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Science China(Technological Sciences) 2009年第1期52卷 172-175页

作者： allison john Research & Advanced Engineering Department Scientific Research Laboratory Ford Motor Company

The current paper focuses on the influence of the process parameters on the peak values of the inter-facial heat transfer coefficient (IHTC) at metal/die interface during high pressure die casting (HPDC) process. A "step shape" casting and AM50 alloy were used during the experiment. The IHTC was de-termined by solving the inverse thermal problem based on the measured temperature inside the die. Results show that the initial die surface temperature (IDST, TDI) has a dominant influence while the casting pressure and fast shot velocity have a secondary influence on the IHTC peak values. By curve fitting, it was found that the IHTC peak value (hmax) changes as a function of the IDST in a manner of hmax =eαTγDI. Such relationship between the IHTC peak value and the IDST can also be found when the casting alloy is ADC12, indicating that this phenomenon is a common characteristic in the HPDC process.

关键词： high pressure die casting interfacial heat transfer coefficient AM50 ADC12

THE GEANT4 VISUALIZATION SYSTEM—A MULTI-DRIVER GRAPHICS SYSTEM

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International Journal of Modeling, Simulation, and Scientific Computing 2013年第S1期4卷 1-19页

作者： john allison LAURENT GARNIER AKINORI KIMURA JOSEPH PER School of Physics and Astronomy The University of Manchester ManchesterM139PLUK and GEANT4 Associates International Ltd.9 Royd Terrace Hebden BridgeHX77BTUK John Laboratoire de l’Acc´el´erateur Lin´eaire 91898 Orsay cedexFrance Ashikaga Institute of Technology 268-1 Omae-choAshikaga CityTochigi 326-8558Japan SLAC National Accelerator Laboratory 2575 Sand Hill RoadMenlo ParkCA 94025-7015USA

From the beginning,the Geant4 Visualization System was designed to support several simultaneous graphics systems written to common abstract ***,it has matured into a powerful diagnostic and presentational *** comes with a library of models that may be added to the current scene and which include the representation of the Geant4 geometry hierarchy,simulated trajectories and user-written hits and *** workhorse is the OpenGL suite of drivers for X,Xm,Qt,and *** is an Open Inventor *** can be exported in special graphics formats for offline viewing in the DAWN,VRML,HepRApp and gMocren *** can be generated through OpenGL,Open Inventor,DAWN and ***4’s own tracking algorithms are used by the Ray *** all drivers support all features but all drivers bring added functionality of some *** paper describes the interfaces and details the individual drivers.

关键词： Geant4 simulation radiation modeling graphics ray tracing.

A combined experimental and crystal plasticity study of grain size effects in magnesium alloys

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Journal of Magnesium and Alloys 2023年第12期11卷 4445-4467页

作者： Aaditya Lakshmanan Mohsen Taheri Andani Mohammadreza Yaghoobi john allison Amit Misra Veera Sundararaghavan Department of Aerospace Engineering University of MichiganAnn ArborMI48105USA Department of Materials Science and Engineering University of MichiganAnn ArborMI48105USA Department of Mechanical Engineering University of MichiganAnn ArborMI48105USA

This work presents a method to incorporate the micro Hall-Petch equation into the crystal plasticity finite element(CPFE) framework accounting for the microstructural features to understand the coupling between grain size, texture, and loading direction in magnesium *** effect of grain size and texture is accounted for by modifying the slip resistances of individual basal and prismatic systems based on the micro Hall-Petch equation. The modification based on the micro Hall-Petch equation endows every slip system at each microstructural point with a slip system-level grain size and maximum compatibility factor, which are in turn used to modify the slip resistance. While the slip-system level grain size is a measure of the grain size, the maximum compatibility factor encodes the effect of the grain boundary on the slip system resistance modification and is computed based on the Luster-Morris factor. The model is calibrated using experimental stress-strain curves of Mg-4Al samples with three different grain sizes from which the Hall-Petch coefficients are extracted and compared with Hall-Petch coefficients predicted using original parameters from previous work. The predictability of the model is then evaluated for a Mg-4Al sample with different texture and three grain sizes subjected to loading in different directions. The calibrated parameters are then used for some parametric studies to investigate the variation of Hall-Petch slope for different degrees of simulated spread in basal texture,variation of Hall-Petch slope with loading direction relative to basal poles for a microstructure with strong basal texture, and variation of yield strength with change in grain morphology. The proposed approach to incorporate the micro Hall-Petch equation into the CPFE framework provides a foundation to quantitatively model more complicated scenarios of coupling between grain size, texture and loading direction in the plasticity of Mg alloys.

关键词： Hall-Petch Crystal plasticity Grain size Texture Magnesium alloys

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应用两相流模型模拟压铸充型过程的卷气现象

金属学报 2009年第10期45卷 1153-1158页

作者：李帅君熊守美 Mei Li john allison 清华大学机械工程系先进成形制造教育部重点实验室北京100084 Research & Advanced Engineering Department Scientific Research LaboratoryFord Motor Company

通过对压铸充型过程中卷气缺陷形成机理的分析,认为型腔中空气的流动以及与金属液之间的相互作用是形成卷气现象的主要原因.为了考虑型腔中空气的流动,采用了一种不可压缩两相流数学模型来模拟压铸充型过程的卷气现象.通过计算流体力学... 详细信息

通过对压铸充型过程中卷气缺陷形成机理的分析,认为型腔中空气的流动以及与金属液之间的相互作用是形成卷气现象的主要原因.为了考虑型腔中空气的流动,采用了一种不可压缩两相流数学模型来模拟压铸充型过程的卷气现象.通过计算流体力学中的两个基准算例,较为全面地验证了该模型的准确性和可靠性.在此基础上,设计了专门针对压铸充型过程的高速水模拟实验,通过对可视化实验结果与两相流模拟结果的比较,证实二者吻合较好,说明了该模型能够较好地模拟液体的充填行为和卷入其中的气泡.

关键词：压铸卷气两相流模拟

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压铸充型过程中卷气现象的数值模拟研究

金属学报 2010年第5期46卷 554-560页

作者：李帅君熊守美 Mei Li john allison 清华大学机械工程系汽车安全与节能国家重点实验室北京100084 Research &: Advanced Engineering Department Scientific Research Laboratory FordMotor Company Dearborn MI 48121 USA

采用一种液-气两相耦合模型模拟了压铸充型过程中的卷气现象,对卷入金属液中的每个气泡均单独计算其压力变化的趋势,通过压力传递将液-气两相联系在一起.为了验证模型的可靠性和准确性,开展了专门针对压铸的高速水模拟实验,并采用液-气... 详细信息

采用一种液-气两相耦合模型模拟了压铸充型过程中的卷气现象,对卷入金属液中的每个气泡均单独计算其压力变化的趋势,通过压力传递将液-气两相联系在一起.为了验证模型的可靠性和准确性,开展了专门针对压铸的高速水模拟实验,并采用液-气两相耦合模型以及单相流模型分别进行了模拟,通过比较可以证实两相耦合模型在模拟卷气方面比单相流模型具有更高的精确度.

关键词：压铸卷气液-气两相耦合模型

压铸过程中铸件-铸型界面换热系数与铸件凝固速率的关系

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金属学报 2009年第1期45卷 102-106页

作者：郭志鹏熊守美 Mei Li john allison 清华大学机械工程系先进成形制造教育部重点实验室北京100084 Research ＆ Advanced Engineering Department Scientific Research Laboratory Ford Motor Company Dearborn MI 48121 USA

在实际压铸实验的基础上,求解了铸件-铸型界面换热系数h与铸件凝固速率v的关系.结果表明,二者呈线性变化关系:h=k_(h-v)·v+ω(其中,斜率k_(h-v)为铸型初始表面温度及铸件厚度的函数,ω为常数);通过线性拟合确定k_(h-v)和ω值,从而确立... 详细信息

在实际压铸实验的基础上,求解了铸件-铸型界面换热系数h与铸件凝固速率v的关系.结果表明,二者呈线性变化关系:h=k_(h-v)·v+ω(其中,斜率k_(h-v)为铸型初始表面温度及铸件厚度的函数,ω为常数);通过线性拟合确定k_(h-v)和ω值,从而确立换热系数与铸件凝固速率的关系.这种关系同时适用于镁合金AM50和铝合金ADC12.

关键词：压铸界面换热系数凝固速率镁合金AM50 铝合金ADC12

铸造压力对ADC12Z压铸件孔洞和力学性能的影响

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铸造 2007年第11期56卷 1171-1174页

作者：闫焉服熊守美柳百成 Mei Li john allison 清华大学机械工程系北京100084 福特公司科学研究试验室美国底特律M148121

测定了不同铸造压力下ADC12Z压铸件密度、孔洞面积百分比、孔洞平均直径及力学性能,研究了铸造压力对ADC12Z压铸件孔洞和力学性能影响。结果表明,随着铸造压力增大,压铸件孔洞面积百分比和平均粒径逐渐减小,密度逐渐增大;同时,铸造压力... 详细信息

测定了不同铸造压力下ADC12Z压铸件密度、孔洞面积百分比、孔洞平均直径及力学性能,研究了铸造压力对ADC12Z压铸件孔洞和力学性能影响。结果表明,随着铸造压力增大,压铸件孔洞面积百分比和平均粒径逐渐减小,密度逐渐增大;同时,铸造压力增大可以细化α-Al和黑色针片状共晶Si,使压铸件力学性能明显改善。但当铸造压力增加到一定程度,压力的增加对密度、孔洞及性能影响幅度变小。

关键词：铸造压力孔洞力学性能 ADC12Z合金

Understanding of the influence of process parameters on the heat transfer behavior at the metal/die interface in high pressure die casting process

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中国科学:技术科学 2010年第4期 455-455页

作者： allison john Research & Advanced Engineering Department Scientific Research LaboratoryFord Motor Company

The current paper focuses on the influence of the process parameters on the peak values of the interfacial heat transfer coefficient(IHTC)at metal/die interface during high pressure die casting(HPDC)process.A"step shape"casting and AM50 alloy were used during the *** IHTC was determined by solving the inverse thermal problem based on the measured temperature inside the *** show that the initial die surface temperature(IDST,TDI)has a dominant influence while the casting pressure and fast shot velocity have a secondary influence on the IHTC peak *** curve fitting,it was found that the IHTC peak value(hmax)changes as a function of the IDST in a manner of hmax=e αTγ DI .Such relationship between the IHTC peak value and the IDST can also be found when the casting alloy is ADC12,indicating that this phenomenon is a common characteristic in the HPDC process.

关键词： high pressure die casting interfacial heat transfer coefficient AM50 ADC12

核合金的基于晶体塑性模型的集成计算材料模拟研究

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中国科学：物理学、力学、天文学 2019年第11期49卷 89-102页

作者：马显锋位东辉 allison john E 王彪中山大学中法核工程与技术学院珠海519082 Department of Materials Science and Engineering University of MichiganAnn Arbor 48109USA

核反应堆的核燃料包壳、堆内构件、蒸汽发生器等关键部件均采用耐高温腐蚀、力学性能优异的合金材料制造.合金加工工艺直接影响组织结构,进而影响其力学、腐蚀和辐照性能.核合金的堆外性能研究是合金适用性评估和改进优化的关键步骤,因... 详细信息

核反应堆的核燃料包壳、堆内构件、蒸汽发生器等关键部件均采用耐高温腐蚀、力学性能优异的合金材料制造.合金加工工艺直接影响组织结构,进而影响其力学、腐蚀和辐照性能.核合金的堆外性能研究是合金适用性评估和改进优化的关键步骤,因此定量预测核级合金的"加工工艺-微结构-力学性能"具有重要意义.传统的核合金工艺改进与评估主要依赖于实验循环"试错法",实验成本高,研发周期长.基于全过程模拟的集成计算材料工程方法将制造工艺、材料演化与性能模型结合,显著缩短关键材料及构件的研发周期和成本.为促进该方法在核合金的工艺优化与研发中的应用,本文发展了基于合金微结构相关的晶体塑性模型和解耦有限元模拟的计算方法,对锆合金、钛合金和FeCrAl合金的"加工工艺-织构-力学性能"进行了定量预测.结果显示该集成计算方法可精确预测3种典型合金的热加工织构演化、拉伸和压缩塑性变形行为,可为核级合金的加工工艺优化和力学性能评估提供计算工具和理论依据.

关键词：集成计算材料工程晶体塑性模型加工工艺组织演化织构核合金

Proceedings of the 1st World Congress on Integrated Computational Materials Engineering (ICME) 1

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