The Available Methods to Calculate the Wheel/Rail Forces in Non Hertzian Contact Patches and Rail Damaging

In the present paper, the methods used in railway dynamics to take into account the non Hertzian multi contact patches occurring on a wheel, are summarised. Some application cases are presented as well as an explanation of the so called “squat” rail deterioration.     

Comparison of the optimum designs of center pillar assembly of an auto-body between conventional steel and ahss with a simplified side impact analysis

This study compares the optimum designs of center pillar assembly with advanced high-strength steel (AHSS) to that of conventional steel for crashworthiness and weight reduction in side impacts. A simplified side impact analysis method was used to simulate the crash behavior of the center pillar assembly with efficient computing time. Thickness optimization aims to perform an S-shaped deformation of the center pillar toward the cabin to reduce the injury level of a driver in a crash test. Center pillar members were regarded as an assembly of parts that are fabricated with tailor-welded blanks, and the thickness of each part was selected as a design variable. The thickness variables of parts that have significant effects on the deformation mechanism were extracted as the main design variables for thickness optimization based on the results of a sensitivity analysis with design of experiments. The optimization condition was constructed to induce an S-shaped deformation mode and reduce the weight of the center pillar assembly. An optimum design was obtained after several iterations with response surface methodology (RSM). Optimization was first performed with conventional steel and then with AHSS with the same procedure to optimize the crashworthiness of the center pillar assembly. After thickness optimization, optimum designs were applied to the full vehicle analysis to evaluate the validity of the optimization scheme with the simplified side impact analysis method. Then, the crashworthiness of optimum designs with conventional steel and AHSS were compared using the full vehicle analysis. This comparison demonstrates that AHSS can be more effectively utilized than conventional steel to obtain a lightweight design of an auto-body with enhanced crashworthiness.     

Factors affecting the environmental impact of pavement wear

Wear at the interface between flexible pavements and tires influences pavement life, pavement cycle costs, and tire consumption, and is a source of environmental harm. Wear-related processes evolve over time and are affected by a number of boundary conditions, such as interface fluids, water and fuels. We develop a model explaining and predicting mass losses in flexible pavements under carefully controlled conditions, and with estimation of the related environmental costs. We also employed an accelerated loading test. Under normal conditions, the environmental impact of pavement wear is not greatly influenced by mix type or volumetrics. Indeed, the presence of hazmat materials, traditional, dense mixes have an environmental impact that is appreciably lower than that of porous European mixes.     

Influence of compliance for an elastokinematic model of a proposed rear suspension

The research is carried out to improve passenger’s comfort to increase the vehicles stability in dynamic conditions. The literature available in the automotive engineering considers different topics for studying suspensions. An example represents mechanisms structure and analysis (synthesis, kinematics, and dynamics) under various operating conditions. These aspects have been approached before analytically, numerical. The current paper studies the influence of the lateral force on the contact patch of the wheel and the corresponding variations of vehicle stability parameters, such as camber angle and wheel rear track. The study is performed for a newer innovative rear suspensions mechanism which does not have a wheel track and camber angle variation, relative to the chassis, when the suspension components was considered rigid. A numerical solution is obtained through a virtual model on several commercial codes: MSC Adams, Patran, Nastran. Concerning the analysed parametes, their variation increases as the applied force is increased. Moreover, the largest variation corresponds to the case were elastic bushings and deformable links are considered.     

Connected cruise control: modelling,delay effects,and nonlinear behaviour

Connected vehicle systems (CVS) are considered in this paper where vehicles exchange information using wireless vehicle-to-vehicle (V2V) communication. The concept of connected cruise control (CCC) is established that allows control design at the level of individual vehicles while exploiting V2V connectivity. Due to its high level of modularity the proposed design can be applied to large heterogeneous traffic systems. The dynamics of a simple CVS is analysed in detail while taking into account nonlinearities in the vehicle dynamics as well as in the controller. Time delays that arise due to intermittencies and packet drops in the communication channels are also incorporated. The results are summarised using stability charts which allow one to select control gains to maintain stability and ensure disturbance attenuation when the delay is below a critical value.     

电流变流体的润滑性能研究

提出了电流变流体作为润滑剂使用的新设想,研究了电流变流体粘度的可控特性,通过试验获得了电流变流体摩擦力随电场强度、悬浮颗粒浓度、油膜厚度等因素的变化规律,为深入研究电流变流体的润滑特性奠定了基础。     

耐碰撞车辆的撞击性能

对耐碰撞车辆列车的撞击性能作了分析研究,并编制了解析大型塑性变形的动力学模拟程序。对进一步改进耐碰撞车辆的设计进行了讨论。     

Crash protection of Hybrid Electrical Vehicles for amending the KMVSS No. 91

This paper explores issues related to the electrical safety of Hybrid Electrical Vehicles (HEVs) during and after various crash events. Japanese and American federal regulations regarding occupant protection against high voltages in Electric Vehicles (EVs) and HEVs were surveyed and analyzed in this study. Front, side and rear impact tests for two types of HEVs were conducted to investigate electrolyte spillage, the retention of the propulsion battery system and the electrical isolation of the occupant. The test results met the related criteria. The test procedures and the criteria for occupant protection established through this study were amended to Korean Motor Vehicle Safety Standard (KMVSS) No. 91 to add the crash protection of the EVs and the HEVs.     

Parameter matchin and optimization for a hydraulic power-assistant system

A hydraulic power-assist system is a hydraulic regeneration system that can significantly improve fuel economy when installed on a conventional bus operating in urban traffic. This paper presents a methodology for matching a new hydraulic power-assist system (HPA) to a conventional bus. The HPA and the conventional bus were modeled using the AMESim environment. The HPA was optimized using a simulation-based orthogonal design method with two indexes, the fuel economy and the acceleration performance. According to the simulation results, the volume of the accumulator was the primary factor affecting fuel economy, and the gear ratio of the transfer case was the primary factor influencing the acceleration performance. As a result, tradeoffs between the two indexes are required for a practical operational scenario. Experimental results demonstrated that the optimal HPA installed on a conventional bus was able to satisfy the acceleration performance requirement of the vehicle and also reduced fuel consumption by 25 percent.