Investigating the influence of soil properties on railway traffic vibration using a numerical model

This paper presents the influence of dynamic and geometrical soil parameters on the propagation of ground vibrations induced by external loads. The proposed approach is based on a three-dimensional model, focusing on realistic excitation sources like impulse loads and moving railway vehicles. For the latter, a complete vehicle/track model is developed. The simulation is performed in time domain, offering an interesting approach, compared with classic cyclic analyses. The ground is modelled initially as an elastic homogeneous half-space and additionally as a layered half-space. First, the effect of homogeneous soil properties on ground vibration is analysed. Soil stratification is then taken into account, using various configurations. Analysis reveals that as receiver distance increases ground wave reflection in a layered ground plays an important role in the reduction of ground surface motion. This effect is magnified when the phase velocity wavelength becomes large compared with the depth of the surface layer.     

A novel fuzzy logic correctional algorithm for traction control systems on uneven low-friction road conditions

The traction control system (TCS) might prevent excessive skid of the driving wheels so as to enhance the driving performance and direction stability of the vehicle. But if driven on an uneven low-friction road, the vehicle body often vibrates severely due to the drastic fluctuations of driving wheels, and then the vehicle comfort might be reduced greatly. The vibrations could be hardly removed with traditional drive-slip control logic of the TCS. In this paper, a novel fuzzy logic controller has been brought forward, in which the vibration signals of the driving wheels are adopted as new controlled variables, and then the engine torque and the active brake pressure might be coordinately re-adjusted besides the basic logic of a traditional TCS. In the proposed controller, an adjustable engine torque and pressure compensation loop are adopted to constrain the drastic vehicle vibration. Thus, the wheel driving slips and the vibration degrees might be adjusted synchronously and effectively. The simulation results and the real vehicle tests validated that the proposed algorithm is effective and adaptable for a complicated uneven low-friction road.     

The effects of wheelset driving system suspension parameters on the re-adhesion performance of locomotives

In this study, in order to examine the effects of a wheelset driving system suspension parameters on the re-adhesion performance of locomotives, the stick–slip vibration was analysed according to theoretical and simulation analysis. The decrease of the slip rate vibration amplitude improved the stability of the stick–slip vibration and the re-adhesion performance of locomotives. Increasing the longitudinal guide stiffness of the wheelset and the motor suspension stiffness were proposed as effective measures to improve the re-adhesion performance of locomotives. These results showed that the dynamic slip rate was inversely proportional to the series result of the square root of the longitudinal guide and motor suspension stiffness. The larger the motor suspension stiffness was, the smaller the required longitudinal guidance stiffness was at the same re-adhesion time once the wheel slip occurred, and vice versa. The simulation results proved that the re-adhesion time of the locomotive was approximately proportional to amplitude of the dynamic slip rate. When the stick–slip vibration occurred, the rotary and the longitudinal vibrations of the wheelset were coupled, which was confirmed by train's field tests.     

关于气动系统在汽车工装夹具上的应用探讨

本文基于汽车车身工装夹具基础内容展开分析,结合气动系统的基础组成和应用特征.通过研究气缸的应用、控制阀应用、气动三联件、管路应用、消声器应用等内容.其目在于明确气动系统的应用要点,为后续应用体系的完善奠定基础.     

刚性悬挂自由振动特性分析

以南京地铁一号线刚性悬挂参数为依据,利用有限元模态分析法建立了接触网刚性悬挂自由振动的振型,列举出自由振动的各阶频率,并从模拟计算结果中分析了刚性悬挂的一些振动特性。     

城市轨道交通环境影响评价中值得注意的问题

通过对近年来国内城市轨道交通环境影响评价实例的回顾,在对环境评价结果与实际效果进行分析和总结的基础上,对环境影响评价中的若干问题进行综合探讨,包括环境保护目标的选择、源强类比的准确性、噪声与振动预测方法及采取控制措施的原则等。     

轨道不平顺对轮对纵向振动影响分析

轮对纵向振动问题是一个长期以来被忽略的内容,研究发现轮对纵向振动虽然对整车的横向稳定性影响不大,但却对整车的垂向动力学性能和轮轨动态作用力有很大的影响。进一步分析发现,剧烈的轮对纵向振动,与轨道的横向和高低不平顺有关。在光滑的轨道上不会发生纵向共振。提出通过改变一系垂向减振器的布置方式可以抑制轮对的大部分纵向振动,减小轮轨动态作用力,延长轮对和钢轨的使用寿命。     

TMD抑制既有铁路钢桁梁桥横向振动研究

针对我国既有铁路钢桁梁桥的振动特性,对机车、转8转向架货车和客车分别建立车桥TMD系统耦合振动方程,将轮对的蛇行及轨面不平顺作为主要的激振源,通过随机函数产生随机激振,利用车桥TMD耦合振动仿真程序的大量模拟计算,研究桥梁在列车尤其是长大空重混编的货物列车随机激励下的横向振动规律,分析多点调频质量阻尼减振器抑制铁路钢桁梁桥横向振动的效果。结果表明,TMD能有效的抑制既有铁路钢桁梁桥的横向振动。     

车辆参数对铁路连续钢桁梁桥竖向有载自振频率的影响

车辆轮对簧下质量、车辆轮对悬挂弹簧刚度、车辆长 度、车体质量等对3×64m铁路连续钢桁梁桥竖向有载自振频 率都有影响,而列车的行车速度对桥梁竖向有载自振频率没有 影响。所得结论与简支梁桥一致。     

KZ4A型交流传动电力机车

KZ4A型交流传动电力机车用于哈萨克斯坦国家铁路干线高速客运。文章介绍了该车的技术特征、总体布局、性能参数及主要部件特点。