Berechnung des extremen Lenk- und Bremsverhaltens von Sattelkraftfahrzeugen

Simulation of Steering and Braking Behaviour of Tractor-Semitrailer Vehicles in Extreme Situations

This paper deals with the simulation of the behaviour of tractor-semitrailer vehicles at braking on wet, slippery road surface. The nonlinear model used for the computation enables to simulate extreme situations at wheel locking and swerving

The instabilities during braking such as jackknifing and trailer swing as well as non steerability are investigated. Straightline braking shows the influence of cornering on the behaviour during braking in a turn.     

Messungen von Fahrbahn-Unebenheiten paralleler Fahrspuren und Anwendung der Ergebnisse

Measurement of two track road inputs and theoretical application of the results

The calculation of vehicle response to road-surface irregularity inputs requires the spectral densities of the left and right longitudinal track and their statistical dependence

This paper presents some resluts of parallel profile measurements, three typical german roads have been chosen

Random vibration of two vehicle types are digital-simulated. The dynamic tire load shows that independent suspension systems are more advantageous than beam axles, because by wheel tramp this type increases the dynamic tire load.     

User-Appropriate Tyre-Modelling for Vehicle Dynamics in Standard and Limit Situations

Summary When modelling vehicles for the vehicle dynamic simulation, special attention must be paid to the modelling of tyre-forces and -torques, according to their dominant influence on the results. This task is not only about sufficiently exact representation of the effective forces but also about user-friendly and practical relevant applicability, especially when the experimental tyre-input-data is incomplete or missing. This text firstly describes the basics of the vehicle dynamic tyre model, conceived to be a physically based, semi-empirical model for application in connection with multi-body-systems (MBS). On the basis of tyres for a passenger car and a heavy truck the simulated steady state tyre characteristics are shown together and compared with the underlying experimental values. In the following text the possibility to link the tyre model TMeasy to any MBS-program is described, as far as it supports the 'Standard Tyre Interface' (STI). As an example, the simulated and experimental data of a heavy truck doing a standardized driving manoeuvre are compared.     

Finite element damage analysis of an underwater glider–ship collision

Underwater gliders, which are profiling autonomous underwater vehicles designed to make oceanographic measurements, are increasingly used in the coastal ocean. As they regularly surface for data transmission, gliders increasingly pose a risk for fast ships. In order to estimate the extent of damage due to collision, 3D finite element simulations of collisions between a glider and a high-speed craft with a glass-fiber reinforced plastic hull are performed. Different collision scenarios such as impact locations, angles of attack and speeds are examined. The results are compared to an analytical solution based on simplifying assumptions. Although both methods reveal consistent results, it is shown that finite element simulations are required to account for the 3D shape of the ship. The results indicate that at ship velocities exceeding 7.5 m/s (14.6 kt) the glider penetrates the ship’s hull causing severe damage to its structure.     

The impact of fuel availability on demand for alternative-fuel vehicles

We study the impact of fuel availability on demand for alternative-fuel vehicles, using data from a survey of potential car buyers in Germany. The survey was conducted as a computer-assisted personal interview and included a choice experiment involving cars with various fuel types. Applying a standard logit model, we show that alternative fuel availability influences choices positively, but its marginal utility diminishes with supply. Furthermore, we derive consumers’ marginal willingness-to-pay for an expanded service station network. The results suggest that a failure to expand the availability of alternative fuel stations represents a significant barrier to the widespread adoption of alternative-fuel vehicles.     

德国城市轨道交通的各种制式系统

鉴于中国的城市轨道交通建设已进入了加速发展的大好时期,但由于地铁项目投资巨大,工期长,而且运营、维护成本也很高,地铁不可能满足中国所有城市轨道交通发展的需求,故而必然会转向采用投资较少的其他轨道交通制式.为此,介绍了欧洲大都市轨道交通系统的主要特征,重点阐述了德国城市轨道交通的各种制式系统,包括区域线、市域线、地铁、轻轨等现代城市轨道交通的各方面情况,以供中国同行参考.     

有源电压箝位串联HV IGBT的适用性和优化(一)

介绍了5.2 kV高压绝缘栅双极型晶体管(HV IGBTs)的成功串联应用.穿通型HV IGBT串联应用时要完全控制感应过电压,最大的障碍是拖尾电流的关断问题.可以证明,采用先进的电压箝位技术能够限制因关断拖尾电流而引起的第二个电压尖峰.阳极采用载流子寿命局部分布的IGBT很适合这种应用;拖尾电流间隔时间越短,关断损耗越小.文中集中讨论了穿通型HV IGBT器件串联时的最佳通态等离子体分布,HV IGBT的最新发展趋势似乎与讨论结论相一致.未来先进的HV IGBT技术可完全减轻第一代HV IGBT串联时的困难.     

带式电动助力转向：让转向更精确 操控感更真实

对零部件供应商来说，电动助力转向（EPS）的技术挑战在于，如何达到并超越液压系统的操控感。最新的EPS技术--带式驱动EPS，尤其适用于前桥重量较大的车型，能够满足所有汽车细分市场对转向系统的高要求。     

Fuzzy Logic Traction Controllers and their Effect on Longitudinal Vehicle Platoon Systems

This paper presents two fuzzy logic traction controllers and investigates their effect on longitudinal platoon systems. A fuzzy logic approach is appealing for traction control because of the nonlinearity and time-varying uncertainty involved in traction control systems

The fuzzy logic traction controllers we present regulate brake torque to control wheel slip, which is the normalized difference between wheel and vehicle speed. One fuzzy controller estimates the peak slip corresponding to the maximum tire-road adhesion coefficient and regulates wheel slip at the peak slip. The controller is attractive because of its ability to maximize acceleration and deceleration regardless of road condition. However, we find through simulations the controller's performance degrades in the presence of time-varying uncertainties. The other fuzzy logic controller regulates wheel slip at any desired value. Through simulations we find the controller robust against changing road conditions and uncertainties. The target slip is predetermined and not necessarily the peak slip for all road conditions. If the target slip is set low, stable acceleration and deceleration is guaranteed, regardless of road condition

We also study the effect of traction control on longitudinal vehicle platoon systems using simulations. The simulations include acceleration and deceleration maneuvers on an icy road. The results indicate traction control may substantially improve longitudinal platoon performance, especially when icy road conditions exist.     

A finite element model for the Venice Lagoon. Development, set up, calibration and validation

The development, calibration and validation of a two-dimensional finite element model for the Venice Lagoon is described. The model uses a staggered grid for the spatial integration of the water levels and velocities. A semi-implicit numerical time stepping scheme is implemented, which guarantees unconditional stability for the gravity wave propagation. Because of the shallow depths in the lagoon, the model deals also with areas where flooding and drying occur.A first calibration of the model has been performed against harmonic constants of 12 tide gauges located in the lagoon. After this calibration, model output shows a good agreement with a set of water level data referring to a period of calm winds and to another data set of water level data measured in 38 stations during a period of strong winds.Meteorological data and river discharges are used to set up a 1-year long simulation that models the salinity and temperature fields. The temperature time evolution is well simulated. Comparison of model output to salinity data is not straightforward, since input data for the main rivers that discharge freshwater into the lagoon is not available for the year of reference. However, yearly averages of observed values of salinity are in a reasonable agreement with results of a climatological simulation.The presented model shows good propagation of the tidal wave and stability characteristics. It is the first step for a comprehensive model of the Venice Lagoon that deals not only with hydrodynamic variables, but also with sediment transport and ecological processes.