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Nanchang, China

Deng G.-T.,Ningbo University | Deng G.-T.,Jiangling Motors Co. | Wang H.-R.,Ningbo University | Chen D.-N.,Ningbo University
Gongcheng Lixue/Engineering Mechanics | Year: 2014

Tensile split Hopkinson bar (TSHB) tests for QP980CR steel sheet specimens were optimized by using numerical simulation. The static tensile tests on an 810 material test system (MTS) and the dynamic tensile tests on TSHB at different strain rates and temperatures were performed for these specimens. Based on the stress-strain data obtained from static and dynamic tensile tests, J-C type tensile constitutive equation of this material was determined. The effects of specimen scale on the experimental results were also analyzed. Source

Ye H.-F.,Zhejiang University | Hao Z.-Y.,Zhejiang University | Guo L.,Zhejiang University | Jing G.-X.,Zhejiang University | And 2 more authors.
Neiranji Gongcheng/Chinese Internal Combustion Engine Engineering | Year: 2010

Three profiles of unsymmetrical cam in the forms of polydyne (POL), individual section acceleration (ISAC) and POL-ISAC curves were used in the valve cam design for a high speed diesel engine with side-mounted camshaft. Using two-mass kinetic models, displacement and speed curves of these profiles were calculated. Analyzing their fullness coefficient, jerk and max. contact stress between cam and tappet, the final optimized profile was determined. Based on the multi-freedom dynamic model, comparing with the original profile demonstrate the optimized profile has been improved in terms of impact force of valve on its seat, contact stress between cam and tappet, valve acceleration, valve speed and displacement, etc. Source

Zhao X.,Nanchang Hangkong University | Zhao X.,Jiangling Motors Co. | Ke L.,Nanchang Hangkong University | Xu W.,Nanchang Hangkong University | Liu G.,Nanchang Hangkong University
Fuhe Cailiao Xuebao/Acta Materiae Compositae Sinica | Year: 2011

In order to prepare composites with fine grains, uniform microstructure, and improving the mechanics performance significantly, different contents of carbon nanotubes (CNTs) reinforced aluminum matrix composites were prepared by friction stir processing (FSP). The microstructure, tensile properties and morphologies of tensile fracture surface were analyzed. The results show that CNTs are embedded in the aluminum matrix. The grain size is fine in the center of the friction stir zone. CNTs and matrix have a good combination. There are no obvious defects in the composites. CNTs improve the mechanics performance of the matrix. The tensile strength of aluminum matrix increases with the increasing of CNTs contents. The tensile strength reaches to 201 MPa when the volume fraction of CNTs is 7%, which is 2.2 times than that of matrix. The composites show the characteristics of brittle fracture at the macrostructure and plastic fracture at the microstructure. The fracture mechanism dominates by CNTs/Al interface debonding, matrix tearing and reinforced fiber fracturing. Source

Xiao Q.,East China Jiaotong University | Xiao Q.,Southwest University | Xu H.,Jiangling Motors Co. | Huang B.,East China Jiaotong University | Zhang H.,East China Jiaotong University
Zhongguo Tiedao Kexue/China Railway Science | Year: 2014

On the basis of wheel-rail rolling contact theory and by using the method of mixed Lagrangian/Eulerian with nonlinear finite element software ABAQUS, the large-scale finite element model of wheel-rail steady-state rolling contact was established. The creep force and creepage of CRH2 EMU running on CHN60 rail straight line with the lateral displacement of wheelset ranging from 0 to 6 mm were analyzed. Results show that, the maximum resultant force of the longitudinal creep force within wheel contact patch is 24.4 times of the minimum value with the increase of wheelset lateral displacement. The total longitudinal creep force of train decreases rapidly and almost linearly, which indicates that the traction performance of train will be reduced with the increase of wheelset lateral displacement. The difference between the maximum and minimum resultant force of lateral creep force is about 42.4%, and the change is lower than that of the resultant force of longitudinal creep force. The total lateral creep force of left wheel and right wheel of train decreases with the increase of wheelset lateral displacement, accordingly, both the lateral stability and derailment coefficient of train are affected. The difference between the maximum and minimum longitudinal creepage is 124.8%. Comparing with the longitudinal creepage, the value of lateral creepage is very small and hardly changes with the lateral displacement of wheelset, so the lateral displacement has little effect on the lateral creepage. Source

Xu W.,Nanchang Hangkong University | Ke L.,Nanchang Hangkong University | Xing L.,Nanchang Hangkong University | Zhao X.,Jiangling Motors Co.
Materialwissenschaft und Werkstofftechnik | Year: 2011

The friction stir process (FSP) can be used to prepare carbon nanotubes (CNTs) forming reinforced Al matrix composites. The effect of CNTs content on the wear behaviour and hardness of aluminium based composites was studied. Adding CNTs effectively strengthens the matrix, and significantly improves the hardness of the composites. Composite wear test results showed that the addition of CNTs could enhance the wear resistance of the matrix. With increasing CNTs content, the wear resistance of the matrix markedly improved. The wear curve of the materials is a smooth curve. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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