摘要：
The effect of surface nanostructuring on the liquid-phase aluminizing of Ti-6Al-4V alloy is investigated. A composite interaction layer of TiAl3 and Al is formed in samples with a nanostructured surface layer after liquid-phase aluminizing, of which the thickness is significantly larger than that of the coarse-grained samples, due to the enhanced formation of TiAl3 with more dispersed distribution. Fragmentation and migration of the nanostructured surface layer of the matrix during liquid-phase aluminizing is evidenced, which is responsible for the distinct aluminizing microstructure in surface nanostructured samples. (C) 2017 Elsevier B.V. All rights reserved.
会议名称：
2016 International Symposium on Materials Application and Engineering (SMAE 2016)
会议时间：
2016-01-01
会议地点：
Chiang Mai, Thailand
会议主办单位：
[Wu, Yan] Wuhan Polytech Univ, Sch Mech Engn, Wuhan, Peoples R China.^[Xia, Si] China Aerosp Sci & Inoustry Corp, Acad 4, Special Vehicle Techol Ctr, Beijing, Peoples R China.
会议论文集名称：
MATEC Web of Conferences
摘要：
Nanometer scale and micron scale grain growth of polycrystalline AZ31 Magnesium alloy have been comparatively studied by phase field simulation, and the models are established under realistic spatial-temporal scales. The expression of local free energy density function is modified due to the different initial state of grain growth process at nano scale. The term of grain boundary range is to explain the physical backgrounds of the order parameter gradients at grain boundary and the diffusion grain boundary, and it is related to the correct gradient and coupling parameters. The simulated results are compared in nano scale and micron scale, they are also compared with experimental results in the literature, in order to find out the mechanisms for nano-structural evolution. It is shown that the grain boundary range will cover two adjacent grains in nano scale polycrystalline while the range should be a constant big value of about 1.2μm for grains in micron scale. It is found that the grain growth rate at nano scale is slower than that at the micron scale, and these simulated results can be proved by the experimental results in the literature. It is found that the grain size fluctuation is more intensely in nano-sized grains than that in micron-sized grains by the quantitative analysis of the mixed degree of grains size in nano-structure and micron-structure in the models.
摘要：
A novel method for partial eigenstructure assignment of undamped vibration systems using acceleration and displacement output feedback is presented in this paper. It is based on modifications of mass and stiffness that preserve partial eigenstructure. A numerical algorithm for determining the required control gain matrices of acceleration and displacement output feedback, which assign the desired eigenstructure, is developed. This algorithm is easy to implement, and works directly on the second-order system model. More importantly, the algorithm allows the output matrix and the input matrix to be specified beforehand and also leads naturally to a small norm solution of the gain matrices. Finally, some numerical results are presented to demonstrate the effectiveness and accuracy of the proposed algorithm. (C) 2015 Elsevier Ltd. All rights reserved.
作者机构：
[Wu, Yan] School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan, 430000, China;[Zong, Bernie Yaping] Key Laboratory for Anisotropy and Texture of Materials (Ministry of Education), Northeastern University, Shenyang, 110819, China;[Xia, Si] Special Vehicle Technology Center, The fourth Academy of China Aerospace Science and Industry Corp, Wuhan, 430000, China
作者机构：
[Zhai, Jianbo] School of Mechanical Engineering, Wuhan Polytechnic University, Wuhan, China;[夏俊芳; 周勇] College of Engineering, Huazhong Agricultural University, Wuhan, China
通讯机构：
College of Engineering, Huazhong Agricultural University, Wuhan, China
作者：
Liu, M.;Li, J. Y.;Ma, Y.;Yuan, T. Y.;Mei, Q. S.*
期刊：
Surface and Coatings Technology,2016年289:94-100 ISSN：0257-8972
通讯作者：
Mei, Q. S.
作者机构：
[Mei, Q. S.; Liu, M.; Yuan, T. Y.; Ma, Y.] Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Peoples R China.;[Li, J. Y.] Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
通讯机构：
[Mei, Q. S.] W;Wuhan Univ, Sch Power & Mech Engn, Wuhan 430072, Peoples R China.
关键词：
Surface nanocrystallization;Ti6Al4V alloy;Microhardness;Thermal stability;High pressure surface rolling
摘要：
Ti6Al4V alloy was subjected to high pressure surface rolling (HPSR) deformation. Effects of initial microstructure (heat treatments) and HPSR parameter on the formation of surface nanostructure and mechanical property of Ti6Al4V were investigated. A gradient nano-microstructured surface layer was successfully produced on Ti6Al4V after HPSR, of which the thickness increases and the grain size decreases with the increase of HPSR load (F). Microhardness of HPSR samples increased with decreasing depth from the treated surface, and increased with the increase of F. Microstructure of the original sample including the morphology and size of the alpha and beta phases was found to have evident effect on the thickness, grain size and microhardness of the surface deformed layer produced by HPSR. The HPSR sample showed good thermal stability after annealing at 700 degrees C for 1 h. The present results indicated that HPSR can be used as an effective method for controlled" production of gradient surface nano-microstructure on Ti6Al4V alloy with enhanced property. (C) 2016 Elsevier B.V. All rights reserved.
摘要：
Cu/C composites were prepared from Cu and graphite by accumulative roll-bonding (ARB) up to 30 cycles (N) with a 50% thickness reduction per cycle at room temperature. The microstructure and properties of the Cu/C composites were investigated. Results showed that ARB can remarkably decrease the size of graphite and improve the dispersion of graphite in the Cu matrix. Moreover, significant thickness reduction (down to ~ 5 graphene layers) of the graphite was found in the Cu/C composites fabricated by ARB. The microhardness of the Cu/C composites increases with increasing N and is ~ 3.3 times that of pure Cu for N = 30. The electrical conductivity of the Cu/C composites decreases slightly with increasing N, with a minimum of ~ 90% IACS for N = 30. Our study indicated that ARB can be an effective method for fabrication of Cu/C composites from Cu and graphite with a combination of hardness and electrical conductivity better than or as good as that of carbon nanotube or graphene reinforced Cu matrix composites as reported.
期刊：
IOP Conference Series: Materials Science and Engineering,2015年87(1) ISSN：1757-8981
通讯作者：
Li, Y. N.
作者机构：
[Xu, W. M.; Zhang, G. Q.; Li, Y. N.] Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
通讯机构：
[Li, Y. N.] W;Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
会议名称：
Global Conference on Polymer and Composite Materials (PCM)
会议时间：
MAY 16-19, 2015
会议地点：
Beijing, PEOPLES R CHINA
会议主办单位：
[Li, Y. N.;Xu, W. M.;Zhang, G. Q.] Wuhan Polytech Univ, Sch Mech Engn, Wuhan 430023, Peoples R China.
会议论文集名称：
IOP Conference Series-Materials Science and Engineering
摘要：
Commercial zinc oxide nanoparticles were modified by silane coupling agent of KH550 and KH560, respectively. The obtained nanocomposite was characterized by scanning electron microscopy (SEM), Thermogravimetric analyses (TGA) and apparent sedimentation stability (Sapp). Then, nano-ZnO/high-density polyethylene (HDPE) composite films were prepared via melt blending and a hot compression-molding process. The antibacterial testing of the films against E. coli and S. aureus was carried out via plate counting. SEM, TGA and Sapp suggest the modifier of silane changed the surface hydrophilicity and effectively broke the agglomerations of nanoparticles. Antibacterial testing results indicated the antibacterial rate of the films increased with increasing nano-ZnO content. At a low doped content of 0.2 wt%, the types of coupling agent influenced the antibacterial property with that of KH560-modified nano-ZnO/HDPE KH550-modified nano-ZnO/HDPE unmodified nano-ZnO/HDPE films. When the dosage nano-ZnO was over 0.2 wt%, the differences of antibacterial activity resulted by modification was concealed by the strong antibacterial activity with near 100% of the nano- ZnO/HDPE composite films.
摘要：
A new approach for the partial eigenvalue and eigenstructure assignment of undamped vibrating systems is developed. This approach deals with the constant output feedback control with the collocated actuator and sensor configuration, and the output matrix is also considered as a design parameter. It only needs those few eigenpairs to be assigned as well as mass and stiffness matrices of the open-loop vibration system and is easy to implement. In addition, this approach preserves symmetry of the systems. Numerical example demonstrates the effectiveness and accuracy of the proposed approach.
作者机构：
[陈喜娣; 尹荔松] Department of Electromechanical Engineering, Wuyi University, Guangdong, 529030, China;[蔡启舟] State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan, 430074, China;[罗强] Mechanical Engineering Institute, Wuhan Polytechnic University, Wuhan, 430023, China
通讯机构：
[Cai, Q.] S;State Key Laboratory of Material Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan, China
关键词：
acceleration and velocity feedback;partial quadratic eigenvalue assignment;vibrating system;minimum norm;70J50;65F18;93B52
摘要：
The partial quadratic eigenvalue assignment problem (PQEVAP) is to shift a few undesired eigenvalues of a damped vibrating system to suitably chosen locations, while leaving the remaining eigenvalues and corresponding eigenvectors unchanged. In this paper, an algorithm for solving PQEVAPs and the minimum norm PQEVAP (MNPQEVAP) using acceleration and velocity feedback is proposed. It is shown that solving the PQEVAP here is transformed into solving an eigenvalue assignment of a linear system of a much lower order. Furthermore, the MNPQEVAP here can be efficiently solved by a gradient-based unconstrained optimization method with the derived gradient formula. This algorithm works directly on the second-order system model, and requires the knowledge of only the open-loop eigenvalues to be replaced and their corresponding eigenvectors. Lastly, through two numerical examples, the results of solving the MNPQEVAP under two different combined feedback signals, velocity and displacement signals, and acceleration and velocity signals, are compared from two points of view, i.e. the F-norms of their feedback matrices and the active control energy required from the actuators.
作者机构：
[Gartner, Hunter; Almenar, Eva] Michigan State Univ, Sch Packaging, E Lansing, MI 48824 USA.;[Li, Yana] Wuhan Polytech Univ, Mech Engn Coll, Wuhan, Peoples R China.;[Almenar, Eva] Michigan State Univ, 448 Wilson Rd,Room 130,Packaging Bldg, E Lansing, MI 48824 USA.
通讯机构：
[Almenar, Eva] M;Michigan State Univ, 448 Wilson Rd,Room 130,Packaging Bldg, E Lansing, MI 48824 USA.
关键词：
: phase field methods;second phase particles;nanocrystalline structure;grain growth
摘要：
The grain growth of nanocrystalline AZ31 magnesium alloy containing spherical particles with different sizes is simulated by phase field methods. It is shown that the role of pinning effect of the second phase particles during grain growth is interesting. There is a critical particle size to affect the grain growth in nanostructure. If the size of particles is lower than the critical value, the effect of pinning for grain growth will be increased with further decreasing the size. If the size is larger than the critical value, the particles nearly have no pinning effects. The critical value is 200 nm when the content of particles is 10%. It is found that the grain growth exponents in kinetic equation decrease when the sizes of particles increase in nanostructure with the same volume fraction of the particles, and the pinning effect of particles on the grain growth is decreased as well.
