检索结果-内蒙古大学图书馆

Research Square 2020年

作者： Duan, Yong-Chuan Zhang, Fang-Fang Liu, Yu Qiao, Hai-Di Yang, Liu Guan, Ying-Ping Key Laboratory of Advanced Forming & Stamping Technology and Science Ministry of Education of China Yanshan University Qinhuangdao Hebei066004 China College of Mechanical Engineering Yanshan University Qinhuangdao Hebei066004 China

Forming of various customized bending parts, small batches, as well as numerous types of materials is a new challenges for Industry 4.0, the current control strategies can not meet the precision and flexibility requirement, expected control strategy of bending processes need to not only resist unknown interferences of process condition and models, but also produce various new parts automatically and efficiently. In this paper, a precision and flexible bending control strategy based on analytical models and data models is proposed to built adaptive bending systems. New analytical prediction models for loading and unloading are established and suitable for various materials, a sequential identification strategy is proposed to search nominal properties using the four sub-optimization models. A data-based feedback model is established to prevent over-bending and eliminate online deviation. Above models are merged into a precision and flexible control strategy. the system firstly uses sub-optimization models to search the nominal point which is near to target point, secondly the system further uses feedback model to eliminate residual error between the nominal point and target point. Compared with four kinds sheet metals, the allowable ranges for variables are determined for a good convergence. The target bending angles were set to 20°, 40°, and 60°. Forty parts were tracked for each kind material, the adaptive bending system converged after one iteration, and exhibited better performances. © 2020, CC BY.

关键词： Analytical models

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Structural optimization and performance research on the piston pair of low speed high torque water hydraulic motor

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Meitan Xuebao/Journal of the China Coal Society 2013年第SUPPL.2期38卷 536-542页

作者： Wang, Zhi-Qiang Gao, Dian-Rong Huang, Yao Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Qinhuangdao 066004 China Key Laboratory of Advanced Forging and Stamping Technology and Science Ministry of Education of China Yanshan University Qinhuangdao 066004 China

The aim of this paper was to find an optimal configuration to improve the static and dynamic characteristics of the piston pair. Based on the equilibrium equation and the flow equation, the mathematical models of the power loss and the dynamic characteristics were established. The total power loss, the velocity and the displacement of roll ball can be the performance indexes of the piston pair. Different size of the water film thickness has different performance indexes. So the influence of the water film thickness on the piston pair was analyzed in detail. An optimal model, with the minimum of the total power loss of the piston pair as optimization objective, was established, which refers to the hydrostatic bearing characteristics of piston pair. The parameters of piston pair were obtained by optimum design. When θ0 is 19°, the diameter of piston tail is 15 mm and the diameter of damper orifice is 0.18 mm, the optimum water film thickness of piston pair is 2.027 μm. The research shows that optimized piston pair has lower power loss, good lubricating performance, and higher static and dynamic performance.

关键词： Pistons

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Research on the Relationship between Classic Denavit-Hartenberg and Modified Denavit-Hartenberg

Research on the Relationship between Classic Denavit-Hartenb...

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International Symposium on Computational Intelligence and Design, ISCID

作者： Hang Wang Hanghang Qi Minghui Xu Yanhua Tang Jiantao Yao Xuedong Yan Ming Li Shanghai University Haitian Plastics Machinery Ltd. Ningbo HAITIAN Drive Systems Co. Ltd. Yanshan University Parallel Robot and Mechatronic System Laboratory of Hebei Province Key Laboratory of Advanced Forging & Stamping Technology and Science Yanshan University Department of Chemistry Northeast Normal University NINGBO VEKEN BATTERY CO. LTD

ISBN: (纸本)9781479970063

Currently, homogeneous transformation method has been widely used for its advantages in robot. Its more commonly used modeling methods are classic Denavit-Hartenberg method and modified Denavit-Hartenberg method, but the relationship between the two is very few devoted. Then, the use area is limited. Therefore, the relationship between classic Denavit-Hartenberg method and modified Denavit-Hartenberg method for robotics research has important practical significance. Based on this, the geometric representations of classic Denavit-Hartenberg method and modified Denavit-Hartenberg method are described respectively, the models of link parameters are built by the two, and the corresponding transformation matrix is deduced. The relationship between classic Denavit-Hartenberg method and modified Denavit-Hartenberg method is researched deeply, and the relational expression of classic Denavit-Hartenberg method and modified Denavit-Hartenberg method is obtained. The research results of this paper are useful for the robot kinematics, dynamics and control algorithms.

关键词： Joints Kinematics Heuristic algorithms Service robots Robot kinematics Mechatronics

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Microstructure, Tensile Properties and Heat-Resistant Properties of Selective Laser Melted Almgsczr Alloy Under Long-Term Aging Treatment

SSRN

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SSRN 2022年

作者： Bi, Jiang Liu, Lei Chen, Guang Jia, Xiangdong Chen, Xi Xia, Hongbo Li, Xiaopeng Starostenkov, Mikhail Dmitrievich Han, Bing Dong, Guojiang Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Qinhuangdao066004 China College of Mechanical and Electrical Engineering Nanjing Forestry University Nanjing210037 China State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Harbin150001 China School of Mechanical Engineering Yangzhou University Yangzhou225127 China College of Material Science and Engineering Nanjing University of Science and Technology Nanjing210094 China General Physics Department Altai State Technical University Leninst. 46 Barnaul656099 Russia Institute of Intelligent Manufacturing Guangdong Academy of Sciences Guangdong Key Laboratory of Modern Control Technology Guangzhou510070 China

Selective laser melting (SLM)-processed AlMgScZr alloy has aroused widespread interest in the aerospace industry due to its outstanding comprehensive performance and excellent heat resistant properties. The fine grain morphology and diffusely distributed thermally stable precipitates of this alloy are believed to play a critical role in its high-temperature performance. By modifying the alloy with Sc and Zr, nano-sized Al3(Sc, Zr) phases can act as heterogeneous nucleating particles to effectively promote grain refining and precipitate strengthening. In this paper, a Sc and Zr-modified Al-Mg alloy was printed by SLM, and the long-term aging treatments in the temperature range of 275-350 ℃ with a constant holding time of 144 h were performed to investigate the heat-resistant properties of this alloy. Under as-fabricated condition, the AlMgScZr alloy exhibited high tensile strengths of 487.7 MPa and 393.9 MPa at temperatures of 25 ℃ and 200 ℃, respectively. When the alloy was aged at 300 ℃ for 144 h, its grain morphology was almost unchanged, but its tensile strength and elongation at room temperature reached 501.3 MPa and 31.3 %, respectively. This SLM-fabricated AlMgScZr alloy is expected to replace some titanium alloy components for medium-temperature applications. © 2022, The Authors. All rights reserved.

关键词： Aluminum alloys

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Deployable unit 3R-3URU and its application in deployable truss antenna

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Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2017年第11期38卷 421285页

作者： Liu, Wenlan Xu, Yundou Yao, Jiantao Chen, Liangliang Wang, Hui Zhao, Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education Yanshan University Qinhuangdao066004 China Xi'an710100 China

A spatial deployable unit 3R-3URU with one Degree of Freedom (DoF) is proposed. The DoF of the single closed-loop mechanism RURUR is analyzed, based on the screw theory and the modified G-K formula. The analytical expression for the velocities of active joints and passive joints of the mechanism RURUR are then established. According to the velocity expression and the structural characteristic that three RURUR mechanisms share their first and last revolute joints, the DoF of the 3R-3URU mechanism is derived. The geometrical relationship among the positions and directions of all joints is also obtained when the 3R-3URU mechanism has one DoF. Novel deployable mechanisms are obtained by applying the 3R-3URU mechanism to the 3RR-3RRR tetrahedral unit and a deployable truss antenna composed of the tetrahedral units, and the novel mechanisms have two types of DoFs: movement and orientation adjustment. DoF analysis and application of the 3R-3URU deployable unit are verified by the Adams software. The proposed deployable unit 3R-3URU has the advantages of one DoF, simple structure, and single type of joints, and can be applied to the supporting mechanism of deployable truss antennas with a curved surface to achieve a large folding ratio. © 2017, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Degrees of freedom (mechanics)

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Functional microstructural surface manufacturing and assessment

Functional microstructural surface manufacturing and assessm...

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第五届国际仿生工程学术大会(ICBE2016)

作者： Xun Chen James Wharton Zhiqing Hu Chengchun Zhang Haolin Li Haoyang Cao Advanced Manufacturing Technology Research Laboratory General Engineering Research InstituteLiverpool John Moores Unisity Rolling Forging Research Institute Jilin University Key Laboratory of Engineering Bionics (Ministry of Education) Jilin University College of Mechanical Engineering University of Shanghai for Science and Technology

Reduction of energy consumption is one of key issues for the sustainable development. Recent technological development in manufacturing technology has enabled engineers to create surfaces with defined geometrical structures. This paper will presents a review of the currently available literature surrounding the research of functional structural surfaces in relation to the beneficial properties, such as frictional reduction and drag reduction. Various manufacturing methods for the creation of microstructural surface will be compared in terms of production efficiency and economic production scale. A particular focus will be put on grinding which provides a new way for structural functional surface creation. Many researchers have attempted to relate the measured parameters of micro-structured surfaces to different functions. The paper will present some research results on the metrological parameters, which are currently used in industry. The investigation results show that the commonly used surface roughness measure, for example, Ra, may not be the best parameter for the functional surface quality control in terms of tribological performance. With the investigation conducted, it would suggest that 3D measurement parameters could be better that those 2D parameters. It was found that some particular structures on functional surface possess beneficial functions that could reduce energy consumption. Some recent investigations in LJMU will also be introduced to demonstrate the benefits could be acquired from microstructural surfaces.

关键词： microstructural surface manufacture assessment

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Structure Parameters and Displacement Equations of Goldberg Mechanisms With the Rank More Than sixStructure Parameters and Displacement Equations of Goldberg Mechanisms With the Rank More Than Six

Research Square

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Research Square 2020年

作者： Zhang, Yitong Lu, Ling Liu, Wenlan Li, Yanwen Hu, Bo Mu, Dejun Lu, Wenjuan Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of National Education Yanshan University Qinhuangdao066004 China Heavy-duty Intelligent Manufacturing Equipment Innovation Center of Hebei Province Yanshan University Qinhuangdao066004 China College of Energy and Power Engineering Lanzhou University of Technology Lanzhou730050 China

An infinite number of N-bar Goldberg mechanisms with the rank more than six are proposed. A single closed-loop eight-bar mechanism is first developed by removing the common side links of adjacent loops from the five-loop Bennett mechanism in which all loop frames are collinear. An analysis of trajectory circles of the links shows that the mechanism developed maintains the original constraint conditions and kinematic characteristics, and that its degree of freedom (DOF) is also one. This novel single-loop mechanism is named the eight-bar Goldberg mechanism because of its similar constraint characteristics with the five-bar and six-bar Goldberg mechanisms. The eight displacement parameters of this mechanism are analyzed by using the interior angles of adjacent links, and the five cosine equations for the tangent product of the stagger angles between adjacent links are established in together with one angular displacement equation of odd links and one angular displacement equation of even links. This novel mechanism has one DOF, eight displacement parameters and seven independent displacement equations. The loop rank of the eight-bar Goldberg mechanism is seven, which revises the existing mechanism theory of single closed-loop mechanisms with the rank no more than six. Similarly, a nine-bar Goldberg mechanism is constructed, and its nine displacement parameters are analyzed. This mechanism has eight independent displacement equations and the loop rank is eight, proving that the mechanisms with the rank more than six are not rare. Then, according to the characteristics of the independent displacement equations of the eight-bar and nine-bar Goldberg mechanisms, the N (N>7) displacement parameters of N-bar Goldberg mechanisms are analyzed, and the (N–1) independent displacement equations are deduced with odd and even Ns. It is proved that the loop rank of N-bar Goldberg mechanisms is (N–1), so there exist an infinite number of mechanisms with the rank more than six. © 202

关键词： Degrees of freedom (mechanics)

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The High Magnetic-Field-Induced Thermodynamic Mechnism in the Interface between the Carbides and Martrix in Steel

SSRN

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SSRN 2024年

作者： Zheng, Yihang Hou, Tingping Cheng, Shi Yang, Yuhao Zhang, Dong Zeng, Wenfeng Xiong, Wu Wu, Kaiming The State Key Laboratory of Refractories and Metallurgy Joint International Research Laboratory of Refractories and Metallurgy Hubei Province Key Laboratory of Systems Science on Metallurgical Processing International Research Institute for Steel Technology Collaborative Center on Advanced Steels Wuhan University of Science and Technology Wuhan430081 China Wuhan Heavy Industry Casting and Forging Co. Ltd Wuhan430081 China

The physical mechanism of the magnetic field-induced phase transition for M23C6/α-Fe was investigated utilizing a combination of high-resolution transmission electron microscopy (HRTEM) with Micromagnetic theory. The HRTEM results revealed that the M23C6/α-Fe interface exhibited a specific magnetic field-induced phase transition under the action of a high-temperature magnetic field, which increased the interface thickness between the carbide and matrix. Micromagnetic modeling establishes the relationship between the boundary thickness and the external magnetic field. The magnetization curves of carbide and matrix under high magnetic field are significantly shifted toward high temperature, which contributes to the reduction of the magnetic structure difference between M23C6 and α-Fe. The application of a strong magnetic field has a notable effect on the magnetization curve, shifting it towards higher temperatures. This diminishes the discrepancy in magnetic structure between M23C6 and α-Fe, leading to a substantial reduction in magnetostatic energy while concurrently augmenting magnetic exchange energy. Consequently, this process results in an increased thickness of the boundary between M23C6 and α-Fe. Combination of experiment and theory verifies the physical mechanism of the phase transition of carbides by magnetic field to provide a new theoretical basis for the formation of carbides by magnetic field. © 2024, The Authors. All rights reserved.

关键词： Carbides

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Mobility analysis of a deployable truss-antenna mechanism-Method based on link-demolishing and equivalent idea

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Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2017年第9期38卷 421188-1-421188-1-421188-12页

作者： Xu, Yundou Liu, Wenlan Chen, Liangliang Yao, Jiantao Zhao, Yongsheng Zhu, Jialong Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University Qinhuangdao066004 China Xi'an710100 China

A method for Degree Of Freedom (DOF) analysis of spatial mechanisms with multiple coupled-loops is proposed based on the link-demolishing and equivalent idea, in view of the multi-loop coupling characteristic of a deployable truss antenna assembled by tetrahedral elements. The coupling constraint chain of the deployable tetrahedral element is removed, and the remainder is regarded as a parallel mechanism. The number and characteristic of the DOF of each output node are then analyzed using the screw theory, and the equivalent serial kinematic chain between the output nodes and the fixed node are then established. The equivalent mechanism of the deployable tetrahedral element is obtained by reconstructing the coupling constrained chain. The number and characteristic of the DOF of the equivalent mechanism are got using the modified G-K formula and the reciprocal screw theory, respectively. As a result, the kinematic characteristics of the tetrahedral element are known. The structure of the minimum composite unit and the large-scale truss deployable antenna are simplified, according to the equivalent mechanism and the combination of the tetrahedral elements. The numbers of the DOF of the minimum composite unit and the large-scale truss deployable antenna are derived on the basis of the geometric constraint equations. The simulation model for a deployable truss antenna assembled by 27 tetrahedral elements is built, and its DOF is verified. The result shows that the DOF of the antenna analyzed by the proposed method is correct. The method lays a foundation for further analysis of the kinematics and dynamics of similar type of antennas, providing a new idea for DOF analysis of other multi-loop coupling mechanisms. © 2017, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Antennas

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Deployable antenna mechanism with class of modular truss based on tetrahedral combination unit

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Hangkong Xuebao/Acta Aeronautica et Astronautica Sinica 2020年第3期41卷 423219页

作者： Guo, Jinwei Huang, Zhirong Xu, Yundou Guo, Luyao Yao, Jiantao Zhao, Yongsheng Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao066004 China Xi'an710100 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University Qinhuangdao066004 China

To solve the complex structure, the low folding rate, and the large number of motion pairs of the existing tetrahedral-based truss antenna mechanism, a class of new modular deployable structure is proposed based on the 3RR-3RRR tetrahedral combination unit and the 3RR-3URU tetrahedral symmetric combination unit. The modular structure consisting of three combination units is selected as the analysis object. First, the composition of the modular structure and the axis arrangement of the Hook hinges are introduced in detail, and the number and property of the Degree of Freedom (DOF) of the combination unit itself are obtained by applying the idea of link-demolishing-equivalent-restoration, the screw theory and the G-K formula. Second, the motion simulation of the two modular structures is carried out by using Adams dynamics simulation software. The simulation results verified the correctness of the DOF analysis. The folding rate of the mechanism is characterized by the ratio of the space volume occupied by the mechanism when fully unfolding and fully folding. The folding rates of the existing non-modular mechanisms and modular mechanisms based on tetrahedral unit are calculated. Finally, the number of DOF and motion pairs, the folding rate of non-modular mechanisms and modular mechanisms are compared and analyzed. The analysis results show that the modular structure based on the 3RR-3URU tetrahedral symmetrical combination unit can achieve a large folding rate, and the number of degree of freedom and motion pairs are also relatively reduced. In addition, fewer types of links are use when forming large antennas. The research results provide a theoretical basis for the design and analysis of such modular truss deployable antenna structures. © 2020, Press of Chinese Journal of Aeronautics. All right reserved.

关键词： Trusses

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