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A dislocation-based model for cyclic plastic response of lath martensitic steels

Acta Mechanica Sinica 2022年第2期38卷 110-118,I0004页

作者： Long Yu Wenbin Liu Haonan Sui Ying Liu Huiling Duan State Key Laboratory for Turbulence and Complex System Department of Mechanics ami Engineering ScienceBeijing Innovation Center for Engineering Science and Advanced Technology(BIC-ESAT)College of EngineeringPeking UniversityBeijing 100871China Key Laboratory of High Energy Density Physics Simulation(HEDPS) Center for Applied Physics and Technology(CAPT)and IFSACollaborative Innovation Center of MoEPeking UniversityBeijing 100871China

Softening behavior of lath martensitic steels is related to the coarsening of laths and dislocation evolution during cyclic *** the physical mechanism,we developed a dislocation-based model to study the cyclic plastic response for lath martensitic *** a block,we proposed an interfacial dislocation evolution model to physically present the interaction between mobile dislocations in the block and interfacial dislocations by considering the coarsening mechanism of the ***,the evolution behavior of backstress caused by dislocation pile up at the block boundary has been ***,a hierarchical model based on the elastic-viscoplastic self-consistent(EVPSC)theory is developed,which can realize the scale transition among representative volume element(RVE),prior austenite grains(PAGs)and *** to the proposed model,the effective mechanical responses including the cyclic hysteretic loop and peak stress at different cycles for lath martensitic steel have been theoretically predicted and investigated.

关键词： Lath martensitic steel Cyclic softening Hierarchical microstructure Lath coarsening Crystal plasticity

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Emergent grain boundary phases in stressed polycrystalline thin films

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Physical Review Materials 2023年第8期7卷 083602-083602页

作者： Mengyuan Wang Ruilin Yan Xiao Han Hailong Wang Moneesh Upmanyu CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern Mechanics CAS Center for Excellence in Complex System Mechanics University of Science and Technology of China Hefei Anhui 230027 China Group for Simulation and Theory of Atomic-Scale Material Phenomena (stAMP) Department of Mechanical and Industrial Engineering Northeastern University Boston Massachusetts 02115 USA

The grain boundary (GB) microstructure influences and is influenced by the development of residual stresses during synthesis of polycrystalline thin films. Recent studies have shown that the frustration between the preferred growth direction and rotations of abutting crystals to local cusps in GB energies leads to internal stresses localized within nanoscopic surface layers around the valleys and ridges that form at emergent boundaries (eGBs). Using a combination of continuum frameworks, numerical analyses, and all-atom simulations of bicrystal 〈111〉 copper films, we show that eGBs tune their surface morphology and rotation extent in response to external strains. Compression favors rotation to and growth of low-energy GB phases (complexions) at eGB valleys while tension favors the transitions at eGB ridges, a reflection of the stress-induced mass efflux/influx that changes the energetic balance between interfacial and deformation energies. Molecular dynamics simulations of strained and growing bicrystal films reveal that the eGB phase transition is coupled to island formation at the surface triple junctions, providing a direct link between eGB phases and surface step flow. The interplay between eGB structure, morphology, and mechanics emerges as a crucial ingredient for predictive understanding of stress and morphological evolution during film growth, with broad implications for multifunctional response of polycrystalline surfaces in a diverse range of surface phenomena such as surface-mediated deformation, interfacial embrittlement, thermal grooving, stress corrosion, surface catalysis, and topological conduction.

关键词： Grain boundaries Interface & surface thermodynamics Surface & interfacial phenomena Surface reconstruction Solid-solid interfaces Thin films Molecular dynamics

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Anisotropic Oldroyd-type models for non-colloidal suspensions of viscoelastic particles in Newtonian and yield-stress fluids via homogenization

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science Talks 2022年 4卷

作者： Ponte Castañeda, Pedro Department of Mechanical Engineering and Applied Mechanics Graduate Group of Applied Math and Computational Science University of Pennsylvania Philadelphia United States

This talk presents new rheological models, derived by means of homogenization techniques, for non-colloidal suspensions of particles undergoing finite deformations and rotations under Stokes flow conditions. The particles can be nonlinear viscoelastic, or elasto-viscoplastic, while the suspending fluid can be Newtonian or viscoplastic. The microstructure is described by two microstructural ellipsoids, which are allowed to evolve with the flow, characterizing the shape and orientation of the inclusions and the angular dependence of their distribution in space. The models account for particle interactions through the two-point correlation function for the particle centers, in a way that reproduces exactly classical and more recent estimates for dilute suspensions. While special cases of the models have been considered in earlier publications, novel features of this work include the possibility of multiple inclusion families, physically motivated evolutions laws for the particle distributions and more general rheological behaviors for the matrix and inclusions. The resulting models can be viewed as anisotropic generalizations of Oldroyd's invariant models accounting for statistical measures of the microstructure and their evolution. © 2022 The Author

关键词： Multiphase and particle-laden flows Non-Newtonian flows Particle/fluid flow Rheology Suspensions Yield-stress fluids

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High-order Finite-Volume Central Targeted ENO Family Scheme for Compressible Flows in Unstructured Meshes

arXiv

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arXiv 2023年

作者： Ma, Qihang Chong, Kai Leong Feng, Feng Zhang, Jianhua Wang, Bofu Zhou, Quan Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering Science Shanghai University Shanghai200072 China China Academy of Aerospace Science and Innovation Beijing100176 China Shanghai Institute of Aircraft Mechanics and Control Zhangwu Road Shanghai200092 China School of Microelectronics Key Laboratory of Advanced Display and System Application Ministry of Education Shanghai University Shanghai200072 China Shanghai Frontier Science Center of Mechanoinformatics Shanghai University Shanghai200072 China

The high-order Target ENO (TENO) scheme, known for its innovative weighting strategy, has demonstrated strong potential for complex flow predictions. This study extends the TENO weighting approach to develop non-oscillatory central TENO (CTENO and CTENOZ) family schemes for unstructured meshes. The CTENO schemes employ compact directional stencils, which increase the likelihood of finding stencils within smooth regions. The design is intentionally compact to simplify the implementation of directional stencils. An effective scale separation strategy is adopted using an ENO-like stencil selection method, which employs large central stencils in smooth regions to achieve high-order accuracy, and smaller directional stencils near discontinuities to improve shock-capturing capabilities. Extensive tests involving CWENO, TENO, CTENO, and CTENOZ schemes were conducted to assess their performance in terms of accuracy, robustness, parallel scalability, and computational efficiency. The findings indicate that the proposed CTENO and CTENOZ schemes deliver high-order precision, lower numerical dissipation, and excellent shock-capturing performance. © 2023, CC BY.

关键词： Mesh generation

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Analytical analysis of the bifurcation behavior of creep groan

Analytical analysis of the bifurcation behavior of creep gro...

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作者： Zhao, Xingwei Gräbner, Nils von Wagner, Utz Hetzler, Hartmut State Key Laboratory of Digital Manufacturing Equipment and Technology Department of Mechanical Science and Engineering Huazhong University of Science and Technology China Technische Universität Berlin Germany Applied Dynamics Group Institute for Mechanics Universität Kassel Germany

Creep groan is one of the low frequency vibration phenomena, which can be observed in automotive disk brakes at low driving speeds [1]. In order to study fundamental mechanisms of creep groan, a model with bristle friction law was set up, for which the bifurcation behavior was studied numerically. A corresponding map reflecting regions with qualitatively different behavior was obtained and compared with experimental results [9–11]. In the work described in this paper, an analytical study based on an approach presented in [13, 14] is proposed as an alternative way to map the bifurcation behavior. The corresponding nonlinear model shows that the system may have three different parameter regions with different types of asymptotically stable solutions, i.e. an equilibrium solution, a stick-slip limit cycle, and coexistence of them. The stick-slip limit cycle can be interpreted as the origin of creep groan in a vehicle while the equilibrium solution is the desired non-vibrating solution. As the regions reflect the risk of generation of creep groan, it can be used to evaluate the robustness of brake systems against creep groan. The analytical study is verified by experimental results. © 2019 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

关键词： Stick-slip

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Tunnel effects on ring road traffic flow based on an urgent-gentle class traffic model

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Theoretical & applied mechanics Letters 2021年第4期11卷 230-235页

作者： Yongliang Zhang M.N.Smirnova Jian Ma N.N.Smirnov Zuojin Zhu Faculty of Engineering Science University of Science and Technology of ChinaHefei 230026China Faculty of Mechanics and Mathematics Lomonosov Moscow State UniversityMoscow 119992Russian Federation Moscow Center for Fundamental and Applied Mathematics Moscow 119992Russian Federation Scientific Research Institute for System Analysis Russian Academy of SciencesMoscow 119992Russian Federation Naval Architecture and Civil Engineering Jiangsu University of Science and TechnologyZhenjiang 215600China

To explore tunnel effects on ring road traffic flow,a macroscopic urgent-gentle class traffic model is put *** model identifies vehicles with urgent and gentle classes,chooses the tunnel speed limit as free flow speed to express the fundamental diagram in the tunnel,and adopts algebraic expressions to describe traffic pressure and sound *** two speed trajectories at the Kobotoke tunnel in Japan,the model is validated,with good agreement with observed *** results indicate that in the case of having no ramp effects,tunnel mean travel time is almost constant dependent on tunnel *** initial density normalized by jam density is above a threshold of about 0.21,a traffic shock wave originates at the tunnel entrance and propagates *** a threshold drops slightly as a result of on-ramp merging effect,the mean travel time drops as off-ramp diversion effect intensifies *** findings deepen the understanding of tunnel effects on traffic flow in reality.

关键词： Tunnel effects Travel time Density threshold Ramp effects

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Parametric identification of time-varying systems from free vibration using intrinsic chirp component decomposition

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Acta Mechanica Sinica 2020年第1期36卷 188-205页

作者： Sha Wei Shiqian Chen Xingjian Dong Zhike Peng Wenming Zhang School of Mechanics and Engineering Science Shanghai UniversityShanghai200072China Shanghai Institute of Applied Mathematics and Mechanics Shanghai UniversityShanghai200072China Shanghai Key Laboratory of Mechanics in Energy Engineering Shanghai UniversityShanghai200072China State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong UniversityShanghai200240China

Time-varying systems are applied extensively in practical applications,and their related parameter identification techniques are of great significance for structural health monitoring of time-varying *** improve the identification accuracy for time-varying systems,this study puts forward a novel parameter identification approach in the time-frequency domain using intrinsic chirp component decomposition(ICCD).ICCD is a powerful tool for signal decomposition and parameter extraction,with good signal reconstruction capability in a high-noise *** maintain good identification effects for the time-varying system in a noisy environment,the proposed method introduces a redundant Fourier model for the non-stationary signal,including instantaneous frequency(IF)and instantaneous amplitude(IA).The accuracy and effectiveness of the proposed approach are demonstrated by a single-degree-of-freedom system with three types of time-varying parameters,as well as an example of a multi-degree-of-freedom *** effects of different levels of measured noise on the identified results are also discussed in *** results show that the proposed method is very effective in tracking the smooth,periodical,and non-smooth variations of time-varying systems over the entire identification time period even when the response signal is contaminated by intense noise.

关键词： system identification Time-varying system Time-frequency domain Intrinsic chirp component decomposition

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Precipitation-strengthened micromechanical behaviors of magnesium alloy under cyclic loading

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Journal of Magnesium and Alloys 2024年

作者： Liu, Chuhao Xie, Di Gao, Yanfei Zhang, Xiaodan Zhong, Shengyi Wang, Huamiao An, Ke Liaw, Peter K. Peng, Yinghong State Key Laboratory of Mechanical System and Vibration Shanghai Jiao Tong University Shanghai200240 China Department of Materials Science and Engineering The University of Tennessee KnoxvilleTN37996 United States School of mechanical engineering and automation Fuzhou University Fujian 350116 China School of Materials Science and Engineering Shanghai Jiao Tong University Shanghai200249 China SJTU Paris Elite Institute of Technology Shanghai Jiao Tong University Shanghai200240 China Neutron Scattering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Shanghai Frontier Science Center of Mechanoinformatics Shanghai Institute of Applied Mathematics and Mechanics School of Mechanics and Engineering Science Shanghai University Shanghai200072 China

The microscopic-deformation mechanisms of an extruded magnesium alloy with and without precipitates [Guinier-Preston (GP) zones] subjected to cyclic deformation were investigated by in-situ neutron-diffraction (ND) measurements and crystal-plasticity modeling. The relationship between the macroscopic-cyclic-deformation behavior and the microscopic responses (particularly twinning and detwinning) at the grain level was established. The general deformation-mechanism evolution in the solution-state (ST) sample was similar to that in the peak-aged-state (PA) sample over fatigue cycles. Both samples plastically deformed by extension twinning during compression, and by a sequential process of detwinning and dislocation motion under reverse tension. The main difference is that in the PA sample, the presence of precipitating particles constrains the twinning/detwinning behaviors, which leads to an increase in the participation of dislocation slip in the plastic deformation and then induces a strengthening effect during cyclic loading. Based on the combination of the previous in-situ ND results and crystal-plasticity model, our work provides a comprehensive analysis of the interaction between the precipitation strengthening and twinning/detwinning mechanism under the whole multi-cycle cyclic loading and their effect on the macro- and micro-mechanical behavior of the precipitate-strengthened magnesium alloys. © 2024

关键词： Magnesium alloys

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Technology Roadmap for Flexible Sensors

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ACS NANO 2023年第6期17卷 5211-5295页

作者： Luo, Yifei Abidian, Mohammad Reza Ahn, Jong-Hyun Akinwande, Deji Andrews, Anne M. Antonietti, Markus Bao, Zhenan Berggren, Magnus Berkey, Christopher A. Bettinger, Christopher John Chen, Jun Chen, Peng Cheng, Wenlong Cheng, Xu Choi, Seon-Jin Chortos, Alex Dagdeviren, Canan Dauskardt, Reinhold H. Di, Chong-an Dickey, Michael D. Duan, Xiangfeng Facchetti, Antonio Fan, Zhiyong Fang, Yin Feng, Jianyou Feng, Xue Gao, Huajian Gao, Wei Gong, Xiwen Guo, Chuan Fei Guo, Xiaojun Hartel, Martin C. He, Zihan Ho, John S. Hu, Youfan Huang, Qiyao Huang, Yu Huo, Fengwei Hussain, Muhammad M. Javey, Ali Jeong, Unyong Jiang, Chen Jiang, Xingyu Kang, Jiheong Karnaushenko, Daniil Khademhosseini, Ali Kim, Dae-Hyeong Kim, Il-Doo Kireev, Dmitry Kong, Lingxuan Lee, Chengkuo Lee, Nae-Eung Lee, Pooi See Lee, Tae-Woo Li, Fengyu Li, Jinxing Liang, Cuiyuan Lim, Chwee Teck Lin, Yuanjing Lipomi, Darren J. Liu, Jia Liu, Kai Liu, Nan Liu, Ren Liu, Yuxin Liu, Yuxuan Liu, Zhiyuan Liu, Zhuangjian Loh, Xian Jun Lu, Nanshu Lv, Zhisheng Magdassi, Shlomo Malliaras, George G. Matsuhisa, Naoji Nathan, Arokia Niu, Simiao Pan, Jieming Pang, Changhyun Pei, Qibing Peng, Huisheng Qi, Dianpeng Ren, Huaying Rogers, John A. Rowe, Aaron Schmidt, Oliver G. Sekitani, Tsuyoshi Seo, Dae-Gyo Shen, Guozhen Sheng, Xing Shi, Qiongfeng Someya, Takao Song, Yanlin Stavrinidou, Eleni Su, Meng Sun, Xuemei Takei, Kuniharu Tao, Xiao-Ming Tee, Benjamin C. K. Thean, Aaron Voon-Yew Trung, Tran Quang Wan, Changjin Wang, Huiliang Wang, Joseph Wang, Ming Wang, Sihong Wang, Ting Wang, Zhong Lin Weiss, Paul S. Wen, Hanqi Xu, Sheng Xu, Tailin Yan, Hongping Yan, Xuzhou Yang, Hui Yang, Le Yang, Shuaijian Yin, Lan Yu, Cunjiang Yu, Guihua Yu, Jing Yu, Shu-Hong Yu, Xinge Zamburg, Evgeny Zhang, Haixia Zhang, Xiangyu Zhang, Xiaosheng Zhang, Xueji Zhang, Yihui Zhang, Yu Zhao, Siyuan Zhao, Xuanhe Zheng, Yuanjin Zheng, Yu-Qing Zheng, Zijian Zhou, Tao Zhu, Bowen Zhu, Ming Zhu, Rong Zhu, Yangzhi Zhu, Yong Zou, Guijin Chen, Xiaodong 08-03 Innovis Singapore 138634 Republic of Singapore Innovative Centre for Flexible Devices (iFLEX) School of Materials Science and Engineering Nanyang Technological University Singapore 639798 Singapore Department of Biomedical Engineering University of Houston Houston Texas 77024 United States School of Electrical and Electronic Engineering Yonsei University Seoul 03722 Republic of Korea Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 United States Microelectronics Research Center The University of Texas at Austin Austin Texas 78758 United States Department of Chemistry and Biochemistry California NanoSystems Institute and Department of Psychiatry and Biobehavioral Sciences Semel Institute for Neuroscience and Human Behavior and Hatos Center for Neuropharmacology University of California Los Angeles Los Angeles California 90095 United States Colloid Chemistry Department Max Planck Institute of Colloids and Interfaces 14476 Potsdam Germany Department of Chemical Engineering Stanford University Stanford California 94305 United States Laboratory of Organic Electronics Department of Science and Technology Campus Norrköping Linköping University 83 Linköping Sweden Wallenberg Initiative Materials Science for Sustainability (WISE) and Wallenberg Wood Science Center (WWSC) SE-100 44 Stockholm Sweden Department of Materials Science and Engineering Stanford University Stanford California 94301 United States Department of Biomedical Engineering and Department of Materials Science and Engineering Carnegie Mellon University Pittsburgh Pennsylvania 15213 United States Department of Bioengineering University of California Los Angeles Los Angeles California 90095 United States School of Chemistry Chemical Engineering and Biotechnology Nanyang Technological University Singapore 637457 Singapore Nanobionics Group Department of Chemical and Biological Engineering Monash University Clayton Australia 3800 Monash

Humans rely increasingly on sensors to address grand challenges and to improve quality of life in the era of digitalization and big data. For ubiquitous sensing, flexible sensors are developed to overcome the limitations of conventional rigid counterparts. Despite rapid advancement in bench-side research over the last decade, the market adoption of flexible sensors remains limited. To ease and to expedite their deployment, here, we identify bottlenecks hindering the maturation of flexible sensors and propose promising solutions. We first analyze continued...challenges in achieving satisfactory sensing performance for real-world applications and then summarize issues in compatible sensor-biology interfaces, followed by brief discussions on powering and connecting sensor networks. Issues en route to commercialization and for sustainable growth of the sector are also analyzed, highlighting environmental concerns and emphasizing nontechnical issues such as business, regulatory, and ethical considerations. Additionally, we look at future intelligent flexible sensors. In proposing a comprehensive roadmap, we hope to steer research efforts towards common goals and to guide coordinated development strategies from disparate communities. Through such collaborative

关键词： soft materials mechanics engineering flexible electronics conformable sensors bioelectronics human-machine interfaces body area sensor networks technology translation sustainable electronics

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Design and Implementation of a Low-Cost Non-Invasive Modular Kit for Wheelchair Motorization in Developing Countries

Design and Implementation of a Low-Cost Non-Invasive Modular...

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IEEE International Congress on Electronics, Electrical engineering and Computing (INTERCON)

作者： Anthony Valladolid-Ballon Jesus Flores-Oscanoa Richard Kevin Revilla-Segovia Brayan Yordy Astete-Florez Daniel Lavayen-Farfán Carlos Fosca-Pastor Faculty of Science and Engineering Pontificia Universidad Católica del Perú Lima Perú Applied Mechanics Machines and Mechanisms Research Group Mechanical Engineering Section Pontificia Universidad Católica del Perú Lima Peru Mechanical Engineering Section Pontificia Universidad Católica del Perú Lima Peru

ISBN: (数字)9798350378344

ISBN: (纸本)9798350378351

Wheelchairs are essential for people with reduced mobility. Motorization of these devices can provide an increase quality of living and independence for their users. However, the cost of electric wheelchairs makes them inaccessible to users from developing countries. To address this issue, a low-cost modular kit is proposed, designed and manufactured. The mechatronic design of the kit includes the mechanical design of the components as well as dimensioning, the selection of electronic components, as well as the incorporation of IoT technology to be able to control it using a smartphone if necessary. The resulting modular kit proves to be useful as it can be rapidly installed on a commercial wheelchair without modifying its structure. Preliminary tests of the functional prototype show the wheelchair can provide enhanced mobility to the user, a low turning radius for narrow spaces, as wells as the ability to easily climb up and down on ramps.

关键词： Electrical engineering Mechatronics Costs Wheelchairs Prototypes Electronic components Developing countries Aerospace electronics Turning

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