Theoretical and experimental excitation force spectra for railway-induced ground vibration: vehicle–track–soil interaction,irregularities and soil measurements

Excitation force spectra are necessary for a realistic prediction of railway-induced ground vibration. The excitation forces cause the ground vibration and they are themselves a result of irregularities passed by the train. The methods of the related analyses – the wavenumber integration for the wave propagation in homogeneous or layered soils, the combined finite-element boundary-element method for the vehicle–track–soil interaction – have already been presented and are the base for the advanced topic of this contribution. This contribution determines excitation force spectra of railway traffic by two completely different methods. The forward analysis starts with vehicle, track and soil irregularities, which are taken from literature and axle-box measurements, calculates the vehicle–track interaction and gets theoretical force spectra as the result. The second method is a backward analysis from the measured ground vibration of railway traffic. A calculated or measured transfer function of the soil is used to determine the excitation force spectrum of the train. A number of measurements of different soils and different trains with different speeds are analysed in that way. Forward and backward analysis yield the same approximate force spectra with values around 1 kN for each axle and third of octave.     

山区避险车道设计研究

结合张涿高速设计对山区公路长下坡的避险车道设计进行探讨,提出避险车道对于提高道路安全性能的重要性。     

三峡水库175m蓄水初期库区沿程水位分析

建立一维数学模型,通过三峡库区成库后已取得的实测资料进行验证,计算出三峡水库175～145～155 m正常蓄水运行阶段下特征洪水的沿程水位,对比校核了长江科学院早期计算成果.结果表明:两者在相同计算条件下的水位差值不大,总体基本一致,认为长江科学院早期成果有一定的代表性和指导作用.     

Estimation of road profile variability from measured vehicle responses

When assessing the statistical variability of fatigue loads acting throughout the life of a vehicle, the question of the variability of road roughness naturally arises, as both quantities are strongly related. For car manufacturers, gathering information on the environment in which vehicles evolve is a long and costly but necessary process to adapt their products to durability requirements. In the present paper, a data processing algorithm is proposed in order to estimate the road profiles covered by a given vehicle, from the dynamic responses measured on this vehicle. The algorithm based on Kalman filtering theory aims at solving a so-called inverse problem, in a stochastic framework. It is validated using experimental data obtained from simulations and real measurements. The proposed method is subsequently applied to extract valuable statistical information on road roughness from an existing load characterisation campaign carried out by Renault within one of its markets.     

Speed-independent vibration-based terrain classification for passenger vehicles

Terrain physical characteristics can have a significant impact on passenger vehicle handling, ride quality, and stability. Here, an algorithm is presented to classify terrain using a single suspension-mounted accelerometer. The algorithm passes a measured acceleration signal through a dynamic vehicle model to estimate the terrain profile, and then extracts spatial frequency components of this estimated profile. A method is introduced to identify and remove terrain impulses from the profile that are caused by ruts and potholes. Finally, a supervised support vector machine is employed to classify profile segments as members of pre-defined classes (such as asphalt, brick, gravel, etc.). The classification algorithm is validated with experimental data collected with a passenger vehicle driving in real-world conditions. The algorithm is shown to classify multiple terrain types with reasonable accuracy at a range of typical automotive speeds. It is also shown that the removal of terrain impulses prior to classification improves classifier performance.     

基于虚拟试验场的强化路面建模方法研究

虚拟试验场是依据某汽车试验场建立的,可用于在仿真环境下对车辆进行路试试验。虚拟试验场的路面建模需要保证具有实际路面特性,文章针对虚拟试验场建立中强化路面的建立问题进行研究,提出一种方法,可以准确的建立虚拟试验场的强化路面。利用双轨路面计测量强化路面的不平度,对测试数据进行分析处理,保证测量结果的准确性,应用试验场规则路面的详细尺寸信息建立模拟路面。对于规则强化路面,应用实际尺寸和技术规范等信息建立,对于不规则强化路面,利用实际测量的路面不平度,通过功率谱估计、路面等级分析、路面不平度数字化等建立模拟路面。通过相关性分析,保证所建立的模拟路面的准确性和可信性。     

Road roughness estimation based on discrete Kalman filter with unknown input

ABSTRACT

The road roughness acts as a disturbance input to the vehicle dynamics, and causes undesirable vibrations associated with the ride and handing characteristics. Furthermore, the accurate measurement of road roughness plays a key role in better understanding a vehicle dynamic behaviour and active suspension control systems. However, the direct measurement by laser profilometer or other distance sensors are not trivial due to technical and economic issues. This study proposes a new road roughness estimation method by using the discrete Kalman filter with unknown input (DKF-UI). This algorithm is built on a quarter-car model and uses the measurements of the wheel stroke (suspension deflection), and the acceleration of the sprung mass and unsprung mass. The estimation results are compared to the measurements by laser profilometer in-vehicle test.     

桥面不平顺对下承式系杆拱桥振动影响的试验和模拟研究

为了获得下承式系杆拱桥的汽车荷载冲击系数，在桥面间隔布置橡胶减速条带以形成周期性的不平顺输入，对下承式钢管混凝土系杆拱桥的动挠度进行现场实测。结合自编的车桥耦合（VBI）单元，建立车-桥耦合振动三维有限元分析模型，通过与实测结果对比验证VBI单元的正确性。在此基础上，引入另外3座标准拱桥以形成涵盖4种跨径的下承式系杆拱桥研究对象，输入规范规定的A~D级不平顺，研究车速、车重和桥梁基频对系梁冲击系数的影响。研究结果表明：汽车通过周期间隔布置的减速带时会形成稳态激振，当激振频率接近桥梁的前2阶基频时，引起的系梁动挠度响应最大；系梁的汽车荷载冲击系数随着桥梁基频的增加呈现出先增大后减小的趋势，当小汽车（总重低）行驶于差桥面（D级不平顺）时，规范值明显低估了系梁的冲击系数。     

表面粗糙度对冰路面上滑动轮胎摩擦牵引力影响的研究

依据能量守恒定律和冰的摩擦熔化理论，考虑冰面和轮胎胎面的表面粗糙度，建立了摩擦界面冰完全熔化条件下轮胎的牵引力预测模型。给出了预测模型中接地胎面温度的选择原则。研究表明，该模型可较好地预测不同条件下轮胎在冰路面上的摩擦牵引力，表面粗糙度的影响随车辆行驶速度的提高而增大。     

沥青路面平整度的影响因素

通过对衢窑高速公路沥青路面的实地调查,找出影响沥青路面平整度的各种因素,并通过因果分析提出了相应对策.