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Novel technologies for the lost foam casting process
Wenming JIANG, Zitian FAN
《机械工程前沿(英文)》 2018年 第13卷 第1期 页码 37-47 doi: 10.1007/s11465-018-0473-2
Lost foam casting (LFC) is a green precision casting process categorized as a near net forming technology. Yet, despite its popularity, it still suffers from some technological problems, such as poor filling ability of the castings, coarse and non-dense microstructure, low mechanical properties for the Al and Mg LFC processes, and defective carburization for the low carbon steel LFC process. These drawbacks restrict the development and widespread application of the LFC process. To solve these problems, the present study developed several novel LFC technologies, namely, LFC technologies under vacuum and low pressure, vibration solidification, and pressure solidification conditions; expendable shell casting techno- logy; and preparation technology of bimetallic castings based on the LFC process. The results showed that the LFC under vacuum and low pressure evidently improved the filling ability and solved the oxidization problem of the alloys, which is suitable for producing complex and thin-wall castings. The vibration and pressure solidifications increased the compactness of the castings and refined the microstructure, significantly improving the mechanical properties of the castings. The expendable shell casting technology could solve the pore, carburization, and inclusion defects of the traditional LFC method, obtaining castings with acceptable surface quality. Moreover, the Al/Mg and Al/Al bimetallic castings with acceptable metallurgical bonding were successfully fabricated using the LFC process. These proposed novel LFC technologies can solve the current technological issues and promote the technological progress of the LFC process.
关键词: LFC under vacuum and low pressure vibration solidification pressure solidification expendable shell casting bimetallic castings
Premature melt solidification during mold filling and its influence on the as-cast structure
M. WU, M. AHMADEIN, A. LUDWIG
《机械工程前沿(英文)》 2018年 第13卷 第1期 页码 53-65 doi: 10.1007/s11465-017-0437-y
Premature melt solidification is the solidification of a melt during mold filling. In this study, a numerical model is used to analyze the influence of the pouring process on the premature solidification. The numerical model considers three phases, namely, air, melt, and equiaxed crystals. The crystals are assumed to have originated from the heterogeneous nucleation in the undercooled melt resulting from the first contact of the melt with the cold mold during pouring. The transport of the crystals by the melt flow, in accordance with the so-called “big bang” theory, is considered. The crystals are assumed globular in morphology and capable of growing according to the local constitutional undercooling. These crystals can also be remelted by mixing with the superheated melt. As the modeling results, the evolutionary trends of the number density of the crystals and the volume fraction of the solid crystals in the melt during pouring are presented. The calculated number density of the crystals and the volume fraction of the solid crystals in the melt at the end of pouring are used as the initial conditions for the subsequent solidification simulation of the evolution of the as-cast structure. A five-phase volume-average model for mixed columnar-equiaxed solidification is used for the solidification simulation. An improved agreement between the simulation and experimental results is achieved by considering the effect of premature melt solidification during mold filling. Finally, the influences of pouring parameters, namely, pouring temperature, initial mold temperature, and pouring rate, on the premature melt solidification are discussed.
关键词: premature solidification mold filling as-cast structure modeling
《能源前沿(英文)》 2021年 第15卷 第4期 页码 959-973 doi: 10.1007/s11708-021-0753-0
关键词: molten metal spreading solidification particle method severe accident fuel debris decommissioning
Cement-based solidification/stabilization of contaminated soils by nitrobenzene
Jianguo LIU, Xiaoqin NIE, Xianwei ZENG, Zhaoji SU
《环境科学与工程前沿(英文)》 2012年 第6卷 第3期 页码 437-443 doi: 10.1007/s11783-012-0406-y
关键词: solidification/stabilization nitrobenzene contaminated soils powder activated carbon
Improvement of solidification model and analysis of 3D channel blockage with MPS method
《能源前沿(英文)》 2021年 第15卷 第4期 页码 946-958 doi: 10.1007/s11708-021-0754-z
关键词: boiling water reactor (BWR) severe accident channel blockage moving particle semi-implicit (MPS) method solidification
Directional solidification of metal-gas eutectic and fabrication of regular porous metals
LIU Yuan, LI Yanxiang, WAN Jiang
《机械工程前沿(英文)》 2007年 第2卷 第2期 页码 180-183 doi: 10.1007/s11465-007-0030-x
关键词: orientation solid-gas eutectic research solidifying porosity
介万奇
《中国工程科学》 2002年 第4卷 第6期 页码 1-4
从对材料成形加工技术进步的分析入手,论述了凝固技术在材料先进成形加工技术中的应用及其重要性。结合对几种凝固新技术的实例的分析指出,不论是传统材料加工过程“控形—控性(控制组织)—控制成本—控制污染”一体化新技术,还是作为新材料研制手段,凝固技术的重要性均是非常突出的。进而分析了近年来受到广泛重视的凝固过程研究的新课题及其由此可能带来的技术进步。
《机械工程前沿(英文)》 2023年 第18卷 第1期 doi: 10.1007/s11465-022-0730-2
关键词: ultrasonic vibration-assisted grinding perforated ultrasonic vibration platform vibration characteristics apparent elasticity method grinding force surface integrity
朱鸣芳,于金,洪俊杓
《中国工程科学》 2004年 第6卷 第5期 页码 8-16
应用计算机数值模拟技术研究金属凝固显微组织的形成规律是材料科学发展的重要前沿领域之一。文章对该领域的最新研究进展作了简要评述;重点介绍了作者发展的一个改进的MCA(modified cellular automaton)模型的特点以及应用该模型在合金凝固组织 数值模拟方面的一些主要工作。
关键词: 凝固 显微组织 计算机模拟 cellular automaton模型
Hefu Pu, Aamir Khan Mastoi, Xunlong Chen, Dingbao Song, Jinwei Qiu, Peng Yang
《环境科学与工程前沿(英文)》 2021年 第15卷 第4期 doi: 10.1007/s11783-020-1359-1
关键词: Dredged contaminated sediment Dewatering Solidification/stabilization Vacuum preloading Prefabricated horizontal drain Heavy metal
Recent development of vibration utilization engineering
WEN Bangchun
《机械工程前沿(英文)》 2008年 第3卷 第1期 页码 1-9 doi: 10.1007/s11465-008-0017-2
关键词: utilization engineering non-linear vibration vibration utillization utillization engineering
柳百成
《中国工程科学》 2000年 第2卷 第9期 页码 29-37
面向市场经济,迎接全球化竞争的挑战,为国民经济的发展作贡献,就要十分重视制造业特别是铸造行业的发展。但是,我国铸造行业与国外相比有很大差距,它制约着国民经济的发展。世界各国在铸造成形加工技术的发展趋势方面,认识是一致的,即:一是大型工程中特大型铸件的关键铸造技术;二是向精确成形技术方向发展;三是用计算机模拟仿真逐步代替传统的经验性研究方法。铸造过程计算机模拟仿真是改造传统铸造产业的必由之路,是当今世界各国专家学者关注的热点。铸造充型凝固过程的数值模拟可以帮助工程技术.人员优化工艺设计,缩短试制周期、降低生产成本、确保铸件质量,已成为铸造领域最热门的研究课题之一。目前,凝固过程的流场、温度场数值模拟及缩孔缩松预测已应用于实际生产,应力分析、微观组织模拟等方面的基础研究及实用化进程都取得了很大进展。
Guilian YI, Yunkang SUI, Jiazheng DU
《机械工程前沿(英文)》 2011年 第6卷 第2期 页码 229-234 doi: 10.1007/s11465-011-0128-z
To reduce vibration and noise, a damping layer and constraint layer are usually pasted on the inner surface of a gearbox thin shell, and their thicknesses are the main parameters in the vibration and noise reduction design. The normal acceleration of the point on the gearbox surface is the main index that can reflect the vibration and noise of that point, and the normal accelerations of different points can reflect the degree of the vibration and noise of the whole structure. The K-S function is adopted to process many points’ normal accelerations as the comprehensive index of the vibration characteristics of the whole structure, and the vibration acceleration level is adopted to measure the degree of the vibration and noise. Secondary development of the Abaqus preprocess and postprocess on the basis of the Python scripting programming automatically modifies the model parameters, submits the job, and restarts the analysis totally, which avoids the tedious work of returning to the Abaqus/CAE for modifying and resubmitting and improves the speed of the preprocess and postprocess and the computational efficiency.
关键词: Abaqus secondary development Python language vibration and noise reduction K-S function vibration acceleration level
Similitude design for the vibration problems of plates and shells: A review
Yunpeng ZHU, You WANG, Zhong LUO, Qingkai HAN, Deyou WANG
《机械工程前沿(英文)》 2017年 第12卷 第2期 页码 253-264 doi: 10.1007/s11465-017-0418-1
Similitude design plays a vital role in the analysis of vibration and shock problems encountered in large engineering equipment. Similitude design, including dimensional analysis and governing equation method, is founded on the dynamic similitude theory. This study reviews the application of similitude design methods in engineering practice and summarizes the major achievements of the dynamic similitude theory in structural vibration and shock problems in different fields, including marine structures, civil engineering structures, and large power equipment. This study also reviews the dynamic similitude design methods for thin-walled and composite material plates and shells, including the most recent work published by the authors. Structure sensitivity analysis is used to evaluate the scaling factors to attain accurate distorted scaling laws. Finally, this study discusses the existing problems and the potential of the dynamic similitude theory for the analysis of vibration and shock problems of structures.
标题 作者 时间 类型 操作
Premature melt solidification during mold filling and its influence on the as-cast structure
M. WU, M. AHMADEIN, A. LUDWIG
期刊论文
Analysis of molten metal spreading and solidification behaviors utilizing moving particle full-implicit
期刊论文
Cement-based solidification/stabilization of contaminated soils by nitrobenzene
Jianguo LIU, Xiaoqin NIE, Xianwei ZENG, Zhaoji SU
期刊论文
Directional solidification of metal-gas eutectic and fabrication of regular porous metals
LIU Yuan, LI Yanxiang, WAN Jiang
期刊论文
Vibration characteristics and machining performance of a novel perforated ultrasonic vibration platform
期刊论文
An integrated method for the rapid dewatering and solidification/stabilization of dredged contaminated
Hefu Pu, Aamir Khan Mastoi, Xunlong Chen, Dingbao Song, Jinwei Qiu, Peng Yang
期刊论文
Application of python-based Abaqus preprocess and postprocess technique in analysis of gearbox vibration
Guilian YI, Yunkang SUI, Jiazheng DU
期刊论文