车轨桥振动系统垂向模型和空间模型的比较

分别建立了车辆-轨道-桥梁系统的垂向耦合振动模型和空间耦合振动模型,并通过功率普密度得到轨道高低不平顺的时域模拟样本,以其作为激励,分析两种模型下车辆-轨道-桥梁耦合振动系统的振动响应。通过对比相同轨道高低不平顺激励下垂向振动模型和空间振动模型的垂向振动响应计算结果,分析了两种模型的优缺点和适用性。     

Analysis theory of spatial vibration of high-speed train and slab track system

The motor and trailer cars of a high-speed train were modeled as a multi-rigid body system with two suspensions. According to structural characteristic of a slab track, a new spatial vibration model of track segment element of the slab track was put forward. The spatial vibration equation set of the high-speed train and slab track system was then established on the basis of the principle of total potential energy with stationary value in elastic system dynamics and the rule of ＂set-in-right-position＂ for formulating system matrices. The equation set was solved by the Wilson-θ direct integration method. The contents mentioned above constitute the analysis theory of spatial vibration of high-speed train and slab track system. The theory was then verified by the high-speed running experiment carried out on the slab track in the Qinghuangdao-Shenyang passenger transport line. The results show that the calculated results agree well with the measured rcsults, such as the calculated lateral and vertical rail displacements are 0.82 mm and 0.9 mm and the measured ones 0.75 mm and 0.93 mm, respectively; the calculated lateral and vertical wheel-rail forces are 8.9 kN and 102.3 kN and the measured ones 8.6 kN and 80.2 kN, respectively. The interpolation method, that is, the lateral finite strip and slab segment element, for slab deformation proposed is of simplification and applicability compared with the traditional plate element method. All of these demonstrate the reliability of the theory proposed.     

轨道刚度变化对高速列车-板式轨道系统振动响应的影响分析

针对板式轨道的结构特点,利用横向有限条与板段单元模拟板式轨道,并考虑轮轨竖向位移衔接条件,基于弹性系统动力学总势能不变值原理及形成系统矩阵的“对号入座”法则,建立了高速列车-板式轨道动力学耦合系统的竖向振动矩阵方程.在此基础上,分析了板式轨道的刚度变化对此系统竖向振动响应的影响规律.计算结果表明,合理的轨道刚度将有利于降低此系统的竖向振动响应.并建议CA砂浆刚度合理的取值范围为1 000—1 500 MPa/m,轨下垫层刚度合理的取值范围为60—80 kN/mm.     

基于混凝土塑性损伤模型的轨道板损伤规律

基于混凝土塑性损伤模型,建立CRTS Ⅰ型轨道板损伤分布计算模型,将Tekscan传感器测得的钢轨支点压力作为荷载输入,以轨道板竖向位移及拉伸损伤因子作为评价指标,分析客货共线条件下水泥乳化沥青（CA）砂浆离缝状态时锚穴周边轨道板上表面混凝土的内部损伤规律. 结果表明：随着离缝长度的不断扩展,损伤产生及完全损伤的临界离缝高度均逐渐变小;当离缝长度扩展至第2、3锚穴时,客车荷载下损伤产生的临界离缝高度分别约为0.8、1.0 mm,货车荷载下约为0.5、0.8 mm;一旦超出损伤产生的临界离缝高度,由于轨道板损伤的发展,轨道结构整体抗弯刚度迅速降低导致板端竖向位移迅速增大;对于客车荷载,当离缝扩展至第3锚穴且高度大于1.0 mm后,CA砂浆形成脱空,板端位移不再增长,对于货车荷载,当离缝扩展至第3锚穴且高度大于1.3 mm后,由于二次损伤带的产生,板端竖向位移随离缝高度的增大迅速增大.     

Temperature-induced deformation of CRTS II slab track and its effect on track dynamical properties

Two finite-element models of the CRTS II slab track are presented to simulate temperature-induced deformations of the concrete track slab with no deterioration or with a deteriorated cement asphalt mortar(CAM).One model,which considers the fully bonding interface between the slab and the CAM layer,could applied to a track that is in good condition;the other model uses cohesive zone elements to simulate the deteriorated CAM with some possible interfacial separation and slip.Utilizing both of the models,temperature-induced warp deformations of track under various temperature loads are investigated.The influence of temperature deformation on the dynamic properties of the track is analyzed based on the train-track coupled dynamics.Numerical results show that the deteriorated CAM layer can significantly increase temperature deformations of a CRTS II track slab,which would produce tiny rail irregularities.There are clear differences between the deformation shapes of the track slabs that have an inseparable mortar layer and those have a separable mortar layer.The track slab with a deteriorated mortar layer showed more open curl distortion than the track slab in good condition.The dynamical response index of the slab track is intensified to a certain level due to the temperature deformation;with an increase of the train speed,the track dynamical responses increased linearly.However,rail irregularities due to the temperature deformations are very tiny.Even if a track is exposed to extreme temperature loads and the mortar layer is deteriorated,temperature deformation can have a negligible effect on the track’s dynamical properties.     

一种无碴轨道动力学建模的新方法

针对无碴轨道（以博格板式轨道为例）结构特点，提出横向有限条与板段单元动力分析新模型。将高速列车（以中华之星为例）的动车及拖车均离散为具有二系悬挂的多刚体系统，基于弹性系统动力学总势能不变值原理及形成系统矩阵的“对号入座”法则，建立高速列车-无碴轨道时变系统竖向振动矩阵方程，采用Wilson-θ法求解。分别采用传统的静力模型和横向有限条与板段单元动力分析模型，计算并比较钢轨与博格板的静、动态竖向位移最大值，得出车速为200km／h时此系统竖向振动响应时程曲线。计算结果表明，钢轨与博格板的静、动态竖向位移最大值接近，计算值均在通常值范围内，说明所提出的新模型正确、可行。     

车辆-钢轨-钢弹簧浮置板道床耦合系统振动特性分析

根据分析动力学原理,建立了列车-轨道结构耦合系统模型。采用ANSYS软件对系统进行了模态分析和谐响应分析,得到了系统的固有频率和振型。根据振动理论得到了地基反力和力传递率幅频特性曲线。以Sperling指标为依据,对乘车舒适度进行了评价分析。进一步研究了不同钢弹簧刚度和阻尼情况下,乘车舒适度和地基反力的变化规律。结果表明:钢弹簧刚度越大,乘车舒适性越好,传至地基的反力越大;钢弹簧阻尼越大,乘车舒适性越好,传至地基的反力也越小。     

Damage evolution and dynamic response of cement asphalt mortar layer of slab track under vehicle dynamic load

The damage evolution and dynamic performance of a cement asphalt (CA) mortar layer of slab track subjected to vehicle dynamic load is investigated in this paper. Initially, a statistical damage constitutive model for the CA mortar layer is developed using continuous damage mechanics and probability theory. In this model, the strength of the CA mortar elements is treated as a random variable, which follows the Weibull distribution. The inclusion of strain rate dependence affords considering its influence on the damage development and the transition between viscosity and elasticity. Comparisons with experimental data support the reliability of the model. A three-dimensional finite element (FE) model of a slab track is then created with the commercial software ABAQUS, where the devised model for the CA mortar is implemented as a user-defined material subroutine. Finally, a vertical vehicle model is coupled with the FE model of the slab track, through the wheel-rail contact forces, based on the nonlinear Hertzian contact theory. The evolution of the damage and of the dynamic performance of the CA mortar layer with various initial damage is investigated under the train and track interaction. The analysis indicates that the proposed model is capable of predicting the damage evolution of the CA mortar layer exposed to vehicle dynamic load. The dynamic compressive strain, the strain rate, and the induced damage increase significantly with an increase in the initial damage, whereas the dynamic compressive stress exhibits a sharp decrease with the increasing initial damage. Also, it is found that the strain rate dependence significantly influences the damage evolution and the dynamic behavior of the CA mortar layer.     

叠合式双向板试验与数值模拟对比分析

针对传统双向板与两拼、三拼叠合式双向板用ABAQUS进行有限元非线性模拟分析,对比这三种双向板的挠度、钢筋应变以及裂缝开展等方面差别。结果表明与传统双向板比较这种两拼叠合式双向板在受力性能上基本相同,最后总结两拼叠合式双向板在受力时的状态,并提出改进建议以及还需解决的问题,从而为叠合式剪力墙板结构技术规程的完善提供理论依据,为其能够广泛应用于高层建筑的施工建设提供技术支持和理论支撑。     

实时系统中的连铸板坯边缘检测快速算法

分析了影响边缘检测算法速度的关键因素,针对连铸板坯边缘实时测量问题,提出了一种基于灰度图像投影的边缘检测快速算法,这一算法适用于直线型阶跃边缘的快速检测,并在实际应用中取得了良好的效果。     

连铸板坯内部裂纹的研究分析

通过分析连铸板坯中内部裂纹的形成原因，针对济钢板坯内部裂纹的表现形式和级别，提出了减轻内部裂纹缺陷形成的措施。     

Effect of cross-wind on spatial vibration responses of train and track system

By taking cross-wind forces acting on trains into consideration, a dynamic analysis method of the cross-wind and high-speed train and slab track system was proposed on the basis of the analysis theory of spatial vibration of high-speed train and slab track system. The corresponding computer program was written by FORTRAN language. The dynamic responses of the high-speed train and slab track under cross-wind action were calculated. Meanwhile, the effects of the cross-wind on the dynamic responses of the system were also analyzed. The results show that the cross-wind has a significant influence on the lateral and vertical displacement responses of the car body, load reduction factor and overturning factor. For example, the maximum lateral displacement responses of the car body of the first trailer with and without cross-wind forces are 32.10 and 1.60 mm, respectively. The maximum vertical displacement responses of the car body of the first trailer with and without cross-wind forces are 6.60 and 3.29 mm, respectively. The maximum wheel load reduction factors of the first trailer with and without cross-wind forces are 0.43 and 0.22, respectively. The maximum overturning factors of the first trailer with and without cross-wind forces are 0.28 and 0.08, respectively. The cross-wind affects the derailment factor and lateral Sperling factor of the moving train to a certain extent. However, the lateral and vertical displacement responses of rails with the cross-wind are almost the same as those without the cross-wind. The method presented and the corresponding computer program can be used to calculate the interaction between trains and track in cross-wind. Foundation item: Project (2007CB714706) supported by the Major State Basic Research and Development Program of China; Project (50678176) supported by the National Natural Science Foundation of China; Project (NCET-07-0866) supported by the New Century Excellent Talents in University     

Longitudinal crack on slab surface at straightening stage during continuous casting using finite element method

Deformation behavior of slab at the straightening stage during continuous casting was simulated by the explicit dynamic finite element method, and the stress distribution along the width direction of the slab and its change regularity at slab center during continuous casting were obtained. The influence of distribution and change of stress on the propagation of longitudinal cracks on slab surface was discussed. The results show that the tensional stress appears on slab surface at the inner arc side and the compressive stress appears on slab surface at the outer arc side at stages 6-8 in straightening zone during continuous casting. Longitudinal cracks generally appear on slab top surface and do not appear on slab bottom surface, which are also observed in industry.     

现浇混凝土空心楼板的有限元分析

采用ANSYS有限元软件建立空心楼板模型,对空心楼板进行受力分析,将采用有限元所得剪力与《现浇混凝土空心楼盖结构技术规程》中的剪力计算公式所得剪力比较.结果表明空心楼板的受力性能与一般受弯构件相同,并且《规程》中的剪力计算结果与ANSYS所得结果相近,可以应用在空心板的剪力设计中.     

Heat-transfer model on the improvement of continuous casting slab temperature

A heat transfer model on the solidification process has been established on the basis of the technical conditions of the slab caster in No.3 steel works of Wuhan Iron & Steel Corporation, and the temperature field in the solidifying slab was calculated which was verified by the measured slab surface temperature. The influences of the main operating factors including casting speed, spray cooling patterns, superheat of melt and slab size on the solidification process were analyzed and the means of enhancing the slab temperature was brought forward. Raising the casting speed to 1.3 m/min, controlling the flowrate of secondary cooling water and improving the cooling pattern at the lower segments of secondary cooling zone could improve the slab temperature effectively. And the increasing the superheat is adverse to the production of high temperature slab.     

Effect of cooling structure on thermal behavior of copper plates of slab continuous casting mold

A three-dimensional finite-element model of slab continuous casting mold was conducted to clarify the effect of cooling structure on thermal behavior of copper plates. The results show that temperature distribution of hot surface is mainly governed by cooling structure and heat-transfer conditions. For hot surface centricity, maximum surface temperature promotions are 30℃ and 15℃ with thickness increments of copper plates of 5 mm and nickel layers of 1 mm, respectively. The surface temperature without nickel layers is depressed by 10℃ when the depth increment of water slots is 2 mm and that with nickel layers adjacent to and away from mold outlet is depressed by 7℃ and 5℃, respectively. The specific trend of temperature distribution of transverse sections of copper plates is nearly free of cooling structure, but temperature is changed and its law is similar to the corresponding surface temperature.     

Characteristics of shell thickness in a slab continuous casting mold

The key to reduce shell breakout in the continuous casting process is to control shell thickness in the mold.A numerical simulation on the turbulent flow and heat transfer coupled with solidification in the slab mold using the volume of fluid (VOF) model and the enthalpy-porosity scheme was conducted and the emphasis was put upon the flow effect on the shell thickness profiles in longitudinal and transverse directions.The results show that the jet acts a stronger impingement on the shell of narrow face,which causes a zero-increase of shell thickness in a certain range near the impingement point.The thinnest shell on the slab cross-section locates primarily in the center of the narrow face,and secondly near the comer of the wide face.Nozzle optimization can obviously increase the shell thickness and make it more uniform.     

基础沉降对连续空心板梁拓宽影响研究

选择某9×20 m混凝土连续空心板梁为工程背景,研究连续空心板梁拓宽时新旧地基沉降差对结构受力的影响,利用有限元软件建立模型,分析了地基不均匀沉降对旧桥拓宽影响,分析结果表明：地基不均匀沉降对桥梁拓宽影响较大,应确定地基不均匀沉降的控制值。提出减少不均匀沉降的措施,为施工提供参考。     

连铸坯红送热装应用效果分析

对加热炉用连铸坯红送热装效果的分析结果表明，该技术的应用可节能降耗，提高产量和加热质量。     

Temperature distribution and dynamic control of secondary cooling in slab continuous casting

To predict and optimize the temperature distribution of slab continuous casting in steady operational state, a three-dimensional model (named offline model) based on the heat transfer and solidification theories was developed. Both heat transfer and flux distribution characteristics of the nozzle sprays on the slab were considered, and the complicated boundary condi-tions, such as spray cooling, natural convection, thermal radiation as well as contact cooling of individual rolls were involved in the model. ...