling of cortical bone. The model was validated by cortical bone drilling using a micro-structured tool. On basis of this, the thrust and torque prediction models of the micro-texture parameters were obtained. The results indicate that the thrust and torque increased with the increase of micro-pit diameter; while the increase of the micro-pit spacing caused the thrust and torque to decrease. When the depth of the micro-pit increased, the thrust and torque decreased first and then increased, and we found that the effect of micro-pit spacing and micro-pit depth on force and torque is insignificant.

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Author Correction: Effects of Precipitates Evolution on Low Stress Creep Properties in P92 Heat-resistant Steel

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Scientific reports 2019年第1期9卷 9567页

作者： Hongguang Han Junjie Shen Jiaxing Xie Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China. National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China. Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering Tianjin University of Technology Tianjin 300384 China. 58920151@***. National Demonstration Center for Experimental Mechanical and Electrical Engineering Education Tianjin University of Technology Tianjin 300384 China. 58920151@***.

A correction to this article has been published and is linked from the HTML and PDF versions of this paper. The error has not been fixed in the paper.

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Dynamic Analysis of a New Type of Asymmetrical Parallel Mechanism Based on Lagrange Method

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IOP Conference Series: Materials Science and Engineering 2018年第1期428卷

作者： Quan Li Bin Li Xinhua Zhao Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control Tianjin University of Technology Tianjin 300191 China

In this article, a novel over constrained 2-RRU&RSR parallel manipulator is proposed and analyzed. This mechanism is composed of a moving platform and a base, which connected by two same configuration RRU legs and one RSR leg. The article uses the 2RRU&RSR parallel mechanism that can achieve 2R1T (two rotations and one translational motion) as the object. Based on the known kinematics forward solutions, the dynamics study was carried out. The dynamic model of the parallel mechanism was established using the Lagrange method and then it can be obtained that the dynamic inverse solution. Then ADAMS software was used to build a virtual prototype of this mechanism and the dynamics simulation was performed by using Lagrange method. Under the trend of a certain trajectory, the law of driving torque changes with time, paving the way for subsequent trajectory planning and control.

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BP-PID control Applied in Evaporator of Organic Rankine Cycle system

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Instrumentation 2017年第3期4卷 54-58页

作者： WANG Zhigang GUO Shuang Tianjin Key Laboratory for Advanced Mechatronic System Design and Intelligent Control School of Mechanical Engineering & National Demonstration Center for Experimental Mechanical and Electrical Engineering Education & Tianjin University of Technology

According to the problem that the selection of traditional PID control parameters is too complicated in evaporator of Organic Rankine Cycle system(ORC),an evaporator PID controller based on BP neural netw ork optimization is designed. Based on the control theory,the model of ORC evaporator is set up. The BP algorithm is used to control the Kp,Kiand Kdparameters of the evaporator PID controller,so that the evaporator temperature can reach the optimal state quickly and steadily. The M ATLAB softw are is used to simulate the traditional PID controller and the BP neural netw ork PID controller. The experimental results show that the Kp,Kiand Kdparameters of the BP neural netw ork PID controller are 0. 5677,0. 2970,and 0. 1353,***,the evaporator PID controller based on BP neural netw ork optimization not only satisfies the requirements of the system performance,but also has better control parameters than the traditional PID controller.

关键词： Organic Rankine Cycle PID controller Evaporator BP Neural Network

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Kinematic Modeling and Error Analysis of the Six Pole Parallel Robot

Kinematic Modeling and Error Analysis of the Six Pole Parall...

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2016 IEEE advanced Information Management,Communicates,Electronic and Automation control Conference(IMCEC 2016)

作者： ZHAO Xin-hua LUAN Qian-qian ZHAO Lei WANG Shou-jun GE Wei-min FAN Meng-ran Tianjin Key Laboratory of the Design and Intelligent Control of the Advanced Mechatronic System Tianjin University of Technology School of Mechanic Engineering

ISBN: (纸本)9781509001668

The parallel manipulator has some advantages of high accuracy,high speed and high stiffness *** makes up for the shortcomings of serial *** the parallel mechanism becomes a potential motion platform with high speed and high *** poles parallel robot improves these defects of more singularity,poor load capacity and low stiffness which exist in workspace of the classic plane five poles parallel *** and forward kinematic models are established based on the structure of the *** influence of foundation beds' location error,driving angle error and rod processing error on control accuracy is systematically *** theoretical foundation has been provided for realizing the optimal design of the robot and control in high accuracy.

关键词： high speed parallel robot kinematics error analysis

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