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Hot deformation behavior of a novel bimetal consisting of BTW1 and Q345R characterized by processing maps

Pengtao LIU, Lifeng MA, Weitao JIA, Tao WANG, Guanghui ZHAO

《机械工程前沿(英文)》 2019年 第14卷 第4期   页码 489-495 doi: 10.1007/s11465-019-0554-x

摘要: Only a few studies have been conducted on the flow behavior of the novel BTW1/Q345R bimetal, which is widely used in coal equipment. In this work, compression tests were conducted on BTW1/Q345R bimetal at a temperature range of 950 °C–1200 °C and strain rates of 0.05, 0.5, 5, and 15 s by using a Gleeble-3800 thermomechanical simulator. A constitutive equation was validated by referring to the Arrhenius equation during the characterization of hot workability. The computed apparent activation energy of the BTW1/Q345R bimetal was 360 kJ/mol, and processing maps under different strain conditions were drawn. Analysis of the stress-strain relationship revealed that work hardening exerted a dominant effect on the thermal deformation of the BTW1/Q345R bimetal. The processing maps predicted that the optimal processing interval will increase with strain. Results showed that thermal deformation of the BTW1/Q345R bimetal should proceed when the temperature range varies from 1182 °C to 1200 °C and the strain rate interval is from 4.2 to 15 s .

关键词: BTW1/Q345R bimetal     constitutive equation     processing map     work hardening    

The psychology of organizational and social sustainability

Wei-Tau LEE, Hao ZHANG, Kenneth H. FUNK II

《工程管理前沿(英文)》 2019年 第6卷 第3期   页码 336-350 doi: 10.1007/s42524-019-0029-0

摘要: This paper presents 12 dimensions of work with the aim of providing further understanding of the relationship between work and the psychological well-being of workers. Previous research has indicated that these dimensions are significant in establishing such a relationship, which is essential to creating good work. These dimensions are also influential in their effect on the psychological state of workers and are translated specifically into actionable items in the workplace. A hypothetical system model is developed to relate these dimensions to one another, to workers, and to organizations. This set of dimensions also serves as a basis for further development of work design and evaluation tools.

关键词: work design     work dimensions     psychological factors     good work    

Basic model study on efficiency evaluation in collaborative design work process

XIE Qiu, YANG Yu, LI Xiaoli, ZHAO Ningyu

《机械工程前沿(英文)》 2007年 第2卷 第3期   页码 344-349 doi: 10.1007/s11465-007-0060-4

摘要: During the efficiency evaluation process of collaborative design work, because of the lack of efficiency evaluation models, a basic analytical model for collaborative design work efficiency evaluation is proposed in this paper. First, the characteristics of the networked collaborative design system work process were studied; then, in accordance with those characteristics, a basic analytical model is created. This model, which is built for centralized collaborative design work, includes an analytical frame, a process view model, a function view model and an information view model. Finally, the application process and steps of this basic analytical model are elaborated when used for efficiency evaluation through an experiment.

关键词: function     system work     evaluation process     efficiency evaluation     design work    

Heat, mass, and work exchange networks

Zhiyou CHEN, Jingtao WANG

《化学科学与工程前沿(英文)》 2012年 第6卷 第4期   页码 484-502 doi: 10.1007/s11705-012-1221-5

摘要: Heat (energy), water (mass), and work (pressure) are the most fundamental utilities for operation units in chemical plants. To reduce energy consumption and diminish environment hazards, various integration methods have been developed. The application of heat exchange networks (HENs), mass exchange networks (MENs), water allocation heat exchange networks (WAHENs) and work exchange networks (WENs) have resulted in the significant saving of energy and water. This review presents the main works related to each network. The similarities and differences of these networks are also discussed. Through comparing and discussing these different networks, this review inspires researchers to propose more efficient and convenient methods for the design of existing exchange networks and even new types of networks including multi-objective networks for the system integration in order to enhance the optimization and controllability of processes.

关键词: process system engineering     integration methods     heat exchange network     mass exchange network     work exchange network    

Strengthening of the concrete face slabs of dams using sprayable strain-hardening fiber-reinforced cementitious

《结构与土木工程前沿(英文)》 2022年 第16卷 第2期   页码 145-160 doi: 10.1007/s11709-022-0806-4

摘要: In this study, sprayable strain-hardening fiber-reinforced cementitious composites (FRCC) were applied to strengthen the concrete slabs in a concrete-face rockfill dam (CFRD) for the first time. Experimental, numerical, and analytical investigations were carried out to understand the flexural properties of FRCC-layered concrete slabs. It was found that the FRCC layer improved the flexural performance of concrete slabs significantly. The cracking and ultimate loads of a concrete slab with an 80 mm FRCC layer were 132% and 69% higher than those of the unstrengthened concrete slab, respectively. At the maximum crack width of 0.2 mm, the deflection of the 80-mm FRCC strengthened concrete slab was 144% higher than that of the unstrengthened concrete slab. In addition, a FE model and a simplified analytical method were developed for the design and analysis of FRCC-layered concrete slabs. Finally, the test result of FRCC leaching solution indicated that the quality of the water surrounding FRCC satisfied the standard for drinking water. The findings of this study indicate that the sprayable strain-hardening FRCC has a good potential for strengthening hydraulic structures such as CFRDs.

关键词: strain-hardening cementitious composites     engineered cementitious composites     sprayable     shotcrete     strengthening     concrete-face rockfill dam     digital image correlation    

Rheological behavior’s effect on the work performance of oil film

Zhaomiao LIU, Qiuying JIN, Chengyin ZHANG, Feng SHEN

《机械工程前沿(英文)》 2011年 第6卷 第2期   页码 254-262 doi: 10.1007/s11465-011-0129-y

摘要:

A 3D model of hydrostatic turntable’s oil chamber is established to investigate the lubricants performance with different rheological properties by using FLUENT software and the finite volume method. Newtonian oil and non-Newtonian oil’s performance under varied speeds are compared on the large size hydrostatic turntable system considering the temperature-viscosity relationship and pressure-viscosity relationship. The results show that the property of non-Newtonian fluid viscosity influenced by shear rate largely affects the lubricants performance for most oil added polymer additives. Lubricants cannot simply be regarded as Newtonian fluid. The shear thickening non-Newtonian fluid has a better work property. The results are important to design a large size and high-speed hydrostatic support system, choose lubricant oils, and investigate oil film’s work properties.

关键词: non-Newtonian fluid     rotation speed     pressure on wall     viscosity    

Printability and hardening performance of three-dimensionally-printed geopolymer based on lunar regolith

《结构与土木工程前沿(英文)》 doi: 10.1007/s11709-023-0003-0

摘要: Using an in situ lunar regolith as a construction material in combination with 3D printing not only reduces the weight of materials carried from the Earth but also improves the automation of lunar infrastructure construction. This study aims to improve the printability of a geopolymer based on a BH-1 lunar regolith simulant, including the extrudability, open time, and buildability, by controlling the temperature and adding admixtures. Rheological parameters were used to represent printability with different water-to-binder ratios, printing temperatures, and contents of additives. The mechanical properties of the hardening geopolymer with different filling paths and loading directions were tested. The results show that heating the printed filaments with a water-to-binder ratio of 0.32 at 80 °C can adjust the printability without adding any additive, which can reduce the construction cost of lunar infrastructure. The printability of the BH-1 geopolymer can also be improved by adding 0.3% Attagel-50 and 0.5% polypropylene fiber by mass at a temperature of 20 °C to cope with the changeable environmental conditions on the Moon. After curing under a simulated lunar environment, the 72-h flexural and compressive strengths of the geopolymer specimens reach 4.1 and 48.1 MPa, respectively, which are promising considering that the acceleration of gravity on the Moon is 1/6 of that on the Earth.

关键词: geopolymer     lunar regolith simulant     3D printing     rheology     printability    

Robotized machining of big work pieces: Localization of supporting heads

Wojciech SZYNKIEWICZ, Teresa ZIELIŃSKA, Włodzimierz KASPRZAK

《机械工程前沿(英文)》 2010年 第5卷 第4期   页码 357-369 doi: 10.1007/s11465-010-0103-0

摘要: A planner for a self adaptable and reconfigurable fixture system is proposed. The system is composed of mobile support agents that support thin sheet metal parts to minimize part dimensional deformation during drilling and milling operations. Compliant sheet metal parts are widely used in various manufacturing processes including automotive and aerospace industries. The main role of the planner is to generate an admissible plan of relocation of the mobile agents. It has to find the admissible locations for the supporting heads that provide continuous support in close proximity to the tool and trajectories of the mobile bases characterized by very high speeds during the relocation phases.

关键词: fixture     robot     milling     drilling    

Seismic analysis of steel structures considering damage cumulation

SHEN Zuyan, WU Aihui

《结构与土木工程前沿(英文)》 2007年 第1卷 第1期   页码 1-11 doi: 10.1007/s11709-007-0001-7

摘要: The research on the development of a reliable analytical model for seismic analysis of steel structures is presented. The non-linear damage cumulation hysteretic model incorporating the deterioration of stiffness, strength and strain hardening for structural steel is proposed and validated. The complete loading history, energy dissipation and the effect of the maximum plastic strain are taken into account in the model. The constants in the model are determined from regression analysis of experimental results of simple standard tensile and cyclic tests. Finite element formulations for beam and structural solid element considering the damage cumulation are derived. A computer program capable of calculating the hysteretic model of steel members, predicting the damage state and crack initiation, and carrying out non-linear time history seismic analysis of steel structures is developed. Solutions obtained from the model are in good agreement with experimental results. It was demonstrated that the damage cumulation effect is considerable and important in structural seismic analysis.

关键词: hardening     regression analysis     computer program     cumulation hysteretic     strength    

Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

《环境科学与工程前沿(英文)》 2007年 第1卷 第4期   页码 418-433 doi: 10.1007/s11783-007-0068-3

摘要: The challenge of making central requirements work at local levels is a common problem for environmental governance throughout the world. Countries can learn from one another s approaches, but must understand the local context in w

Traces and echoes of De Architectura by Marcus Vitruvius Pollio in the work of Xu Guangqi in 17th

Michela CIGOLA,Yibing FANG

《机械工程前沿(英文)》 2016年 第11卷 第1期   页码 3-11 doi: 10.1007/s11465-015-0359-5

摘要:

This study aims to investigate the role played by Xu Guangqi (1562–1633), minister of the Ming Dynasty, in the development of European scientific and technical knowledge in China between the 16th and 17th centuries by analyzing a book of Western technology that he wrote, namely, Taixi Shuifa (On Western Hydraulics). Several Western books related to machine knowledge are searched to trace the source of the illustrations in Taixi Shuifa. We found that Archimedes’ screw and Ctesibius’ machine, which are included in Vitruvius’ De Architectura volumes, also appear in the work of Xu Guangqi.

关键词: Vitruvius’ De Architectura     Xu Guangqi’s Taixi Shuifa     Jesuit missionaries     Italian Renaissance     drawing     representation    

液压挖掘机工作装置的动力特性修改研究

杨为,冯培恩,秦大同

《中国工程科学》 2005年 第7卷 第9期   页码 30-33

摘要:

为提高液压挖掘机工作装置动态性能的优化效率,在对该结构进行试验模态研究的基础上,用双模态空间动力修改方法进行了动力特性修改研究,研究结果表明:质量修改对该结构的1阶、2阶固有频率和阻尼比有显著影响,对其他阶结构动态特性的影响很小;刚度修改对该结构1阶至5阶的固有频率和阻尼比均有明显影响,高阶的固有频率和阻尼比对刚度的变化敏感。所得到的结论揭示了模态参数调整对液压挖掘机工作装置动力特性的影响规律,为提高机械产品的总体质量奠定了基础。

关键词: 双模态空间动力修改法     模态     液压挖掘机     工作装置    

Stress-strain relationship with soil structural parameters of collapse loess

SHAO Shengjun, LONG Jiyong, YU Qinggao

《结构与土木工程前沿(英文)》 2008年 第2卷 第2期   页码 151-160 doi: 10.1007/s11709-008-0020-z

摘要: Through the tri-axial shearing tests of unsaturated intact loess and based on the concept of comprehensive soil structural potential, this paper reveals the changing laws of soil structural property under the tri-axial stress conditions and establishes a mathematical expression equation of structural parameters, whereby reflecting the effects of unsaturated loess water content, stress and strain states, which is introduced into the shearing stress and shearing strain relation to obtain the structural stress-strain relation. The tests reveal that the loess dilatancy is of shearing contraction and shearing expansion, whereby indicating that there is a good linear relation between the stress ratio and shearing expansion strain ratio. The larger consolidation confining pressure is, the larger the stress of shearing contraction and expansion critical point is; and the larger water content is, the smaller the strain ratio of shearing contraction and expansion critical point is. Finally, the constitutive model is established to reflect the variation in loess structure, stress-strain softening and hardening, and shearing contraction and shearing expansion features. Through the comparative analysis, the stress-strain curves described by the constitutive relationship are found to be in good conformity with test results, whereby testing the rationality of the model in this paper.

关键词: hardening     shearing expansion     unsaturated     structural property     mathematical expression    

如果全球定位系统失灵了怎么办?

Mitch Leslie

《工程(英文)》 2019年 第5卷 第6期   页码 985-986 doi: 10.1016/j.eng.2019.10.007

Effect of styrene-butadiene-styrene copolymer on the aging resistance of asphalt: An atomistic understanding from reactive molecular dynamics simulations

《结构与土木工程前沿(英文)》 2021年 第15卷 第5期   页码 1261-1276 doi: 10.1007/s11709-021-0761-5

摘要: To reveal the potential influence of styrene-butadiene-styrene (SBS) polymer modification on the anti-aging performance of asphalt, and its mechanism, we explored the aging characteristics of base asphalt and SBS-modified asphalt by reaction force field (ReaxFF) and classical molecular dynamics simulations. The results illustrate that the SBS asphalt is more susceptible to oxidative aging than the base asphalt under oxygen-deficient conditions due to the presence of unsaturated C=C bonds in the SBS polymer. In the case of sufficient oxygen, the SBS polymer inhibits the oxidation of asphalt by restraining the diffusion of asphalt molecules. Compared with the base asphalt, the SBS asphalt exhibits a higher degree of oxidation at the early stage of pavement service and a lower degree of oxidation in the long run. In addition, SBS polymer degrades into small blocks during aging, thus counteracting the hardening of aged asphalt and partially restoring its low-temperature cracking resistance.

关键词: SBS asphalt     oxidative aging     asphalt hardening     ReaxFF     molecular dynamics    

标题 作者 时间 类型 操作

Hot deformation behavior of a novel bimetal consisting of BTW1 and Q345R characterized by processing maps

Pengtao LIU, Lifeng MA, Weitao JIA, Tao WANG, Guanghui ZHAO

期刊论文

The psychology of organizational and social sustainability

Wei-Tau LEE, Hao ZHANG, Kenneth H. FUNK II

期刊论文

Basic model study on efficiency evaluation in collaborative design work process

XIE Qiu, YANG Yu, LI Xiaoli, ZHAO Ningyu

期刊论文

Heat, mass, and work exchange networks

Zhiyou CHEN, Jingtao WANG

期刊论文

Strengthening of the concrete face slabs of dams using sprayable strain-hardening fiber-reinforced cementitious

期刊论文

Rheological behavior’s effect on the work performance of oil film

Zhaomiao LIU, Qiuying JIN, Chengyin ZHANG, Feng SHEN

期刊论文

Printability and hardening performance of three-dimensionally-printed geopolymer based on lunar regolith

期刊论文

Robotized machining of big work pieces: Localization of supporting heads

Wojciech SZYNKIEWICZ, Teresa ZIELIŃSKA, Włodzimierz KASPRZAK

期刊论文

Seismic analysis of steel structures considering damage cumulation

SHEN Zuyan, WU Aihui

期刊论文

Making central-local relations work: Comparing America and China environmental governance systems

Dan GUTTMAN, SONG Yaqin

期刊论文

Traces and echoes of De Architectura by Marcus Vitruvius Pollio in the work of Xu Guangqi in 17th

Michela CIGOLA,Yibing FANG

期刊论文

液压挖掘机工作装置的动力特性修改研究

杨为,冯培恩,秦大同

期刊论文

Stress-strain relationship with soil structural parameters of collapse loess

SHAO Shengjun, LONG Jiyong, YU Qinggao

期刊论文

如果全球定位系统失灵了怎么办?

Mitch Leslie

期刊论文

Effect of styrene-butadiene-styrene copolymer on the aging resistance of asphalt: An atomistic understanding from reactive molecular dynamics simulations

期刊论文