Papers by Author: Xi Jun Liu

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Authors: Xi Jun Liu, Xiao Qin Sun, Su Xia Zhang, Peng Liu, Bing Liu
Abstract: Considering strongly nonlinear characteristic of iced conductor rotating around its center of mass in the wind-deviation plane, two dynamic equations are constructed by using Den. Hartog criterion and O. Nigol criterion, and galloping characteristics between them are studied, which can provide references for constructing correct iced conductor galloping models. By comparative analysis of two models, the vibration frequency of O. Nigol model is slightly higher than that of Den. Hartog model, and the amplitude of O. Nigol model is smaller. Then the stability of iced conductor galloping and the effects of parameters on galloping amplitude are discussed, from which can conclude that the trends of two models varying with parameters are basically identical. But for numerical, O. Nigol model is more accurate.
Authors: Xi Jun Liu, Er Hui Zhang, Su Xia Zhang
Abstract: In this paper, the comparative study of RWIV will be proceeding. Aim at the model of rivulet, a kind of sine function is accepted, and another kind of rivulet model is established on the basis of analysis on the stress of the rivulet. Aim at the model of cable’s initial curve under gravity, a kind of parabolic function is accepted, and another kind of model accepted as a catenary. Then, solve the equations of cable and the rivulet jointly by numerical method, get the characteristics of motion of the cable and rivulet, then investigate the factors which is related with the model. The influence of the different model of cable is very little when the rivulet model is assumed as a sine function. However, the influence of the different model of cable is large when the rivulet model is established on the basis of analysis on the stress. Then discover the catenary cable with moving rivulet is more rational with the field observation.
Authors: Xi Jun Liu, Su Xia Zhang, Long Xu Xu, Shu Jun Hou, Bing Huo
Abstract: in this paper, super low noise mining system is analyzed with dynamics model, every constructional element is studied with analysis of kinematics and dynamics, the path of the mass center, angular velocity and angular acceleration of every constructional element is obtained. Nonlinear vibration differential equations of the system are obtained according to Alembert principle. Through numerical analysis, the enforced situation and dynamo load torque of the joint between every constructional element is gained, the influence of crank angle on system response is acquired, and the result has a certain reference value to optimization of the system.
Authors: Jun Yan Cai, Xi Jun Liu, Su Xia Zhang
Abstract: In order to attain the purpose of anti-galloping, a simplified model for iced quad bundle conductors of three degrees of freedom in vertical, horizontal and torsional directions is established by means of the Hamilton principle, in which the effect of spacers stiffness and damping is considered. Based on the model, the influence of related parameters such as fluid density, damping ratio on conductor galloping amplitude and critical wind velocity is analyzed. Simultaneously, the relation curve between elastic property of spacers and conductor galloping is obtained. The results indicate that the conductor galloping can be weakened to some degree with the proper enlargement of damping ratio, the reasonable setting of spring stiffness on spacers and the avoidance of areas such as the wind outlet and windward as much as possible when choosing the line path and so on.
Authors: Xi Jun Liu, Xiao Qin Yuan, Su Xia Zhang
Abstract: MR-TMD is a new type of semi-active control device which combines with Tuned Mass Damper (TMD) and a Magnetorheological (MR) Damper. Taking German ICE3 high-speed railway train through 32meters simply supported box girder bridge for example, a dynamical model of Train-Bridge coupling vibration system is established by considering track irregularities. The relations between the bridge vibration and track irregularities with dampers are studied and the effects of vibration control with TMD and MR-TMD on the bridge are comparatively analyzed. The results show that the effects of track irregularities on vertical displacement of the bridge are relatively small, but on vibration acceleration are relatively large. As the train speed increases, the effects of track irregularities on the vibration acceleration is lager. As the track irregularities increase, the accelerations are greater. MR-TMD is able to inhibit vibration of bridge effectively, and has a wider control range and frequency bandwidth.
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