Shape optimization of a torsion beam axle for improving vehicle handling performance

In this study, shape optimization was conducted for a vehicle’s rear suspension torsion beam to improve its dynamic handling performance. To determine the design variables affecting the vehicle roll characteristics, a sensitivity analysis was conducted using the result of a Taguchi experiment with 6 factors in 8 runs. The upper and lower-flange lengths and web thickness of the torsion beam section, as well as the vertical height difference between the inner and outer of torsion beams, were determined as design variables through sensitivity analysis of the opposite wheel travel test for optimization of the torsion beam axle. The Box–Behnken experimental design with 4 factors and 27 runs was performed using the selected design variables and by performing opposite wheel travel analysis according to the experimental design, and the response surface functions of the roll stiffness, roll steer coefficient, roll center height, and mass of the torsion beam were generated. Using these response functions, shape optimization was conducted for the torsion beam of the rear suspension system. Dynamic performance analysis was performed by applying the optimized H-shaped torsion beam to the rear suspension of the vehicle dynamics model, and it was validated that the dynamic response performance of the optimized vehicle was improved.     

比亚迪汉空气动力学开发

汉是比亚迪基于全新纯电动车平台开发的一款车型,为增加续驶里程对整车的风阻系数提出了极高的要求。全新的造型设计风格对风阻开发带来很大挑战,为实现风阻目标搭建了一套适用的空气动力学开发流程,并以 CFD仿真为主要开发工具,分别完成外造型、前舱、车底部、主动进气格栅和低风阻轮辋等附件的空气动力学开发,最后通过实车风洞试验进行验收。对该车型的风洞试验仿真对标发现,采用分离涡模拟（Detached Eddy Simulation,DES）湍流模型可以获得较高的风阻仿真精度。     

考虑气动阻力和横风稳定的汽车车身多目标优化设计

综合考虑了气动阻力特性和横风稳定性,对车身外形参数进行了多目标自动优化设计。综合利用参数化建模技术、计算流体力学(CFD)仿真、试验设计方法、响应面模型和智能优化算法,集成Pro/Engineer参数化建模和ICEM网格划分工具以及Fluent仿真软件,在多学科优化平台modeFRONTIER上,搭建了一种自动优化设计流程。利用该流程,基于遗传算法(GA)对MIRA快背式模型车身几何外形进行了改型设计,得到了考虑车身气动阻力特性和横风稳定性的最优权衡设计解集。该结果使得气动阻力因数降低了5.2%,侧向力因数降低了5.8%。因而,实现了车身气动阻力和横风稳定性的多目标优化。     

轿车发动机冷却风扇CFD仿真分析及降噪研究

介绍汽车冷却风扇气动性能的CFD仿真方法,对风扇性能随风扇叶片参数的变化规律进行深入探讨.在此基础上,利用仿真方法对长安V805基准车发动机散热器风扇和冷凝器风扇进行优化设计.试验验证结果表明,优化设计在保证冷却性能的前提下,达到了降低风扇气动噪声的效果.     

FSC赛车空气套件CFD优化设计

在满足FSC赛车设计规则要求前提下,对空气套件进行了结构优化设计,重点完成了赛车尾翼的优化设计和分析。利用CFD技术对赛车车身模型进行了外流场分析,并通过在赛车尾部加装不同间隙和攻角的尾翼,进行车身外流场模拟对比分析,研究尾翼在改善赛车气动特性方面的影响规律,研究确定了空气动力学装置在不同比赛项目时的调教策略。通过对比分析赛车车辆周围气流的压力分布和速度分布规律,研究高速赛车的负升力效果,对于提高赛车的操纵稳定性和安全性具有非常重要的意义,对于指导赛车尾翼的正确安装、确定尾翼在不同比赛项目时的调教策略有一定的指导意义。     

典型汽车尾流结构的研究

本文通过对车身周转流态的烟流流态的显示试验，尾流的速度和总压测定试验。研究了典型车型的尾流结构及其对空气动力特性的影响。     

Application of Aerodynamic Actuators to Improve Vehicle Handling

This exploratory study considers applications of active aerodynamic devices for suppressing parasitic motion and for improving the response of vehicles to steering, within the scope of the linear dynamic behaviour. A three DOF linear model is chosen to describe the side slip, yaw and roll motion of a baseline front-wheel steered vehicle. The improvements in performance of the base-line vehicle that are achievable by the application of direct yaw and roll moments are determined when either an open loop control pre-filter or a state feedback control law based on LQR design is applied. Unlike the former control, the state feedback control is unable to make the body side-slip angle vanish. The feedback control performance of each of the two moment actuators has been examined separately and then jointly. The advantages of combining the open loop and feedback dual actuator configurations are demonstrated using the two-degree of freedom control scheme. It is found that the scheme yields a spectacular performance but demands unreasonably large moments from the actuators in the context of available aerodynamic forces. On the other hand, the demand on direct yaw and roll moment of actuators is modest when the actuators are controlled using the LQR feedback only and if the control design is used to track a desired yaw rate trajectory and simultaneously to reduce the parasitic rolling motion. Significant improvements in handling and dynamic stability of a base-line vehicle can be achieved by aerodynamically generated direct yaw and roll actuator moments provided the target control performance is reasonable. The configurations of aerodynamic actuators considered are feasible for improving vehicle handling in cornering on motorways but more work remains to be done to explore alternative aerodynamic configurations that give rise to less side effects and higher lift coefficients.     

Application of Aerodynamic Actuators to Improve Vehicle Handling

This exploratory study considers applications of active aerodynamic devices for suppressing parasitic motion and for improving the response of vehicles to steering, within the scope of the linear dynamic behaviour. A three DOF linear model is chosen to describe the side slip, yaw and roll motion of a baseline front-wheel steered vehicle. The improvements in performance of the base-line vehicle that are achievable by the application of direct yaw and roll moments are determined when either an open loop control pre-filter or a state feedback control law based on LQR design is applied. Unlike the former control, the state feedback control is unable to make the body side-slip angle vanish. The feedback control performance of each of the two moment actuators has been examined separately and then jointly. The advantages of combining the open loop and feedback dual actuator configurations are demonstrated using the two-degree of freedom control scheme. It is found that the scheme yields a spectacular performance but demands unreasonably large moments from the actuators in the context of available aerodynamic forces. On the other hand, the demand on direct yaw and roll moment of actuators is modest when the actuators are controlled using the LQR feedback only and if the control design is used to track a desired yaw rate trajectory and simultaneously to reduce the parasitic rolling motion. Significant improvements in handling and dynamic stability of a base-line vehicle can be achieved by aerodynamically generated direct yaw and roll actuator moments provided the target control performance is reasonable. The configurations of aerodynamic actuators considered are feasible for improving vehicle handling in cornering on motorways but more work remains to be done to explore alternative aerodynamic configurations that give rise to less side effects and higher lift coefficients.     

Aerodynamic Design of a Solar Road Vehicle

Solar road vehicles have very specific design requirements. This makes their aerodynamic characteristics quite different from classic sedan vehicles. In the present study, the computational model of a typical solar road vehicle was developed to investigate its aerodynamic forces and flow characteristics. Computations were performed assuming the steady viscous flow and using the Reynolds-averaged Navier Stokes equations along with the k-ω turbulence model. The obtained results indicate some important findings that are commonly not present for classic sedan vehicles. In particular, a contribution of the viscous drag force to the overall drag force is considerably larger (41 %) than it is the case for the standard passenger road vehicles, where the form drag force dominates over the viscous drag force. Surface pressure distribution patterns indicate a favorable aerodynamic design of this vehicle. In particular, larger pressure coefficients on the top of the vehicle body as compared to the bottom surface contribute to increasing a downforce and thus the vehicle traction. The airfoil-shaped crosssection of the designed cockpit canopy has favorable properties with respect to reduction of the aerodynamic drag force.     

多连杆后悬副车架结构及衬套优化设计

结合某车型开发工作,针对该车型所采用的新型四连杆后悬架系统,采用先进的多学科优化技术对后桥结构及衬套刚度进行全面优化设计,并对遗传算法、模拟退火及混合多梯度探测等多目标优化算法在该系统中的应用进行了详细的对比论证。     

Design Optimization of a Rear Independent Suspension for the Korean Light Tactical Vehicle

Steering and suspension handle the direction of a vehicle according to the driver’s intentions and control the disturbance from the road surface while supporting the vehicle body. The static and dynamic characteristics of two systems are critical factors for the ride comfort and the directional stability. In the layout stage, the hard points of steering and suspension systems are determined. In the next design stage, the detailed design of the system, including gearboxes, springs, shock absorbers, and control links, is carried out. While the optimal hard points of a suspension are determined at the precedent design, interference with other peripheral components should be carefully examined in the detailed design process. In the case of the design point change should be made to avoid the interference, subsequent position and shape changes of the link mechanism are required. Therefore, there is a need to examine the optimization of suspension compliance characteristics with chassis design changes and the durability performance of the modified design. This study proposes an integrated analysis method for the design optimization and the durability evaluation of such optimized design specifications of the rear independent suspension for a military vehicle.     

某纯电动汽车后副车架安装点刚度分析与优化设计

在某款纯电动汽车的设计开发过程中,为满足NVH及整车安全要求,提高乘车舒适性及满意度,利用CAE软件建立含后副车架安装点的白车身有限元模型,并进行刚度分析,根据CAE分析结果提出优化方案,再对优化方案进行刚度分析,最终找出有效提高后副车架安装点刚度的最佳方案,满足性能要求,节约产品开发成本、缩短产品开发周期,同时为后副车架结构改进和优化设计提供重要依据。     

不同几何参数车轮的汽车流场数值模拟研究

在以前研究的基础上对单个车轮进行了深入的仿真模拟,增加了对车轮辐板外形的模拟。通过对同一型号的、有不同辐板开孔的车轮进行分组研究发现,车轮几何参数的改变不仅影响车轮局部流动,还影响整个汽车的流场特性。进一步分析流场计算结果表明,车轮周围流场中涡量变化是引起汽车以及车轮气动阻力系数改变的主要原因。     

Actively translating a rear diffuser device for the aerodynamic drag reduction of a passenger car

This research aims to develop an actively translating rear diffuser device to reduce the aerodynamic drag experienced by passenger cars. One of the features of the device is that it is ordinarily hidden under the rear bumper but slips out backward only under high-speed driving conditions. In this study, a movable arc-shaped semi-diffuser device, round in form, is designed to maintain the streamlined automobile??s rear underbody configuration. The device is installed in the rear bumper section of a passenger car. Seven types of rear diffuser devices whose positions and protrusive lengths and widths are different (with the basic shape being identical) were installed, and Computational Fluid Dynamics (CFD) analyses were performed under moving ground and rotating wheel conditions. The main purpose of this study is to explain the aerodynamic drag reduction mechanism of a passenger car cruising at high speed via an actively translating rear diffuser device. The base pressure of the passenger car is increased by deploying the rear diffuser device, which then prevents the low-pressure air coming through the underbody from directly soaring up to the rear surface of the trunk. At the same time, the device generates a diffusing process that lowers the velocity but raises the pressure of the underbody flow, bringing about aerodynamic drag reduction. Finally, the automobile??s aerodynamic drag is reduced by an average of more than 4%, which helps to improve the constant speed fuel efficiency by approximately 2% at a range of driving speeds exceeding 70 km/h.     

基于多目标粒子群优化算法的某轻型商用车操纵稳定性优化研究

针对某轻型商用车稳态回转时侧倾度偏大的问题对其悬架进行优化改进。基于ADAMS/car搭建整车多体动力学模型,通过前悬架反向平行轮跳试验、后悬架理论计算验证了悬架仿真模型的准确性。进行整车稳态回转工况和转向盘中间位置转向工况仿真分析,结果表明,车身侧倾度偏高。为实现操纵稳定性优化分析的流程自动化,提出了基于modeFRONTIER的联合仿真方法。以悬架设计参数为优化变量,以汽车的侧倾度与横摆角速度响应滞后时间为优化目标,采用拉丁超立方试验设计方法拟合得到混合代理模型,并结合多目标粒子群优化算法对悬架系统进行多目标优化,获得了悬架系统优化方案。优化结果显示,在不影响平顺性的前提下,汽车车身侧倾度降低了13.93%,横摆角速度响应滞后时间降低了2.75%,整车操纵稳定性得到了提升。     

某轻型客车横向稳定杆的匹配研究

针对某轻型客车操稳性能较差的问题,结合该车前后悬架型式和生产实际,重新匹配优化了其前后横向稳定杆。根据优化结果试制了样件,装车后进行了操稳性能试验。优化后该车操稳性能得到提升了,证明了优化方案有效、可行。     

后地板安全带固定点结构优化设计

针对后地板安全带固定点的3种结构形式,对后地板安全带固定点相关法规进行了介绍,并对后排安全带固定点的强度进行了分析。通过分析某车型后地板安全带固定点强度失效原因,对其后地板安全带固定点结构和焊点进行了优化,优化后的结构在模具冲压和车身焊接中均未出现问题,满足了静拉试验相关法规要求。     

bZ3纯电动轿车的空气动力性能开发

作为比亚迪丰田电动车科技有限公司第1款纯电动轿车,bZ3的能耗要求极高,也给空气动力学性能开发带来了很大的挑战。为实现这一目标,通过采用计算流体力学（Computational Fluid Dynamics,CFD）仿真和风洞试验相结合的方法,对车身造型、车底、前舱进气管理、车轮、密封等部位进行了持续的优化验证。最终bZ3在风洞中进行实车试验验收,空气阻力系数达到0.218,在同级别车型中处于领先水平。通过两种不同仿真方法对比研究发现格子玻尔兹曼（Lattice Boltzmann Method,LBM）方法整体精度较高,但对于底部气流的模拟精度还有待提升。     

某重型越野汽车驾驶室后悬置有限元分析及改进

本文以ANSYS软件为工具,对某型号越野汽车驾驶室后悬置支架进行受力分析,详细准确地确定了汽车驾驶室后悬置支架的受力情况和应力分布部位,依托分析结果对支架结构进行优化,达到降低驾驶室后悬置支架关键部位应力的目的,并通过实际试验进行验证,结果显示优化后的支架有效地改善了关键部位的应力,解决了支架断裂问题,提高了整个驾驶室悬置系统的可靠性能。     

增程式电动SUV行驶稳定性优化设计

结合某增程式电动SUV开发所面临的问题,通过理论分析、悬架K&C分析、整车操稳性分析、悬架系统K特性多目标优化等手段,在保证底盘零部件通用化的基础上,对后悬架K特性进行优化设计,提出优化方案。通过制作设计样车,并对设计样车进行主观评价,底盘性能问题得到很好地解决,为后续底盘性能提升奠定了良好基础。