道路不平致车身俯仰运动对气动升力影响研究

为了探究路面不平产生的车身俯仰运动对气动升力的影响,结合汽车动力学参数与路面参数,得到不同路面空间频率下的车身俯仰运动规律,并利用重叠网格技术实现了车身绕质心的正弦俯仰运动,通过对比风洞试验数据验证了湍流模型的准确性。通过车身表面压力、车身周围流场结构分析了车身俯仰时的气动升力变化规律。结果表明,同一俯仰角下,车尾下摆时产生的气动升力数值大于车尾上摆;车尾下摆时,由于前轮腔的“吸力”效应,车底气流速度降低;车尾上摆时,由于前轮腔的“排斥”效应,车底气流速度增大。     

车身俯仰运动对气动升力的影响

为了明确汽车车身俯仰运动对气动升力的影响,建立了某轿车车身俯仰运动模型,并采用大涡模拟对其进行了准静态及瞬态模拟分析。利用动网格技术实现了车身绕前轴中心的正弦俯仰运动,并通过稳态的1∶3模型风洞试验验证了大涡模拟法的准确性。从车身周围流场、车身表面压力等不同的角度对气动升力变化规律及机理进行了分析。结果表明:车身正弦俯仰运动时,瞬态气动升力也随之发生周期性变化,与准静态下气动升力的变化完全不一致,准静态模拟与试验条件下气动升力变化趋势基本一致;瞬态模拟时最大和最小气动升力系数都约为准静态模拟时的3倍;瞬态模拟时,由于流场中气流受到惯性以及黏性作用的影响,导致最大和最小气动升力系数都出现在车身接近水平位置时,与准静态模拟及试验中出现位置完全不同;车身俯仰运动时,车身上表面的压力变化相对较小,而车底板的压力变化很大,且对气动升力有着重要影响,车身从不同方向运动到水平位置时,底板后端的气动压力相差近40N;后轮胎周围的流场变化对气动升力也有重要影响,车身从不同方向运动到水平位置时,后轮罩中心截面上相同位置处和后轮胎后端表面的压力系数最大差值均约为0.4。     

空气囊车身悬置系统在汽车中的应用

文章研究了空气囊车身悬置系统主要部件的结构、功能及原理,并简单介绍了其国内外发展概况。从专业的角度分析了其目前国内外市场上的应用现状。根据其结构形式分析提出了其发展的关键技术,并大胆预测了未来的技术发展趋势。通过分析与预测说明空气囊车身悬置系统在未来中国市场上将起着重要的作用。空气囊车身悬置系统必将是未来中国车身悬置系统市场上的“主力军”。     

中巴车车身悬置系统的开发与应用

结合ＳＹ６６９０车身悬置系统的开发，介绍了车身悬置系统的隔振降噪原理及ＳＹ６６９０车身悬置系统的设计方法。通过测试分析，得出了ＳＹ６６９０车身悬系统的隔振降噪效果，指明了车身悬置系统在中巴车减振降噪方面的应用价值。     

发动机悬置装置的新发展

发动机悬置又称作发动机支承,它的主要作用是将发动机柔性地支承在车身(或底盘)上,以减少发动机传给车身的振动和噪声。近年来,随着主动控制式发动机悬置的采用,可以说发动机悬置装置有了新的发展。 一、弹性元件式发动机悬置(图1)     

车身多点橡胶悬置系统布置形式研究

分析了平置式和V型布置式车身多点橡胶悬置系统的运动规律及特点,并以某6×6型军用车辆为模型样车,基于ADAMS对其进行了振动特性的仿真研究与优化对比。结果表明:橡胶悬置元件在V型布置中具有更好的应用价值;V型布置式车身多点橡胶悬置系统拥有更好的隔振效果,尤其在垂向和侧倾方向。     

某牵引车车身有限元模型验证

建立了某牵引车车身的有限元模型,运用Hyperworks软件对该牵引车车身骨架进行了强刚度分析,在分析基础上进行了重点部位的电测布片,测试了该牵引车车身的满载静态应力应变、满载动态应力变化,通过测试结果分析,验证了该牵引车车身的有限元模型较为理想,进一步为优化设计、降低制造成本提供了可靠性支持。     

基于能量解耦法的客车动力总成悬置隔振性能优化

针对某客车车身振动过大的问题,利用ADAMS对动力总成悬置系统进行解耦分析,得出车身振动过大的原因为动力总成悬置系统软垫刚度值不匹配,导致系统在六个振动模态方向上的能量分布相互耦合,使振动加剧。通过优化计算悬置软垫在不同方向上的刚度值,使系统在不同方向上的振动能量解耦,从而提高悬置系统隔振率,达到减振的目的,并经过测试验证。     

液压互联悬架模糊切换控制设计以及试验验证(英文)

设计一种基于汽车运动-模态的液压互联悬架模糊切换控制策略,利用主要汽车运动模态能量作为实时控制目标实现能量的均衡分配。首先建立汽车悬架动力学模型,然后设计运动-模态识别方法以及切换控制策略,针对汽车车身垂向、车身俯仰以及车身模态设计3个不同的模糊控制器,建立整车仿真平台以及在四通道悬架试验台上进行试验,分别验证该主动悬架系统的有效性。结果表明,此新型的主动互联悬架可以有效降低俯仰运动以及侧倾运动,从而起到防侧翻的效果,悬架操纵性能得到提高。     

剪切式车身悬置独立限位结构的优化

车身悬置系统作为非承载式车身与整体车架连接的弹性件,主要起到支撑车身及隔离振动的作用。车身悬置系统的性能对整车的舒适性、操纵稳定性、安全性能及可靠性均有重要影响,需要重点研究及设计。本文论述了优化某SUV车型剪切式车身悬置的限位结构以及隔振性能的设计过程,研究了剪切式车身悬置设计要素之间的关系,并提出一种新颖的限位结构,实现了优化设计目标,积累了宝贵的设计经验。     

Semi-Active Attitude and Vibration Control

The paper discusses the attitude and vibration control of a passenger car on the basis of a full vehicle model. The analysis presented consists of two parts: (I) The introduction of a newly developed semi-active anti-roll/pitch system, (ii) An example of an actively suspended full vehicle model using a simple control strategy to improve ride comfort. The attitude control using semi-actively generated compensation forces prevents the car from rolling in curves and pitching during braking or accelerating. The strength of the system is the small energy consumption. The performance of the combination of both attitude and vibration control can compete with a fully active suspension system.     

矩形断面综合管廊线缆舱通风阻力系数数值仿真研究

为探究城市综合管廊通风阻力影响因素和计算方法,通过调研综合管廊通风系统设计和交通隧道通风阻力的相关研究成果,得到综合管廊线缆舱单位长度通风阻力系数的计算公式。建立综合管廊线缆舱三维数值模型,利用ANSYS FLUENT软件并采用标准双方程模型对通风障碍物比例约为15%的综合管廊线缆舱室内部支架、线缆和热效应对通风的阻力影响进行模拟。分析得到： 1)相较于内部无支架、线缆的综合管廊线缆舱,有支架、线缆时对通风阻力影响极大; 2）随着通风风速的增大,综合管廊线缆舱通风阻力逐渐增大,而通风阻力系数减小,且逐渐趋于稳定; 3）进口空气温度、线缆发热及舱内温度产生的热效应对通风的阻力效应有一定的影响,且随着进风温度增大,通风阻力和通风阻力系数逐渐降低。     

轿车发动机舱左纵梁修改前后碰撞性能对比仿真研究

应用动态非线性有限元方法对某型轿车左纵梁修改前后发动机舱的变形过程进行了计算机模拟对比。运用ANSYS/LS-DYNA软件,在合理简化的基础上,建立了左纵梁修改前后发动机舱的有限元模型,模拟了整车质量改变和左纵梁结构变化对发动机舱碰撞变形和吸能的影响。计算结果表明,修改后发动机舱的碰撞变形形态未发生变化,在变形量和加速度值方面都有所增加,但未产生较大差异。     

The mechanism for the coupler and draft gear and its influence on safety during a train collision

A mechanical model of the coupler and draft gear was established to study the mechanism during an intercity train collision. The model includes four rigid bodies, one spherical joint, two nonlinear torsion spring units and two nonlinear hysteresis units. Simulation and test results show that the axial characteristics of the model are reasonable and the model can reasonably simulate the pitching movement of the coupler. The influence of the coupler and draft gear on the collision behaviour of the train is analysed considering a four-section intercity train. The results show that during the collision process, the amount of compression of the middle coupler is an important factor influencing the pitching deflection angle. The pitching motion posture of the coupler changes with the initial pitching deflection angle, but the initial pitching deflection angle has little effect on its yawing deflection angle. When the pitching angle of the middle coupler is elevated, as the elevation angle increases, the derailment risk of the ‘A’ end bogie of the previous vehicle increases, whereas the risk of derailment of the ‘B’ end bogie of the subsequent vehicle decreases. When the pitching angle of the middle coupler is depressed, the derailment trends for the front and rear bogies exhibit the opposite trend from that of the elevation angle. As the train collision speed increases, the pitching motion of the middle coupler is limited to forcing a yawing motion, causing the yawing deflection angle to increase sharply, which causes the wheel–rail lateral force to increase rapidly. From this, the derailment risk of the bogie increases, which further causes large displacement lateral buckling of the train. An anti-lateral buckling device can limit the yawing deflection angle of the middle coupler, preventing lateral buckling from large displacement and decreasing the risk of derailment.     

Semi-Active Attitude and Vibration Control

SUMMARY

The paper discusses the attitude and vibration control of a passenger car on the basis of a full vehicle model. The analysis presented consists of two parts: (I) The introduction of a newly developed semi-active anti-roll/pitch system, (ii) An example of an actively suspended full vehicle model using a simple control strategy to improve ride comfort. The attitude control using semi-actively generated compensation forces prevents the car from rolling in curves and pitching during braking or accelerating. The strength of the system is the small energy consumption. The performance of the combination of both attitude and vibration control can compete with a fully active suspension system.     

商用车驾驶室主动噪声控制技术试验研究

以某商用车驾驶室主动噪声控制系统的开发过程为主线,进行了一系列主动噪声控制技术的试验研究。通过对驾驶室内实际噪声的测试、分析,确定了以发动机2阶、4阶和6阶噪声为降噪对象的主动噪声控制方案：建立商用车驾驶室主动噪声控制模型．并采用驾驶室内真实噪声信号进行了计算机降噪效果仿真试验：最后在实际驾驶室驾驶员位置建立双通道主动噪声控制系统,并进行了实车降噪效果测试。试验结果表明：利用主动噪声控制技术改善以发动机低频、周期噪声为主要噪声源的商用车驾驶室内噪声环境是一条有效的技术途径。     

考虑人体热调节的乘员表面温度分布及车内热环境的数值仿真和试验

为研究在瞬态变化的车内热环境下的人体表面温度分布情况及舱内热环境对乘员热舒适性评价的影响,以冬季某轿车乘员舱内热环境为研究对象,实车测试暖风系统开启后车内热流场的动态变化,建立乘员舱流场和温度场的瞬态仿真模型,综合考虑环境参数和人体新陈代谢等因素以及车内热环境与人体热调节模型间的耦合关系.研究结果表明:仿真计算与试验测...     

Three-dimensional override analysis of crashed railway multiple units

Override simulations of two train units in frontal collision have been carried out using multi-body dynamics. The aim of this paper is to investigate the possible factors influencing the overriding behaviour throughout frontal collisions. In addition to the initial vertical offset defined in the standard EN 15227, the pitching motion of vehicles has a great effect on the overriding phenomenon. It depends on several factors, such as collision mass, pitching frequency, height of the centre of mass above the rail level. In this paper, it has been shown that the overriding phenomenon is more sensitive to variations in pitching frequency and height of the centre of mass, compared with the factor of the collision mass. Moreover, it has been demonstrated from simulation results that a 200-kN vertical force is required for the combined anti-climber devices (100 kN for each side anti-climber) to constrain the vertical relative motion between crashed train units.     

Development of motorcycle training simulator

From September 1996, motorcycle training schools have been required to introduce training to predict danger scenes in mixed traffic by using a motorcycle riding simulator. In order to obtain a high educational effect, it is necessary to reproduce the riding sense such as banking sense and pitching sense. Sensory evaluation was made on the said riding sense by using a simulator which has five degrees of freedom of roll, yaw, pitch, vertical direction and steer. The evaluation disclosed that the rotation center of roll and pitch largely influenced the banking sense and the pitching sense. The behavior of the newly developed simulator is controlled by three degrees of freedom of roll, pitch and steer, keeping similar riding sense to the simulator with four degrees of freedom.     

前舱引流板对温度场的改善分析

重点介绍了前舱引流板对温度场改善的分析过程。针对某项目设计过程中,前舱温度场不达标的情况,提出增加前舱引流板的建议,通过CFD(Computational Fluid Dynamics)分析对比,增加前舱引流板后,前舱的流场及各主要零部件的温度情况改善明显,使进入前舱的气流利用率最大化,解决了整车开发过程中,前舱温度场难以达标的问题。