China Railway Construction Heavy Industry Co.
China Railway Construction Heavy Industry Co.
Xia Y.-M.,Central South University |
Wu C.-Z.,Central South University |
Tian Z.-Y.,China Railway Construction Heavy Industry Co. |
Zhao H.-C.,Central South University
Dongbei Daxue Xuebao/Journal of Northeastern University | Year: 2017
In order to study the cutting load characteristics of cutters on the pre-cutting machine in the grooving process, a load calculation model of a single cutter's horizontal cutting was established and its rock-cutting process was simulated using LS-DYNA to analyze the influence of different cutting depths as well as varied blade angles on the horizontal load. The results showed that the horizontal cutting load is much greater than the vertical cutting load, and the horizontal load increases as the cutting depth increases. In condition of the same cutting depth, the horizontal load increases with the increment of blade angles, and it was found that when the blade angle increases from 80° to 125°, the average magnitude of horizontal load at different depths increases by 30.7%. Generally, with the increment of the cutter's blade angle, the specific energy increases firstly and then remains stable. The rock-cutting efficiency reaches its maximum status when the blade angle is 110°, and the specific energy decreases with the increment of cutting depths. © 2017, Editorial Department of Journal of Northeastern University. All right reserved.
Tan Q.,Central South University |
Xie L.,China Railway Construction Heavy Industry Co. |
Xia Y.,Central South University |
Ouyang T.,China Railway Construction Heavy Industry Co. |
And 2 more authors.
Modern Tunnelling Technology | Year: 2016
By studying the contact force and relative velocity of a TBM disc cutter during rock breaking, this paper establishes an analytical model for the friction heat induced by cutter rolling and a finite element model of the disc cutter by combining the finite element method and heat transfer analysis theory, by which a transient simulation of the temperature field is achieved and its distribution at each moment is obtained, as well as the curves of node temperatures and influences of various parameters on cutter temperatures. The results show that: 1) temperatures increase with an increase of distance away from the disc cutter axis in the radial direction, and the temperatures are the same at the points with the same distance away from the disc cutter axis in the radial direction; 2) temperatures increase with a decrease of distance to the central plane of the cutter in the axial direction; 3) temperatures are almost the same with a small gradient in the circumferential direction; 4) disc cutter temperatures will increase and be dynamically stable with an increase of cutting time under a certain working condition, and the increase rate will slow down until it becomes zero; 5) disc cutter temperatures will increase with an increase of the penetration and rotation rate and have a linear relationship to the installation radius of the cutter; and 6) disc cutter temperatures will increase with an increase of rock strength. © 2016, Editorial Office of "Modern Tunnelling Technology". All right reserved.
Yang M.,Southwest Jiaotong University |
Li Y.,Southwest Jiaotong University |
Mai R.,Southwest Jiaotong University |
He Z.,Southwest Jiaotong University |
Wang B.,China Railway Construction Heavy Industry Co.
Conference Proceedings - IEEE Applied Power Electronics Conference and Exposition - APEC | Year: 2017
Inductive Power Transfer has long been considered as an advanced traction power supply technology for Electric Rail Transits. Primary coils are often segmented to reduce resistive power loss. When switching between segments, the secondary pick-up voltage may be vulnerable to large fluctuations because of mutual inductance variation and poor timing of switching actions. In this paper, a method for designing proper distance between adjacent primary coils is introduced for steadier pick-up voltage. A switching scheme and its timing for the LCL circuits is also introduced for stable segment transitioning. FEA simulation and an experimental setup were established. Both simulation and experimental results show that the output voltage remains almost unchanging with the introduced method and validate its feasibility. © 2017 IEEE.
Cheng Y.,Central South University |
Cheng Y.,China Railway Construction Heavy Industry Co.
Zhongnan Daxue Xuebao (Ziran Kexue Ban)/Journal of Central South University (Science and Technology) | Year: 2017
In order to study the rock fragmentation efficiency of TBM disc cutters and its optimal penetration, the finite elements theory was used and the extended Drucker-Prager nonlinear constitutive model was adopted as the rock constitutive model. Considering the damage failure criteria which includes deleting function unit, the process of double disc cutters' rock fragmentation was simulated in three-dimensional dynamic way to study the interaction between rocks and cutters. And the rotary cutting test bench was used to perform the experiment of double disc cutters' rock fragmentation to verify the rationality of the simulation results. The results show that at the penetration of 2.0 mm, the cutting forces of two disc cutters are almost the same. At the penetration of 10.0 mm, the cutting force of the first disc cutter is larger than that of the second disc cutter. Under certain stratum, there is an optimal penetration to make the specific energy consumption the lowest. At the penetration of 4.3 mm, rock cracks can interact with each other and complete fragments can be formed. At the same time, the specific energy consumption is the least. When the penetration is less than 4.3 mm, the cracks cannot intersect through the rocks and rock ridge is formed. When the penetration is larger than 4.3 mm, the rock is broken excessively. © 2017, Central South University Press. 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.
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.
Zhang J.,China Railway Construction Heavy Industry Co.
Advanced Materials Research | Year: 2014
This paper deals with contact to carry on tension, bend, impact toughness's stretch and the inclined Y type ascent experiments of the Hardox400 high strength steel's welding. It research weld, fusion zone and heat affected zone's micro organization of Hardox400 high strength steel in making use of the optical microscope, and prepare hot temperature, weld hot importation and empress hot temperature influence weld strength, bend and impact toughness, and the weld craft parameter can be assured under physically produces condition. © (2014) Trans Tech Publications, Switzerland.
Liu G.-W.,Central South University |
Xia X.,China Railway Construction Heavy Industry Co. |
Wang Q.-Y.,Central South University |
Dong R.-L.,China Communications Construction Company Ltd.
Jiaotong Yunshu Gongcheng Xuebao/Journal of Traffic and Transportation Engineering | Year: 2015
Based on considering the influence of cutting heat, the inertia effects of cutting energy absorption were studied by numerical simulation, and stable cutting force, cutting displacement, maximum temperature, heat dissipative energy and the dissipative proportion of thermal energy were computed under different initial impact conditions. Computation result shows when the initial impact energy is 20 kJ and there are no distinct initial cutting force peaks in chip formation, the stable cutting force ranges from 63.0 kN to 63.8 kN, and the changing rules and trends of cutting force curves are approximately same. When the impact mass is 200 kg and the impact velocity changes from 3 m·s-1 to 10 m·s-1, the stable cutting force ranges from 63.0 kN to 64.4 kN. When the impact velocity is 10 m·s-1 and the impact mass changes from 0.4 t to 3.2 t, the heat dissipative energy increases from 4.12 kJ to 36.64 kJ, the maximum temperature changes between 586℃ and 602℃, the dissipative proportion of thermal energy ranges from 20.6% to 23.2%, and the stable force ranges from 63.0 kN to 64.1 kN. Obviously, when the cutting depth and the geometrical parameters of cutting tool are defined, the initial impact energy, impact mass and impact velocity have little effect on the cutting force, the inertia effects of cutting energy-absorbing process are insensitive, and the cutting energy-absorbing structure belongs to typeI. The cutting heat accounts for a large proportion of energy dissipation and is greatly influenced by the initial impact velocity. ©, 2015, Chang'an University. All right reserved.
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.