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Improving the mechanical properties and thermal conductivity of mesophase-pitch-based carbon fibers by controlling the temperature in industrial spinning equipment

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Carbon 2024年 226卷

作者： Gao-ming Ye Kui Shi Huang Wu Dong Huang Chong Ye Ting Ouyang Shi-peng Zhu Zhen Fan Hong-bo Liu Jin-shui Liu College of Materials Science and Engineering Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology Hunan University Changsha 410082 China Hunan Province Engineering Research Center for High Performance Pitch-based Carbon Materials Hunan Toyi Carbon Material Technology Co. Ltd. Changsha 410000 China State Key Laboratory of Advanced Design and Manufacturing for vehicle body Hunan University Changsha 410082 China Key Laboratory of Advanced Functional Composite Materials Aerospace Research Institute of Materials and Processing Technology Beijing 100076 China

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On the deformation mechanisms of Fe-18Mn-1.3Al-0.6C austenitic steel under unidirectional and cross rolling

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Materials Science and engineering: A 2025年 941卷

作者： Shudong He Liangliang Yin Fulin Jiang Jie Teng Cong He Houguo Lu Honggui Kan Zhuoran Zeng Shiwei Xu College of Materials Science and Engineering Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha 410082 China Anhui Jianghuai Automobile Group Corp Ltd Hefei 230051 China Suzhou Research Institute of Hunan University Suzhou 215131 China

The solution-treated Fe-18Mn-1.3Al-0.6C (wt.%) steel subjected to cross rolling (CR) exhibits higher ductility than the unidirectionally rolled (UR) sample, without sacrificing alloy strength. At 40 % reduction, both CR and UR samples achieve a tensile strength of 1290 MPa, but the uniform elongation of the CR sample reaches 10 %, representing a 30 % increase compared to the UR sample. Microstructural examination reveals that cross rolling effectively promotes twin formation and proliferation, activates additional slip systems, generates twin variants and intersects with each other, and eliminates typical rolling textures, thereby enhancing the TWIP effect and improving ductility. Using X-ray diffraction (XRD)-based modified Williamson-Hall (mWH) and Warren-Averbach (mWA) methods, it is indicated that at higher rolling reductions, the dislocation density in CR samples is significantly higher than in UR samples. This high dislocation density arises from stress concentration zones generated by intersected twins, which act as dislocation sources, along with rapid dislocation proliferation and storage due to dense twin boundaries that have pinned dislocations. Quantitative evaluations of plastic lattice strain and lattice anisotropy show that the cross rolling process induces lower plastic lattice strain and the lattice anisotropy decreases with increasing cross rolling reduction. This observation justifies the higher strain hardening rate and weakened rolling texture in CR samples. The experimental observations and quantitative analysis suggest that the combined effects of an enhanced twinning-induced plasticity (TWIP) effect but lower plastic lattice strain contribute to the superior strength-ductility synergy achieved through cross rolling.

关键词： Manganese steel

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A double-layered nonlinear model predictive control based control algorithm for local trajectory planning for automated trucks under uncertain road adhesion coefficient conditions

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Frontiers of Information technology & Electronic engineering 2020年第7期21卷 1059-1073页

作者： Hong-chao WANG Wei-wei ZHANG Xun-cheng WU Hao-tian CAO Qiao-ming GAO Su-yun LUO College of Mechanical and Automotive Engineering Shanghai University of Engineering ScienceShanghai 201620China State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body Hunan UniversityChangsha 410082China College of Automobile and Transportation Guangxi University of Science and TechnologyLiuzhou 545006China

We present a double-layered control algorithm to plan the local trajectory for automated trucks equipped with four hub motors. The main layer of the proposed control algorithm consists of a main layer nonlinear model predictive control(MLN-MPC) controller and a secondary layer nonlinear MPC(SLN-MPC) controller. The MLN-MPC controller is applied to plan a dynamically feasible trajectory, and the SLN-MPC controller is designed to limit the longitudinal slip of wheels within a stable zone to avoid the tire excessively slipping during traction. Overall, this is a closed-loop control system. Under the off-line co-simulation environments of AMESim, Simulink, dSPACE, and TruckSim, a dynamically feasible trajectory with collision avoidance operation can be generated using the proposed method, and the longitudinal wheel slip can be constrained within a stable zone so that the driving safety of the truck can be ensured under uncertain road surface conditions. In addition, the stability and robustness of the method are verified by adding a driver model to evaluate the application in the real world. Furthermore, simulation results show that there is lower computational cost compared with the conventional PID-based control method.

关键词： Automated truck Trajectory planning Nonlinear model predictive control Longitudinal slip

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Dual-Polarization Second-Order Photonic Topological Insulators

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Physical Review Applied 2021年第3期15卷 034053-034053页

作者： Yafeng Chen Fei Meng Zhihao Lan Baohua Jia Xiaodong Huang Key Laboratory of Advanced Technology for Vehicle Body Design and Manufacture Hunan University Changsha 410082 China Department of Mechanical Engineering Hong Kong Polytechnic University Hong Kong SAR China Faculty of Science Engineering and Technology Swinburne University of Technology Hawthorn Victoria 3122 Australia Department of Electronic and Electrical Engineering University College London Torrington Place London WC1E 7JE United Kingdom

Second-order photonic topological insulators that host highly localized corner states resilient to defects, are opening alternative routes towards developing fascinating photonic devices. However, the existing works on second-order photonic topological insulators have mainly focused on either transverse-magnetic or transverse-electric modes. In this paper, we propose a dual-polarization topological photonic crystal structure for both transverse magnetic and transverse electric modes through topology optimization. Simple tight-binding lattice models are constructed to reveal the topological features of the optimized photonic crystal structure in a transparent way. The optimized dual-polarization second-order photonic topological insulator hosts four groups of corner states with different profiles and eigenfrequencies for both the transverse-magnetic and transverse-electric modes. Moreover, the robustness of these corner states against defects is explicitly demonstrated. Our results offer opportunities for developing polarization-independent topological photonic devices.

关键词： Photonic crystals Polarization of light Symmetry protected topological states Topological effects in photonic systems Dielectrics Topological materials Finite-element method Tight-binding model

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An atomic insight into role of temperature and stress on acidic corrosion behaviour and mechanical property of polycrystalline Fe-based alloys

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Surfaces and Interfaces 2025年 70卷

作者： Zouxueyin Wang Jia Li Shaohua Xing Bin Liu Yong Zhang Qihong Fang State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha 410082 PR China National Key Laboratory for Marine Corrosion and Protection Luoyang Ship Material Research Institute Qingdao 266237 China State Key Laboratory of Powder Metallurgy Central South University Changsha 410083 PR China Naval Aviation University Qingdao Campus Qingdao 266041 PR China

Fe-based alloys have great potential for applications in the aerospace and nuclear industries due to suitable strength and ductility, and high corrosion resistance. However, the acidic corrosion behaviour of polycrystalline Fe-based alloys has not been resolved at atomic scale. In this work, we investigate the acidic corrosion behaviour and mechanical property in nanocrystalline Fe-based alloys, with a focus on the influence of temperature and stress using reactive molecular dynamics (MD) simulations. Deep-sea corrosion experiments are conducted on low-alloy steel to investigate the effect of stress on the corrosion behavior. The results show that the corrosion process exhibits distinct stages and ultimately reaches a state of dynamic equilibrium involving the destruction and regeneration of a passivation film. The corrosion rate at grain boundaries is higher than that within the grains. Additionally, an increase in temperature promotes the rate of metal dissolution, diffusion, and corrosion reactions. The high stress exacerbates corrosion and leads to the formation of more complex corrosion products. The large deformation inhibits the worsening of corrosion. More importantly, corrosion has a significant impact on the yield strength and elastic modulus of Fe-based alloys, reducing their mechanical properties, especially at the elevated temperatures. Deep-sea corrosion experiments reveal the increasing pressure reduces both corrosion rate and pitting depth, while promoting more numerous but shallower pits at higher stresses. The corrosion products align with simulation results, though structural disorder weakens protective capacity. This work affords an atomic insight into the acidic corrosion behaviour and its mechanism origin, which can deepen the fundamental understanding in corrosion processes at the atomic level.

关键词： Corrosion Damage mechanism Fe-based alloys Reactive molecular dynamic simulation

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Cut-cell Cartesian meshes for incompressible laminar and turbulent flows based on n-sided Cell-based Smoothed FEM

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engineering Analysis with Boundary Elements 2025年 178卷

作者： Jiang, Chen Hong, Chen Zhou, Guo Song, Zhi-yang Liu, Ming-yang The State Key Laboratory of Heavy-duty and Express High-power Electric Locomotive Central South University Changsha410075 China Key Laboratory of Traffic Safety on Track of Ministry of Education School of Traffic & Transportation Engineering Central South University Changsha410075 China National & Local Joint Engineering Research Center of Safety Technology for Rail Vehicle Central South University Changsha410075 China Key Laboratory of Railway Industry of Aerodynamics Central South University Changsha410075 China College of Mechanical and Vehicle Engineering Hunan University Hunan Changsha410082 China State Key Laboratory of Mechanical Transmission for Advanced Equipment College of Mechanical Engineering Chongqing University Chongqing400044 China

The cut-cell Cartesian mesh is widely favored in Computational Fluid Dynamics (CFD) due to its ease of generation, body fitting and high quality. However, the presence of hanging nodes and irregular body-fitted polygonal elements makes it challenging to construct shape functions in traditional Finite Element Methods (FEM). In this work, the n-sided Cell-based Smoothed Finite Element Method (nCS-FEM) is developed, introducing detailed construction techniques of smoothed domains in various cut-cell Cartesian meshes and solving incompressible laminar and turbulent flows. The Streamline-Upwind/Petrov–Galerkin stabilization, combined with the Stabilized Pressure Gradient Projection (SUPG/SPGP) method, is employed to mitigate convection and pressure oscillations in nCS-FEM when solving the Unsteady Reynolds–Averaged Navier–Stokes (URANS) equations. Several numerical examples—including analytical solutions for laminar flows and benchmark results from aerospace applications—are presented to validate the applicability and accuracy of the nCS-FEM in solving problems with cut-cell Cartesian meshes (nCS-FEM-Cart). The results demonstrate excellent performance in predicting flow characteristics. Compared to Q4 elements, cut-cell elements facilitate the generation of variable-density meshes, thereby enabling faster computations. Furthermore, a complex structure, i.e. multistage Tesla valves, is employed to evaluate the capability of the realizable k-Ε model in simulating the flow separation and forced convection, highlighting its significant potential in complex engineering problems. © 2025 Elsevier Ltd

关键词： Laminar flow

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Anomalously low thermal conductivity of two-dimensional GaP monolayers: A comparative study of the group GaX (X = N, P, As)

arXiv

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arXiv 2021年

作者： Shen, Chen Hadaeghi, Niloofar Singh, Harish K. Long, Teng Fan, Ling Qin, Guangzhao Zhang, Hongbin Institut für Materialwissenschaft Technische Universität Darmstadt Darmstadt64287 Germany Institute of Applied Materials Karlsruhe Institute of Technology Karlsruhe76131 Germany State Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China

With the successful synthesis of the two-dimensional (2D) gallium nitride (GaN) in a planar honeycomb structure, the phonon transport properties of 2D GaN have been reported. However, it remains unclear for the thermal transport in Ga-based materials by substituting N to other elements in the same main group, which is of more broad applications. In this paper, based on first-principles calculations, we performed a comprehensive study on the phonon transport properties of 2D GaX (X = N, P, and As) with planar or buckled honeycomb structures. The thermal conductivity of GaP (1.52 Wm−1K−1) is found unexpectedly ultra-low, which is in sharp contrast to GaN and GaAs despite their similar honeycomb geometry structure. Based on PJTE theory, GaP and GaAs stabilize in buckling structure, different from the planar structure of GaN. Compared to GaN and GaAs, strong phonon-phonon scattering is found in GaP due to the strongest phonon anharmonicity. Given electronic structures, deep insight is gained into the phonon transport that the delocalization of electrons in GaP is restricted due to the buckling structure. Thus, non-bonding lone pair electrons of P atoms induce nonlinear electrostatic forces upon thermal agitation, leading to increased phonon anharmonicity in the lattice, thus reducing thermal conductivity. Our study offers a fundamental understanding of phonon transport in GaX monolayers with honeycomb structure, which will enrich future studies of nanoscale phonon transport in 2D materials. Copyright © 2021, The Authors. All rights reserved.

关键词： III-V semiconductors

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Projection micro stereolithography based 3D printing and its applications

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International Journal of Extreme Manufacturing 2020年第2期2卷 68-86页

作者： Qi Ge Zhiqin Li Zhaolong Wang Kavin Kowsari Wang Zhang Xiangnan He Jianlin Zhou Nicholas X Fang Department of Mechanical and Energy Engineering Southern University of Science and TechnologyShenzhen 518055GuangdongPeople’s Republic of China BMF Material Technology Inc. Shenzhen 518110ShenzhenPeople’s Republic of China State-Key Laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle EngineeringHunan UniversityChangsha 410082HunanPeople’s Republic of China Department of Mechanical Engineering Massachusetts Institute of TechnologyCambridgeMA 02139-4307United States of America Digital Manufacturing and Design Centre Singapore University of Technology and Design487372Singapore

Projection micro stereolithography(PμSL)is a high-resolution(up to 0.6μm)3D printing technology based on area projection triggered photopolymerization,and capable of fabricating complex 3D architectures covering multiple scales and with multiple *** paper reviews the recent development of the PμSL based 3D printing technologies,together with the related *** introduces the working principle,the commercialized products,and the recent multiscale,multimaterial printing capability of PμSL as well as some functional photopolymers that are suitable to Pμ*** review paper also summarizes a few typical applications of PμSL including mechanical metamaterials,optical components,4D printing,bioinspired materials and biomedical applications,and offers perspectives on the directions of the further development of PμSL based 3D printing technology.

关键词： projection microstereolithography multiscale 3D printing multimaterial 3D printing

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Modeling hetero-deformation induced stress partitioning revealing non-basal slip activity in bimodal-grained ZK60 Mg alloy

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Journal of Magnesium and Alloys 2025年

作者： Mei Zhang Liping Zhong Wenjing Ju Mingshuai Huo Wenzhen Xia Yun Zhang Zhuoran Zeng Qingyu Shi Yongjian Wang Mengran Zhou Institute of Microstructure and Micro/Nanomechanics School of Metallurgical Engineering Anhui University of Technology Maanshan 243002 China School of Materials Science and Engineering Anhui University of Technology Maanshan 243002 China College of Materials Science and Engineering Hunan University Changsha 410082 China State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle Hunan University Changsha 410082 China State Key Laboratory of Clean and Efficient Turbomachinery Power Equipment Department of Mechanical Engineering Tsinghua University Beijing 100084 China Key Laboratory for Advanced Materials Processing Technology Ministry of Education Beijing 100084 China

The excellent strength-ductility combination of hetero-grained Mg alloys has been reported to stem from pronounced hetero-deformation induced (HDI) stress. This stress alters the internal stress state of various slip systems and triggers significant activity of non-basal slips. However, the HDI stress state of different slip systems, and the mechanisms underlying the selective activation between basal and non-basal slips remain unclear to date. This study develops a novel HDI stress partitioning framework that in-situ calculates the crystallographic parameters and geometrical information of each datapoint within grains, aiming to reveal the correlation between HDI stress partitioning on individual slip systems and localized deformation model in the case of bimodal-grained ZK60 alloy. The framework demonstrates that HDI stress shows a strong dependence on the density of geometrically necessary dislocations (GNDs) and slip-system-level grain size, while exhibiting a relatively weaker correlation with equivalent-circle size of the hetero-grains. Given the close relation between the stress partitioning and the physical parameters, the framework can accurately predict the single and multiple slip activity fields obtained from high-resolution digital image correlation (HR-DIC). This holds even for slip systems with low Schmid factors, which are theoretically difficult to activate. Using this framework, it is found that HDI stress plays a more prominent role in diminishing the effective resolved shear stress (RSS) of basal 〈a〉 and prismatic 〈a〉 (i.e., 〈a〉 component) dislocations, while having a negligible effect on pyramidal 〈 c + a 〉 slips. Benefiting from the increased ratio of RSS < c + a > /RSS < a > , pyramidal 〈 c + a 〉 dislocations are extensively activated, leading to excellent strength-ductility combination in the bimodal-grained ZK60 alloy.

关键词： Heterostructure Bimodal-grained ZK60 HDI stress partitioning Strength-ductility synergy Non-basal slip

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Microstructure and properties of selective laser melted Alx CoCrFeNi high entropy alloy via molecular dynamics simulation

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Acta Mechanica Sinica/Lixue Xuebao 2026年第1期42卷

作者： Liu, Jiajun Peng, Jing Li, Weipeng Feng, Hui Peng, Shenyou State Key Laboratory of Advanced Design and Manufacturing Technology for Vehicle College of Mechanical and Vehicle Engineering Hunan University Changsha410082 China China Academy of Safety Science and Technology Beijing100012 China

Selective laser melting (SLM), as an additive manufacturing technology, has garnered widespread attention for its capability to fabricate components with complex geometries and to tailor the microstructure and mechanical properties under specific conditions. However, the intrinsic influence mechanism of microstructure formation under non-equilibrium solidification conditions in SLM processes has not been clearly revealed. In the present work, the influence of Al concentration and process parameters on the microstructure forming mechanism of AlxCoCrFeNi HEAs prepared by SLM is investigated by molecular dynamics simulation method. The simulation results show that the difference in Al content significantly affects the microstructure formation of HEAs, including the growth rate and morphology of columnar crystals, stress distribution at grain boundaries, and defect structure. In addition, the results show that increasing the substrate temperature improves the solidification formability, reduces microstructural defects, and helps reduce residual stress in AlxCoCrFeNi HEAs. By analyzing the influence of heat and solute flow in the molten pool on the growth of columnar crystals, it is found that spatial fluctuations in Al concentration during the non-equilibrium solidification process inhibit the high cooling rates induced by steep temperature gradients. These findings promote the understanding of the forming mechanism of microstructure in HEAs prepared by SLM and provide theoretical guidance for designing high-performance SLM-fabricated HEAs. © The Chinese Society of Theoretical and Applied Mechanics and Springer-Verlag GmbH Germany, part of Springer Nature 2025.

关键词： Crystal microstructure

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