独塔斜拉桥钢塔竖转施工计算分析

竖转施工方法可降低索塔结构高空拼装难度,便于结构尺寸精度控制,提高焊接质量和工效,被广泛应用于斜拉桥施工。为分析独塔斜拉桥钢塔竖转施工过程中的受力状态,运用ANSYS软件模拟独塔斜拉桥竖转施工过程,计算钢塔在不同阶段的应力、变形和稳定性。结果表明,转体启动阶段和结束阶段钢塔受力状态最不利,应重点监测。在启动阶段,钢塔的变形较大,应作为主要控制监测指标。     

浅谈华侨新村路商业步行街设计

该文就汕头市华侨新村路商业步行街设计中的诸如立项指导思想、位置选择、功能需求、投资分析以及整体景观等细部设计问题作了论述。     

混合动力汽车多途径节能定量研究

文中分析了动力总成的能量消耗特点及功率流关系,提出了混合动力汽车的4条节能途径,并计算城市客车在典型城市工况下的燃油及能量消耗。分别对各节能途径进行了节能贡献的分析,最后总结了各城市工况下最大的总节能潜力。     

上海长江大桥主桥斜拉桥双箱梁节段的三维空间屈曲

上海长江大桥主通航孔桥斜拉桥的桥面结构为中间箱形联系梁连接的分离式双箱梁钢结构体系,具有十分复杂的空间效应,而局部屈曲问题是钢箱梁设计中的一个关键问题。因此,对双箱梁节段的局部屈曲分析是非常有必要的。运用大型结构分析软件SAP2000的三维板壳单元进行建模,模型边界的荷载施加考虑了结构总体分析的真实受力工况,分析得到了一些双箱梁节段的三维屈曲模态及屈曲系数,并且提出了一些对结构设计有价值的建议。     

The effect of wheel set gyroscopic action on the hunting stability of high-speed trains

This study explores the effects of wheel set gyroscopic action on hunting stability by calculating linear and nonlinear critical speeds. First, a dynamic model for a high-speed vehicle with 23 degrees of freedom is developed by considering wheel set gyroscopic action. The linear and nonlinear critical speeds are calculated by eigenvalue analysis and drawing a bifurcation map, respectively. Two computer programs for linear and nonlinear stability analysis are developed. Second, based on an actual high-speed vehicle in China, the effects of wheel set gyroscopic action on hunting stability are quantitatively investigated using computer simulation. Furthermore, the difference between the effects of gyroscopic moments about the x-axis and z-axis is discussed. The results show that the moment about the x-axis is harmful to hunting stability, but the moment about the z-axis is beneficial to hunting stability. However, the integrated effect of these two moments can enhance the critical speeds and suppress the hunting motion.     

Carbody elastic vibrations of high-speed vehicles caused by bogie hunting instability

In particular locations of the high-speed track, the worn wheel profile matched up with the worn rail profile will lead to an extremely high-conicity wheel–rail contact. Consequently, the bogie hunting instability arises, which further results in the so-called carbody shaking phenomenon. In this paper, the carbody elastic vibrations of a high-speed vehicle in service are firstly introduced. Modal tests are conducted to identity the elastic modes of the carbody. The ride comfort and running safety indices for the tested vehicle are evaluated. The rigid–flexible coupling dynamic model for the high-speed passenger car is then developed by using the FE and MBS coupling approach. The rail profiles in those particular locations are measured and further integrated into the simulation model to reproduce the bogie hunting and carbody elastic vibrations. The effects of wheel and rail wear on the vehicle system response, e.g. wheelset bifurcation graph and carbody vibrations, are studied. Two improvement measures, including the wheel profile modification and rail grinding, are proposed to provide possible solutions. It is found that the wheel–rail contact conicity can be lowered by decreasing wheel flange thickness or grinding rail corner, which is expected to improve the bogie hunting stability under worn rail and worn wheel conditions. The carbody elastic vibrations caused by bogie hunting instability can be further restrained.     

基于电机最优回馈转矩曲线的制动控制策略

本文中首先基于电机等效电路模型,分析了车用内置式永磁同步电机的耗能制动状态和回馈制动状态;然后根据电机矢量控制原理,对控制电流指令进行解析,并经试验数据的验证;接着计算得到永磁同步电机最优回馈转矩曲线,并据此提出一种制动回馈能量最优的串联制动控制策略。最后针对某P4并联混合动力商用车,仿真分析了在C?WTVC、CHTC?TT循环工况和试验采集到的某段省道工况下,并联制动和所提出的串联最优制动控制策略下的百公里油耗和制动回收能量。结果表明,与并联制动控制相比,基于电机最优回馈转矩曲线的串联制动控制策略可降低油耗,并回收更多的制动能量,实现制动回收能量和燃油经济性的提升。     

车用锂离子电池相变冷却技术研究综述

从相变材料这一角度,综述了相变材料的选取制备、相变材料新型冷却结构的设计、相变材料与其它冷却方式耦合形成的散热系统3个方面对锂离子电池散热的影响,并总结了翅片辅助相变冷却,泡沫金属辅助相变冷却、相变材料与热管耦合的散热系统的优势与不足.分析结果表明,优化复合相变材料的成分配比,向相变材料中加入翅片或者泡沫金属都有助于散...     

基于ansys的油底壳湿模态研究

本文基于solidworks建立油底壳仿真模型,再将模型导入ansysworkbench软件,然后对油底壳网格无关性验证,然后对其约束干模态分析以及含有机油时湿模态分析,探究机油高度的影响对模态频率的变化情况.仿真实验结果表明在含有机油时随着液体高度的增加油底壳的模态频率大致呈下降的趋势.     

探究居住区停车共享存在问题及对策

文章采用实地观察统计与调查问卷的方法针对重庆市停车共享现状展开调研,针对居住区停车泊位使用特性,对重庆市2处居住区及附近商场开展了5天的停车状况调查,整理数据分析居民区停车共享可行性.文章对重庆市江北区、渝北区、渝中区、南岸区、大渡口区、沙坪坝区共计12个已使用共享停车这种模式的停车场发放问卷调查,从建设运营方、提供车...