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The Influence of temperature on the microstructure and properties of Cu/Al tube joints in magnetic pulse-assisted semi-solid brazing

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Journal of advanced Joining Processes 2025年

作者： Zhenglei Rui Shangyu Huang Huajun Wang Zhenghua Meng School of Materials Science and Engineering Wuhan University of Technology Wuhan 430070 China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan 430070 China

This study addresses the technical challenge of copper/aluminum (Cu/Al) tube joining through the innovative application of magnetic pulse-assisted semi-solid brazing (MPASSB) technology. Through an integrated approach combining finite element simulation with microstructural characterization, this study systematically investigates how brazing temperature (390-440°C) influences the microstructure and mechanical properties of Cu/Al tube joints. Notably, a novel finite element method-smoothed particle hydrodynamics (FEM-SPH) coupling model has been developed. This model enables precise simulation of fluid-solid interactions between tubes and filler metal during the brazing process, providing fresh insights into oxide layer removal mechanisms. The research reveals that brazing temperature serves as the critical parameter governing the elemental diffusion and microstructural evolution in the joint. As the temperature increases from 390°C to 440°C, the viscosity coefficient of the filler metal decreases significantly from 41.6Pa·s to 1.798Pa·s, resulting in enhanced fluidity that promotes interfacial interactions between the tubes and filler metal and effectively removes surface oxide films, thus improving joint quality. However, excessive temperature intensifies the filler metal ejection, increasing the risk of filler metal deficiency at the top of the joint. Mechanical testing demonstrates that joints brazed at 440°C achieve optimal shear strength of 81.1MPa, with fracture occurring at the copper-side (Cu-side) interface between the Al 4.2 Cu 3.2 Zn 0.7 intermetallic phase and the diffusion layer. This work establishes fundamental theoretical guidance for optimizing MPASSB process parameters and facilitates the efficient joining of Cu/Al tubes.

关键词： Brazing temperature Finite element simulation Elemental diffusion Oxide removal Interfacial interaction

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Panel Acoustic Contribution Analysis in automotive Acoustics Using Discontinuous Isogeometric Boundary Element Method

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Computer Modeling in Engineering & Sciences 2023年第6期135卷 2307-2330页

作者： Yi Sun Chihua Lu Zhien Liu Menglei Sun Hao Chen Hubei Key Laboratory of Advanced Technology for Automotive Components(Wuhan University of Technology) Wuhan430070China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Foshan528200China

In automotive industries,panel acoustic contribution analysis(PACA)is used to investigate the contributions of the body panels to the acoustic pressure at a certain point of ***,PACA is implementedmostly by either experiment-based methods or traditional numerical ***,these schemes are effort-consuming and inefficient in solving engineering problems,thereby restraining the further development of PACA in automotive *** this work,we propose a PACA scheme using discontinuous isogeometric boundary element method(IGABEM)to build an easily implementable and efficient method to identify the relative acoustic contributions of each automotive body *** IGABEMis more accurate and converges faster than continuous BEM and IGABEM in the interior sound pressure evaluation of automotive *** this work,a contribution ratio is defined to estimate the relative acoustic contribution of the structure panels;it can be calculated by reusing the coefficient matrix that has already been generated in the sound pressure evaluation *** utilization of the parallel technique enables the proposed method to be more efficient than conventional methods;it is validated in two numerical examples,including a car passenger compartment subjected to realistic boundary conditions.A sound pressure response experiment based on a steel box is conducted to verify the accuracy of the interior sound pressure calculation using discontinuous *** work is expected to promote the practical process of IGABEM for application in automotive acoustic problems.

关键词： PACA IGABEM discontinuous element automotive acoustics

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Phase-field lattice-Boltzmann study on fully coupled thermal-solute-convection dendrite growth of Al-Cu alloy

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China Foundry 2024年第2期21卷 125-136页

作者： Yin-qi Qiu Meng-wu Wu Xun-peng Qin Shou-mei Xiong Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000HubeiChina School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China

Dendrite growth is a complex liquid-solid phase transition process involving multiple physical factors.A phase-field lattice-Boltzmann method was developed to simulate the two-and three-dimension dendrite growth of Al-Cu *** effect of fully coupled thermal-solute-convection interaction on the dendrite growth was investigated by incorporating a parallel-adaptive mesh refinement algorithm into the numerical *** accurately reproducing the latent heat release,solute diffusion and convective transport behaviors at the liquidsolid interface,the interaction mechanism among thermal-solute-convection transport as well as their coupling effects on the dendrite growth dynamics were *** simulation results show that the release of latent heat slows down the dendrite growth rate,and both natural and forced convection disrupt the symmetrical growth of *** combination makes the growth of dendrites more complex,capturing important physical aspects such as recalescence,dendrite tip splitting,dendrite tilting,dendrite remelting,and solute plume in the simulation *** on the robustness and powerful ability of the numerical model,the formation mechanisms of these physical aspects were revealed.

关键词： simulation phase field dendrite growth thermal-solute-convection interaction

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A model for converting thermal analysis to volume fraction of high carbon bearing steels during low-temperature tempering

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Journal of Materials Science & technology 2023年第5期136卷 212-222页

作者： Qinglong Liu Junyu Tian Wenting Wei The State Key Laboratory of Refractories and Metallurgy The Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of EducationWuhan University of Science and TechnologyWuhan 430081China School of Automotive Engineering Wuhan University of TechnologyWuhan 430070China Hubei Key Laboratory of Advanced Technology for Automotive Components(Wuhan University of Technology) Wuhan 430070China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan 430070China

Quantitative prediction of phase content is of great importance to control and optimize the heat treat-ment process of *** this work,a model for predicting the phase content of tempered high carbon steels was proposed by taking a martensitic 100Cr6 bearing steel as a model *** microstructural transformations during tempering were studied using thermal analysis,transmission electron microscopy(TEM),and X-ray diffraction(XRD).Kinetics analysis of thermal evolution by employing the isoconver-sional method,and assisted by TEM and XRD characterization,were performed to quantitatively estimate the volume fractions of different phases after tempering.A series of isothermal tempering experiments were designed to verify the *** predicted results were in good agreement with the experimental results of XRD and electrolytic extraction measurements.

关键词： Bearing steel Martensite tempering Retained austenite Thermal analysis Kinetics

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Cold start performance analysis of PEMFC with different assisted heating strategies

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Case Studies in Thermal Engineering 2025年 71卷

作者： Wenhao Li Jianjun Yang Changqing Du Jie Zhao Qianqian Xin Fuwu Yan Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan China Hubei Research Center for New Energy and Intelligent Connected Vehicle Wuhan University of Technology Wuhan China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Foshan 528200 China

Large-scale use of proton exchange membrane fuel cell (PEMFC) is restricted by the challenge of cold start. A three-dimensional, transient, multiphase flow cold-start model is established to investigate the effects of different assisted heating strategies. The variations of ice volume fraction and temperature distribution of catalyst layer and their influences on cold start performance of PEMFC are discussed in detail, under coolant-assisted heating strategy, air-assisted heating strategy and the combination of two strategies at −20 °C. The results show that coolant-assisted heating strategy has significant effect on the cold start performance. There is an appropriate coolant flow velocity and heating power to balance cold start performance and energy consumption. Air-assisted heating strategy has minimal improvement on the cold start performance. Moreover, an interesting point is that on the basis of coolant-assisted heating adoption, the heat brought by the air-assisted heating although not much but can effectively improve water storage capacity of the ionomer. This makes the combination of two strategies has more excellent cold start performance, namely, catalyst layer's ice volume fraction decreases by 7.7 % and cold start time shortens by 2 s, compared to coolant-assisted heating, which provides valuable information for practical cold start strategy design of PEMFC.

关键词： Proton exchange membrane fuel cell Three-dimensional model Cold start Assisted heating strategy

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Numerical analysis of loaded stress and central displacement of deep groove ball bearing

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Journal of Central South University 2016年第10期23卷 2542-2549页

作者：杨磊邓松李红星 Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology Wuhan 430070 China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of Technology Wuhan 430070 China Zhejiang Tianma Bearing Co. Ltd. Hangzhou 310015 China

The aim of this work is to develop a three-dimensional model of deep groove ball bearing to investigate the loaded stresses and central displacements of bearing rings. The equivalent stresses and central displacements of bearing rings are obtained based on the simulated analysis. Moreover, several parameters, such as load magnitude, raceway groove curvature radius(RGCR), thicknesses of outer and inner rings, are varied to investigate their effects on the equivalent stresses and central displacements of bearing rings. Research results provide useful guidelines for determining the design parameters.

关键词： deep groove ball bearing equivalent stress central displacement

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Hybrid CFD/FEM-BEM simulation of cabin aerodynamic noise for vehicles traveling at high speed

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Science China(Technological Sciences) 2013年第7期56卷 1697-1708页

作者： WANG YiPing ZHEN Xin WU Jing GU ZhengQi XIAO ZhenYi YANG Xue Hubei Key Laboratory of Advanced Technology of Automotive Components Wuhan University of Technology State Key Laboratory of Automotive Simulation and Control Jilin University State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan University Wuhan Ordnance Noncommissioned officers School

Flow passing a vehicle may lead to the increase of the cabin interior noise level through a variety of mechanisms. These mechanisms include vibrations caused by aerodynamic excitations and reradiation from the glass panels, exterior noise trans-mitted and leaked through door seals including gaps and glass edge, and transmission of airborne noise generated by the interaction of flow with body panels. It is of vital importance to predict both the flow fields and the acoustic sources around the ve-hicle to accurately assess the impact of wind induced noise inside the cabin. In the present study, an unstructured segregated finite volume model was used to calculate the flow fields in which a hexahedron grid is used to simplify the vehicle geometry.A large eddy simulation coupled with a wall function model was applied to predict the exterior transient flow fields. The mean flow quantities were thus calculated along the symmetry plane and the vehicle's side windows. A coupled FEM/BEM method was used to compute the vehicle's interior noise level. The total contribution of the interior noise level due to the body panels of the vehicle was subsequently analyzed.

关键词： aerodynamic noise computational fluid dynamics large eddy simulation finite element method boundary element method

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The Effect of Nd^(3+) Concentration on Upconversion Luminescence in Yb^(3+)/Tm^(3+)/Nd^(3+) Tripledoped b-NaGdF_(4) Nanocrystals

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Journal of Wuhan University of technology(Materials Science) 2022年第3期37卷 393-398页

作者： HOU Huayu GAN Lin WANG Youfa WANG Wei State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China School of Automotive Engineering Wuhan University of TechnologyWuhan 430070China Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Collaborative Innovation Center for Automotive Components Technology Wuhan University of TechnologyWuhan 430070China

Nd^(3+)-doped NaGdF_(4):Yb,Tm nanocrystals were synthesized by an improved high-temperature thermal decomposition method,and the effects of doping concentrations on the crystal structure,phase composition,and upconverted fluorescence intensity were also *** results reveal that the introduction of Nd^(3+) ions does not cause the transformation of the crystal phase,but induce the change of the unit cell ***,the fluorescence intensity of the synthesized nanocrystals when co-doped with 3 mol%Nd^(3+) is the strongest under the excitation of 980 nm laser,which is 3.9 times that of the Nd^(3+)-free doped nanoparticles,and the average size is 62.9 *** it is located in the blue area of the CIE coordinate diagram,and the corresponding color purity is 91.81%under the same experimental *** resulting nanocrystals show the potential as excellent fluorescence labeling and in vivo imaging probes.

关键词： upconversion Nd^(3+)doped fluorescence intensity β-NaGdF4

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Effects of process parameters on morphology and distribution of externally solidified crystals in microstructure of magnesium alloy die castings

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China Foundry 2018年第2期15卷 139-144页

作者： Meng-wu Wu Xiao-bo Li Zhi-peng Guo Shou-mei Xiong Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of Technology School of Materials Science and Engineering Tsinghua University

During the cold-chamber high pressure die casting(HPDC) process, samples were produced to investigate the microstructure characteristics of AM60B magnesium alloy. Special attention was paid to the effects of process parameters on the morphology and distribution of externally solidified crystals(ESCs) in the microstructure of magnesium alloy die castings, such as slow shot phase plunger velocity, delay time of pouring and fast shot phase plunger velocity. On the basis of metallographic observation and quantitative statistics, it is concluded that a lower slow shot phase plunger velocity and a longer delay time of pouring both lead to an increment of the size and percentage of the ESCs, due to the fact that a longer holding time of the melt in the shot sleeve will cause a more severe loss of the superheat. The impingement of the melt flow on the ESCs is more intensive with a higher fast shot phase plunger velocity, in such case the ESCs reveal a more granular and roundish morphology and are dispersed throughout the cross section of the castings. Based on analysis of the filling and solidification processes of the melt during the HPDC process, reasonable explanations were proposed in terms of the nucleation, growth, remelting and fragmentation of the ESCs to interpret the effects of process parameters on the morphology and distribution of the ESCs in the microstructure of magnesium alloy die castings.

关键词： magnesium alloy high pressure die casting microstructure externally solidified crystals process parameters

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Effect of Mn addition on microstructure and mechanical properties of GX40CrNiSi25-12 austenitic heat resistant steel

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China Foundry 2024年第3期21卷 205-212页

作者： Guan-yu Jiang Meng-wu Wu Xiao-guang Yang Hui Wang Yu-yuan Zhu Hubei Key Laboratory of Advanced Technology for Automotive Components Wuhan University of TechnologyWuhan 430070China Hubei Longzhong Laboratory Xiangyang 441000HubeiChina Wescast Industries(China)Co. Ltd.Wuhan 430100China

Three types of steels were designed on the basis of GX40CrNiSi25-12 austenitic heat resistant steel by adding different Mn contents(2wt.%,6wt.%,and 12wt.%).Thermodynamic calculation,microstructure characterization and mechanical property tests were conducted to investigate the effect of Mn addition on the microstructure and mechanical properties of the austenitic heat resistant *** show that the matrix structure in all the three types of steels at room temperature is completely *** NbC and M_(23)C_(6)precipitate at grain boundaries of austenite *** the increase of Mn content,the number of carbides increases and their distribution becomes more *** the Mn content increases from 1.99%to 12.06%,the ultimate tensile strength,yield strength and elongation increase by 14.6%,8.0%and 46.3%,*** improvement of the mechanical properties of austenitic steels can be explained by utilizing classic theories of alloy strengthening,including solid solution strengthening,precipitation strengthening,and grain *** increase in alloy strength can be attributed to solid solution strengthening and precipitation strengthening caused by the addition of *** improvement of the plasticity of austenitic steels can be explained from two aspects:grain refinement and homogenization of precipitated phases.

关键词： austenitic heat resistant steel manganese microstructure mechanical properties

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