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Zhu S.Y.,Southwest Jiaotong University | Cai C.B.,Southwest Jiaotong University | Luo Z.,China Railway Construction Heavy Industry Co. | Liao Z.Q.,China Railway Longchang Materials Co.
Science China Technological Sciences | Year: 2014

A frequency and amplitude dependent model is used to describe the complex behavior of rail pads. It is implemented into the dynamic analysis of three dimensional coupled vehicle-slab track (3D-CVST) systems. The vehicle is treated as a 35-degree-of-freedom multi-body system, and the slab track is represented by two continuous Bernoulli-Euler beams supported by a series of elastic rectangle plates on a viscoelastic foundation. The rail pad model takes into account the influences of the excitation frequency and of the displacement amplitude through a fractional derivative element, and a nonlinear friction element, respectively. The Grünwald representation of the fractional derivatives is employed to numerically solve the fractional and nonlinear equations of motion of the 3D-CVST system by means of an explicit integration algorithm. A dynamic analysis of the 3D-CVST system exposed to excitations of rail harmonic irregularities is primarily carried out, which reveals the dependence of stiffness and damping on excitation frequency and displacement amplitude. Subsequently, sensitive analyses of the model parameters are investigated by conducting the dynamic analysis of the 3D-CVST system subjected to excitations of welded rail joint irregularities. Following this, parameters of the rail pad model are optimized with respect to experimental values. For elucidation, the 3D-CVST dynamic model incorporated with the rail pads model is used to calculate the wheel/rail forces induced by excitations of measured random track irregularities. Further, the numerical results are compared with experimental data, demonstrating the reliability of the proposed model. © 2014, Science China Press and Springer-Verlag Berlin Heidelberg.

Wang W.-X.,Southwest Jiaotong University | Wang W.-X.,China Railway Construction Heavy Industry Co. | Cai Z.-B.,Southwest Jiaotong University | Qian H.,Shanghai Nuclear Engineering Research and Design Institute | And 5 more authors.
Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals | Year: 2014

Tangential fretting wear characteristics of alloy 690 tubes against 405 stainless steel plates were studied on a fretting wear tester (PLINT TE77) under the dry condition at different temperatures by linear contact. At the test parameters, such as normal load of 40 N, displacement amplitude of 100 μm, frequency of 5 Hz and cycle number of 1×105, the fretting wear test were carried out at 25, 90, 200 and 285℃. The results show that, the fretting condition are all running in gross slip regime. The friction coefficient at 90℃ reaches the highest steady state value, and it occurs a more obvious decrease stage after a period of decline while the temperature increases to 200 and 285℃, which is related with the high-temperature oxidation at the interface. The wear mechanisms are complex with abrasive wear, oxidation wear and delamination. The oxidation of the worn surface at low temperatures (25 and 90℃) is more serious than that at high temperatures (200 and 285℃). The wear volume at 90℃ is higher than that at the other temperatures, this may be related with the water vapor at the interface and the oxide film at the surface. ©, 2014, Zhongguo Youse Jinshu Xuebao/Chinese Journal of Nonferrous Metals. All right reserved.

Zhang J.,China Railway Construction Heavy Industry Co. | Zhang Y.,Nanchang University
Advanced Materials Research | Year: 2014

In this paper, a nonnegative tri-Matrix factorization (NTMF) algorithm is proposed for underdetermined blind sources separation with the assumption of that the source signals are nonnegative and sparse. By incorporating the regularization and sparse penalty into the cost function, a novel multiplicative update rules is proposed to solve the problem of UBSS based on NTMF. The simulation results are presented to show the validity and competitive performances of the proposed algorithm. © (2014) Trans Tech Publications, Switzerland.

Li D.P.,China Railway Construction Heavy Industry Co. | Hu Y.C.,Hangzhou Dianzi University
Applied Mechanics and Materials | Year: 2013

A mesh partition based explicit integration method for dynamic structure FEA is proposed in this article. With this method, the whole finite element mesh is partitioned into several zones according to the elements' increment feature size, and then variable time increments are applied to the mesh zones for explicit integration while the parameter transfer and interpolation is performed over the interfaces to ensure the continuity. This method has the capability of boost the analysis efficiency without much precision loss to the analysis results of interested zones, which is proven by some 2D analysis examples. © (2013) Trans Tech Publications, Switzerland.

Xia Y.,Central South University | Yang D.,Central South University | Hu C.,Central South University | Wu C.,Central South University | Han J.,China Railway Construction Heavy Industry Co.
Tunnelling and Underground Space Technology | Year: 2016

In order to study the characteristics of the ventilation and dust suppression system for open-type TBM tunneling work area in a Ø8.53 diversion project, the numerical simulation method is adopted, and a three-dimensional steady airflow model, a dust flow model as well as other related flow characteristic equation models are established by considering the dust production mechanism of TBM construction. Besides, corresponding simulation models validated by experiment are established using CFD software, and the impacts of the main vent location, the air baffle length in the main beam and the exhausting air flow quantity on flow field distribution and dust flow behavior in open-type TBM tunneling work area are investigated. The results show: when the main vent is located 70-80 m away from the working face, the ventilation in TBM tunneling work area is optimal; when the air baffle is as long as the main beam, the dust collection efficiency is the highest, reaching 89.4%; under the condition that the exhausting air flow quantity is less than half of the ventilation air flow quantity required by energy consumption and the minimum backflow velocity, the best dust suppression effect can be achieved when the exhausting air flow quantity is 40% of the ventilation air flow quantity. © 2016 Elsevier Ltd.

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