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Synchrotron X-ray tomography investigation of 3D morphology of intermetallic phases and pores and their effect on the mechanical properties of cast Al-Cu alloys

arXiv

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arXiv 2018年

作者： Zhao, Yuliang Wang, Zhi Zhang, Chun Zhang, Weiwen Guangdong Key Laboratory for Advanced Metallic Materials Processing South China University of Technology Guangzhou510641 China National Engineering Research Center of Near-net-shape Forming for Metallic Materials South China University of Technology Guangzhou510641 China School of Engineering & Computer Science University of Hull East YorkshireHU6 7RX United Kingdom School of Mechanics and Civil & Architecture Northwestern Polytechnical University Xi'an710072 China

The influence of Fe content on the three-dimensional (3D) morphology of Fe-rich intermetallic phases (Fe phases), Al2Cu, and pores and their effect on the mechanical properties of cast Al-5.0Cu-0.6Mn alloys with 0.5 and 1.0 wt. % Fe are characterized using synchrotron X-ray tomography and a tensile test. The results show that both Fe phases and Al2Cu exhibit a complex 3D network structure, and the pores are irregular with complex interconnected and near-globular shape. As the Fe content increases from 0.5 % to 1.0 %, the volume fraction and equivalent diameter of Fe phases decrease, whereas Al2Cu shows the opposite trend;however, both their interconnectivities decrease. Skeletonization analysis of four different Fe phases shows that the Chinese-script-shaped Fe phase is relatively more compact than the plate-like Fe phases. The equivalent diameter and sphericity of pores vary with Fe content, and their relationships follow exponential functions, Y = 7.14*X-1.29 and Y = 7.06*X-1.20, respectively. The addition of Fe results in a decrease in the ultimate tensile strength and elongation from 223.7 MPa to 199.8 MPa and from 5.51 % to 3.64 %, respectively, owing to more sharp-edged Fe phases and pores and less Al2Cu, resulting in stress concentration during tensile *** Codes 74AXX Copyright © 2018, The Authors. All rights reserved.

关键词： Intermetallics

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Dynamic Characteristics Analysis Of Axial Piston Pump Slipper Pair With Wear Fault

Dynamic Characteristics Analysis Of Axial Piston Pump Slippe...

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第六届工程机械与车辆工程新进展国际学术会议

作者： Zhang Geng-xin Zhang Jian-jiao Wang Chuang Liu Si-yuan Hebei Provincial Key Laboratory of Heavy Machinery Fluid Power Transmission and Control Yanshan University Key Laboratory of Advanced Forging & Stamping Technology and Science Ministry of Education of ChinaYanshan University CRRC Nanjing Puzhen Co. Ltd.

Considering development mechanism of slipper pair wear fault,the mathematical description equation of slipper wear loss and wear profile was presented,and was used to be wear correction quantity to es

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Numerical modeling of condensate droplet on superhydrophobic nanoarrays using the lattice Boltzmann method

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Chinese Physics B 2016年第6期25卷 349-354页

作者：张庆宇孙东科张友法朱鸣芳 Jiangsu Key Laboratory for Advanced Metallic Materials School of Materials Science and Engineering Southeast University Nanjing 211189 China Department of Mechanical Engineering Technology Purdue University 401 North Grant Street West Lafayette IN 47907 USA Shanghai Key Laboratory of Advanced High-Temperature Materials and Precision Forming Shanghai Jiao Tong University Shanghai 200240 China

In the present study,the process of droplet condensation on superhydrophobic nanoarrays is simulated using a multicomponent multi-phase lattice Boltzmann *** results indicate that three typical nucleation modes of condensate droplets are produced by changing the geometrical parameters of *** nucleated at the top（top-nucleation mode）,or in the upside interpillar space of nanoarrays（side-nucleation mode）,generate the non-wetting Cassie state,whereas the ones nucleated at the bottom corners between the nanoarrays（bottom-nucleation mode） present the wetting Wenzel *** evolutions of droplet pressures at the upside and downside of the liquid phase are analyzed to understand the wetting behaviors of the droplets condensed from different nucleation *** phenomena of droplet condensation on nanoarrays patterned with different hydrophilic and hydrophobic regions are simulated,indicating that the nucleation mode of condensate droplets can also be manipulated by modifying the local intrinsic wettability of nanoarray *** simulation results are compared well with the experimental observations reported in the literature.

关键词： condensate droplet superhydrophobic nanoarray wettability lattice Boltzmann method

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Stress-strain analysis on AA7075 cylindrical parts during hot granule medium pressure forming

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Journal of Central South University 2016年第11期23卷 2845-2857页

作者：董国疆杨卓云赵建培赵长财曹秒艳 College of Vehicles and Energy Yanshan University Qinhuangdao 066004 China Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of Education of China (Yanshan University) Qinhuangdao 066004 China National Engineering Research Center for Equipment and Technology of Cold Strip Rolling Yanshan University Qinhuangdao 066004 China

Hot granule medium pressure forming(HGMF) is a technology in which heat-resistant granules are used to replace liquids or gases in existing flexible-die forming technology as pressure-transfer medium. Considering the characteristic of granule medium that seals and loads easily, the technology provides a new method to realize the hot deep-drawing forming on high strength aluminum alloy sheet. Based on the pressure-transfer performance test of granule medium and the material performance test of AA7075-T6 sheet, plastic mechanics analysis is conducted for the areas, such as the flange area, force-transfer area and free deforming area, of cylindrical parts deep-drawn by HGMF technology, and the function relation of forming pressure is obtained under the condition of nonuniform distribution of internal pressure. The comparison between theoretical result and experimental data shows that larger deviation occurs in the middle and later period of forming process, and the maximum theoretical forming force is less than the experimental value by 24.6%. The variation tendency of the theoretical thickness curve is close to the practical situation, and the theoretical value basically agrees well with experimental value in the flange area and the top area of spherical cap which is in the free deforming area.

关键词： granule medium aluminum alloy sheet deep-drawing hot forming limit drawing ratio

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Frictional characteristics of granular system under high pressure

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Journal of Central South University 2016年第5期23卷 1132-1141页

作者：曹秒艳彭雅新赵长财董国疆杜冰 national engineering research center for equipment and technology of cold strip rolling(yanshan university) Qinhuangdao 066004China Key Laboratory of Advanced Forging&Stamping Technology and Science of Ministry of Education of China(Yanshan University) Qinhuangdao 066004China College of Vehicles and Energy Yanshan UniversityQinhuangdao 066004China

In order to reveal the force transmission features of the granules in the solid granule medium forming(SGMF) technology,the frictional characteristics of the non-metallic granule medium(NGM) under high pressure were investigated by tests and *** the relevant changing curves of the internal friction coefficient of the granular system under different normal pressures were obtained by self-designed shear *** the granule volume compression test,the accurate discrete element simulation parameters were obtained,based on this,the discrete element method(DEM) was adopted to reveal the evolution law of the NGM granules movement in the sample shear process from the microscopic *** on the DEM,the influence of granule diameter,surface friction coefficient,normal pressure and shear velocity on the internal friction coefficient of the granular system were *** the parameters were conducted to be dimensionless by introducing the inertia ***,the expression showing power-law relationship of inertia coefficient,surface friction coefficient and internal friction coefficient is obtained.

关键词： granule friction coefficient discrete element method inertia coefficient

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Effect of Rolling Reduction Rate on the Microstructure of Hot Rolling Stainless Steel Clad Plate

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IOP Conference Series: Materials Science and Engineering 2018年第3期394卷

作者： Herong Jin Lei Zhang Yali Yi Key Laboratory of Advanced Forging & Stamping Technology and Science of Ministry of National Education Yanshan University Qinhuangdao 066004 China Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University Qinhuangdao 066004 China School of Mechanical Engineering Yanshan University Qinhuangdao 066004 China

The macro-scale and meso-scale simulation models of stainless steel clad plate were established by DEFORM-3D. The multi-scale coupling simulations of clad plate with different rolling parameters were carried out. The seven pass hot rolling process of stainless steel clad plate was simulated by numerical simulation. By contrasting the vertical stress and the deformation resistance of cladding layer, the rolling reduction rate satisfying interface bonding was obtained. The grain distribution at the center of the substrate layer was analyzed and reasonable hot rolling reduction rates were selected considering their effects on the recrystallization volume percent and the grain size. The results show that the grain size decreases with the increase of reduction rate. However, too much reduction rate will decrease the rate of recrystallization volume percent and the refining effect of grain is not obvious. To ensure uniform grain size distribution, it is most reasonable to set the rolling temperature to 1150°C and the reduction rate to 50%.

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Study on the detection method and measurement system of head flatness error on non-contact detection

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Jixie Gongcheng Xuebao/Journal of Mechanical Engineering 2016年第20期52卷 1-7页

作者： Shan, Zhongde Zhang, Fei Nie, Jungang Ren, Yongxin State Key Laboratory of Advanced Forming Technology and Equipment China Academy of Machinery Science Technology Beijing100083 China

In order to solve the problem of engine cylinder head casting production process of the bottom of the cylinder head surface flatness error detection problem, the design of a laser non-contact cylinder head surface flatness on-line detection system, a method of flatness error detection based on diagonal line is proposed. According to the field flatness detection demand design using laser arm axis and cylinder head horizontal transfer reciprocation engine cylinder head surface flatness error detection system;Through the engine cylinder head surface detection feature point four corners diagonal midline build a mathematical model of the engine cylinder head flatness testing, regression equation to determine the method of least squares plane is ideal plane, calculated flatness error;The laser displacement sensor calibration, given the sensor error calibration regression equation and application of the detection system on different types of engine cylinder head detection. The results showed that: The system has a maximum detection area of 400 mm×2 000 mm, the measurement range of 160-450 mm, the measurement accuracy of 0.03 mm, and simple structure, speed, and is fully capable of reality testing requirements. © 2016 Journal of Mechanical Engineering.

关键词： Error detection

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Error modeling for the leg mechanism of the quadruped walking chair robot

Error modeling for the leg mechanism of the quadruped walkin...

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International Conference on Applied System Innovation, ICASI 2015

作者： Wang, H.B. Wang, S.S. Wen, Y.H. Chen, N. Parallel Robot and Mechatronic System Laboratory of Hebei Province Yanshan University QinhuangdaoHeBei Province China Key Laboratory of Advanced Forging and Stamping Technology and Science Yanshan University QinhuangdaoHeBei Province China

ISBN: (纸本)9781138028937

To reduce the output error of the parallel robot, it is crucial to analyze the pose error of the parallel mechanism. This paper deals with the pose error analysis, and establishes the model for the effects of pose parameters and structural parameters on the accuracy of the leg mechanism. Firstly, based on the research of constraint relations on the leg mechanism of the walking chair robot, the error model is established. Then the influence of structure parameters and pose parameters on the pose error is studied. The results contribute a lot to the determination of the structural parameters and the output error of the control system. © 2016 Taylor & Francis Group, London.

关键词： Errors

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Determination of Elastoplastic Mechanical Properties of the Weld and Heat Affected Zone Metals in Tailor-Welded Blanks by Nanoindentation Test

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Chinese Journal of Mechanical Engineering 2015年第5期28卷 911-918页

作者： MA Xiangdong GUAN Yingping YANG Liu Key Laboratory of Advanced Forming & Stamping Technology and Science of Ministry of Education Yanshan University

The elastoplastic mechanical properties of the weld and heat affected zone metals have comparatively major impact on the forming process of tailor-welded blanks. A few scholars investigated the elastoplastic mechanical properties of the weld and heat affected zone, but they only simply assumed that it was a uniform distribution elastoplastic material different from the base materials. Four types of tailor-welded blanks which consist of ST12 and 304 stainless steel plates are selected as the research objects, the elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals are obtained based on the nanoindentation tests, and the Erichsen cupping tests are conducted by combining numerical simulation with physical experiment. The nanoindentation tests results demonstrate that the elastoplastic mechanical properties of the weld and heat affected zone metals are not only different from the base materials, but also varying between the weld metals and the heat affected zone metals. Comparing the Erichsen cupping test resulted from numerical with that from experimental method, it is found that the numerical value of Erichsen cupping test which consider the elastoplastic mechanical properties of the weld and heat affected zone metals have a good agreement with the experimental result, and the relative error is only 4.8%. The proposed research provides good solutions for the inhomogeneous elastoplastic mechanical properties of the tailor-welded blanks weld and heat affected zone metals, and improves the control performance of tailor-welded blanks forming accuracy.

关键词： tailor-welded blanks elastoplastic mechanical properties nanoindentation test Erichsen cupping test

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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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