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排序方式： 共有1325条查询结果，搜索用时 15 毫秒
221.
Ingo Kaiser Gerhard Poll Gerhard Voss Jordi Vinolas 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2019,57(4):564-594
The hunting motion of a passenger coach is investigated using a multibody system in which the wheelsets and the rails can be modelled as flexible bodies. By comparing the results for different model variants, in which the structural flexibilities of the wheelsets and of the rails are either taken into account or neglected, the impact of the flexibilities is analysed. It turns out that the flexibilities of both the wheelsets and the rails have a significant impact on the hunting behaviour by increasing the lateral motions of the wheelsets and lowering the critical speed. In order to investigate the impact of the flexibilities under different operating conditions, the calculations are carried out for track geometries using different rail profiles (60E1, 60E2) and different rail cants (1:40, 1:20) and for different values for the friction coefficient (0.25…0.4) at the wheel–rail contact. The results show that the influence of the flexibilities is the strongest for high lateral forces, which occur e.g. for contact geometries leading to high hunting frequencies and for high values of the friction coefficient. The results also show in some cases a strong impact of the flexibilities on the position of the wheel–rail contact on the running surface of the rail, which is of particular interest with respect to wear simulation. 相似文献
222.
The increase of public attention, scientific research and political interest in environmental problems associated with transportation has provided the motivation for re-invention of electric vehicles. However the usage of grid-dependent EVs with a high-carbon electricity grid might produce more damage to the environment. This study aims to provide an environmental impact comparison of ICEVs, HEVs and EVs during their usage cycle, by modeling their energy consumption (electricity or fuel) and the supply chains of the supplied energy, (well-to-wheel) based on a life cycle assessment. The results show that running EVs with the existing mixed sources of electrical energy produce larger impacts on the environment 60% of the time; when compared to HEVs. When compared to ICEVs, EVs produce a larger environmental impact on 7 out of 15 environmental impact categories. Overall the environmental impacts of EVs are substantial based on the well-to-wheel analysis. It will continue to be so if no change is made to the methods of electricity generation in the near future. Given that the environmental profile of EVs is linked with the existing national electricity generation mix, the national electricity supply must be made cleaner before the electrification of the urban transport system. 相似文献
223.
Ulrich Spangenberg Robert Desmond Fröhling Pieter Schalk Els 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(5):638-652
The influence of wheel and rail profile shape features on the initiation of rolling contact fatigue (RCF) cracks is evaluated based on the results of multi-body vehicle dynamics simulations. The damage index and surface fatigue index are used as two damage parameters to assess the influence of the different features. The damage parameters showed good agreement to one another and to in-field observations. The wheel and rail profile shape features showed a correlation to the predicted RCF damage. The RCF damage proved to be most sensitive to the position of hollow wear and thus bogie tracking. RCF initiation and crack growth can be reduced by eliminating unwanted shape features through maintenance and design and by improving bogie tracking. 相似文献
224.
L. Xin V.L. Markine I.Y. Shevtsov 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2016,54(3):301-327
A three-dimensional (3-D) explicit dynamic finite element (FE) model is developed to simulate the impact of the wheel on the crossing nose. The model consists of a wheel set moving over the turnout crossing. Realistic wheel, wing rail and crossing geometries have been used in the model. Using this model the dynamic responses of the system such as the contact forces between the wheel and the crossing, crossing nose displacements and accelerations, stresses in rail material as well as in sleepers and ballast can be obtained. Detailed analysis of the wheel set and crossing interaction using the local contact stress state in the rail is possible as well, which provides a good basis for prediction of the long-term behaviour of the crossing (fatigue analysis). In order to tune and validate the FE model field measurements conducted on several turnouts in the railway network in the Netherlands are used here. The parametric study including variations of the crossing nose geometries performed here demonstrates the capabilities of the developed model. The results of the validation and parametric study are presented and discussed. 相似文献
225.
226.
汽车用起动机电枢轴上的螺旋花键,已多采用冷滚轧加工的多键渐开线螺旋花键来代替铣削加工的四键或六键的矩形花键。阐述了渐开线螺旋键冷忆使用的新轧轮的特点及应用;指明了渐开线螺旋花键轴几何尺寸设计时应注意的问题。 相似文献
227.
汽车的操纵稳定性是衡量汽车安全性最基本的指标之一,影响汽车行驶稳定性的基本因素主要有横摆角速度与质心侧偏角,将汽车简化为二自由度模型,建立关于横摆角速度与质心侧偏角的转向微分方程.基于MATLAB/Simulink软件建立仿真模型,对前轮转向与四轮转向典型的二自由度汽车模型进行仿真分析.对比两轮转向和四轮转向的稳定性.... 相似文献
228.
基于前轮转角约束自适应模型预测控制的路径跟踪研究 总被引：1，自引：0，他引：1
针对在车辆行驶中较小的前轮转角无法充分利用路面附着能力,较大的前轮转角使得车辆的行驶稳定性差的问题,文章提出了一种前轮转角约束自适应模型预测方法。首先建立车辆的动力学模型,然后通过计算得到轮胎纵向力,最终得到车辆的前轮转角。将车辆的状态量与前轮转角自适应约束条件输入给模型预测控制器,输出车辆的前轮转角,实现对参考路径的跟踪。在Carsim和MATLAB平台上联合仿真,仿真结果表明前轮转角约束自适应模型预测控制的车辆相比固定转角约束的车辆具有较好的跟踪能力和稳定性。 相似文献
229.
D. H. Koo J. C. Kim W. H. Yoo T. W. Park 《Transportation Research Part D: Transport and Environment》2002,7(6):429-439
Wheel/rail interaction is a major source of railway noise. A low-noise wheel structure is developed and its effect on noise reduction is investigated. This low-noise wheel employs a rubber material inserted into the steel rim or mounted on the wheel surface. The low-noise wheel has low stiffness and a high-damping ratio compared to a solid wheel. Measurement shows that it reduces rolling and squealing. It turns out that a subway line with the proposed wheel could reduce its interior noise level by 4–5 dB(A) and vehicle vibration level by 7–8 dB. While the proposed structure seems promising in noise reduction for railway vehicles, the endurance and cost effectiveness of the low-noise wheel are yet to be verified. 相似文献
230.
N. Bosso N. Zampieri 《Vehicle System Dynamics: International Journal of Vehicle Mechanics and Mobility》2013,51(4):517-541
Traction control is a very important aspect in railway vehicle dynamics. Its optimisation allows improvement of the performance of a locomotive by working close to the limit of adhesion. On the other hand, in case the adhesion limit is surpassed, the wheels are subjected to heavy wear and there is also a big risk that vibrations in the traction occur. Similar considerations can be made in the case of braking. The development and optimisation of a traction/braking control algorithm is a complex activity, because it is usually performed on a real vehicle on the track, where many uncertainties are present due to environmental conditions and vehicle characteristics. This work shows the use of a scaled roller rig to develop and optimise a traction control algorithm on a single wheelset. Measurements performed on the wheelset are used to estimate the optimal adhesion forces by means of a wheel/rail contact algorithm executed in real time. This allows application of the optimal adhesion force. 相似文献