中欧规范T梁上部结构对比研究

各国规范均为一套系统且复杂的体系,难以用简化的分析方法进行全面的对比.对比规范的安全度,需要从作用效应和抗力效应两个方面综合考虑.作用效应需要进行不同状态的荷载组合以得到结构的组合内力,抗力效应需要考虑承载能力状态、正常使用极限状态(抗裂要求、混凝土压应力要求、刚度要求等).而桥梁结构的形式多样,汽车荷载的布置也存在很...     

一种天然气发动机尾气净化技术路线探索

为使天然气发动机满足现阶段排放要求,主流企业均采用当量燃烧+EGR+TWC技术路线,文章通过研究一种提高天然气发动机进气量的燃烧及相应的尾气净化技术,同样可以满足排放要求,且发动机无需EGR,结构简单,气耗更低,同时有效降低整车热负荷,为重型天然气发动机满足更高排放要求提供新的解决思路.     

基于MATLAB/Simulink的车辆转向稳定性的仿真研究

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....     

焊装车间机器人的节拍分析及优化设计

为了实现焊装车间降本增效的目标,对焊装车间自动生产线上机器人的生产节拍进行优化.通过分析机器人的工作时序逻辑,查找机器人不合理的工作时序,进而分析机器人的底层程序,修改程序上的问题,优化工作时序,消除机器人工作时序逻辑不合理产生的等待浪费,提升生产线的生产节拍,从而提高车间的生产效率,最终实现降本增效的目标.     

基于UG的客车主减速器锥齿轮设计平台的开发

利用UG软件二次开发了客车主减速器锥齿轮专用设计平台,论述了平台的结构设计与功能模块设计,最后给出了设计实例。     

State estimation in roll dynamics for commercial vehicles

Accurate lateral load transfer estimation plays an important role in improving the performance of the active rollover prevention system equipped in commercial vehicles. This estimation depends on the accurate prediction of roll angles for both the sprung and the unsprung subsystems. This paper proposes a novel computational method for roll-angle estimation in commercial vehicles employing sensors which are already used in a vehicle dynamic control system without additional expensive measurement units. The estimation strategy integrates two blocks. The first block contains a sliding-mode observer which is responsible for calculating the lateral tyre forces, while in the second block, the Kalman filter estimates the roll angles of the sprung mass and those of axles in the truck. The validation is conducted through MATLAB/TruckSim co-simulation. Based on the comparison between the estimated results and the simulation results from TruckSim, it can be concluded that the proposed estimation method has a promising tracking performance with low computational cost and high convergence speed. This approach enables a low-cost solution for the rollover prevention in commercial vehicles.     

Travel time estimation oriented freeway sensor placement problem considering sensor failure

Optimal sensor placement on freeway corridor is of great interest to transportation authorities. However, current traffic sensors are easily subject to various failures. Therefore, it is necessary to incorporate sensor failure into the optimal sensor placement model. In this article, a two-stage stochastic model is proposed for the purpose of travel time estimation on freeway corridor. To balance the effectiveness and reliability, a stochastic conditional value at risk (CVaR) model is also proposed. Since both models are too complicated, a customized genetic algorithm is developed. Numerical experiments show that considering sensor failure makes a significant performance improvement in the sensor placement pattern. Sensitivity analysis is also applied to investigate the impact of a number of allowable sensors and different traffic sensor failure probability.     

基于Isight和AMESim的液压减振器关键参数集成优化

在AMESim中搭建了某乘用车前悬架双筒充气式液压减振器的仿真模型。以 Isight 为平台集成AMESim,对减振器模型参数进行DOE分析,提取对减振器性能影响较大的参数,作为优化的设计变量。利用Isight中的Pointer智能求解器进行优化。结果表明,经过集成优化后的减振器阻尼力曲线与目标曲线吻合较好,符合工程实际的需要。与传统方法相比,该方法缩短了时间,提高了设计效率,可用于指导减振器阀系参数的设计与性能预测。     

基于GT-Suite的重型载货车冷却系统仿真及匹配设计

基于GT-Suite软件建立了某重型载货车发动机冷却系统的一维-准三维混合仿真模型,通过对发动机极限工况下出水温度、出水流量等计算结果与试验值对比分析,验证了仿真模型的准确性。最后在此模型基础上对发动机冷却系统进行风扇选型匹配,实现了满足整车冷却性能要求的前提下,减小了其消耗功率,从而提高了整车经济性。     

防抱死制动系统对SUV车辆操控稳定性仿真分析

针对SUV车辆在制动情况下出现的操纵性和稳定性变差现象,在CarSim软件中建立了SUV车辆动力学模型,在对开的路面对行驶的紧急制动工况进行了仿真,初步发现防抱死系统对该工况下车辆操纵稳定性的影响最大,为进一步验证,与Simulink结合建立了整车联合仿真模型,将Carsim中SUV制动过程中的制动压力导出至Simulink模型作制动仿真测试,进一步描绘出车轮侧偏角、横移角速度和偏移位移等影响操纵稳定性的参数数值变化曲线,通过分析对比,确定了紧急制动条件下为SUV车辆加装防抱死系统能达到提高操纵稳定性的目标,最终达到安全驾驶的目的。