Robust design optimization of suspension system considering steering pull reduction

This paper presents robust design optimization method to reduce steering pull phenomenon. One of the biggest causes of steering pull phenomenon is tolerance of suspension system such as hard point, spring, damper and bush. Therefore, the relationship between suspension systems and steering pull phenomenon has as nonlinear characteristics. But, it can be very difficult to evaluate the analytical design sensitivity. Thus, it is impossible to directly apply a well-developed optimization algorithm based on gradient information. To avoid these difficulty, this study uses sequential approximation optimization process based on a meta-model. The robust design process has 28 random design variables with tolerance. For efficient design process, the sample variances for the design goals are approximated from meta-models. The proposed approach required only 62 evaluations until it converged. Optimal design reduced the drift by 80% and its deviation by 38.7%, respectively. This result proves that the suggested design method of suspension system is effective and useful.     

Robust design optimization of suspension system by using target cascading method

This study presents the robust design optimization process of suspension system for improving vehicle dynamic performance (ride comfort, handling stability). The proposed design method is so called target cascading method where the design target of the system is cascaded from a vehicle level to a suspension system level. To formalize the proposed method in the view of design process, the design problem structure of suspension system is defined as a (hierarchical) multilevel design optimization, and the design problem for each level is solved using the robust design optimization technique based on a meta-model. Then, In order to verify the proposed design concept, it designed suspension system. For the vehicle level, 44 random variables with 3% of coefficient of variance (COV) were selected and the proposed design process solved the problem by using only 88 exact analyses that included 49 analyses for the initial meta-model and 39 analyses for SAO. For the suspension level, 54 random variables with 10% of COV were selected and the optimal designs solved the problem by using only 168 exact analyses for the front suspension system. Furthermore, 73 random variables with 10% of COV were selected and optimal designs solved the problem by using only 252 exact analyses for the rear suspension system. In order to compare the vehicle dynamic performance between the optimal design model and the initial design model, the ride comfort and the handling stability was analyzed and found to be improved by 16% and by 37%, respectively. This result proves that the suggested design method of suspension system is effective and systematic.     

Design optimization of an injection mold for minimizing temperature deviation

The quality of an injection molded part is largely affected by the mold cooling. Consequently, this makes it necessary to optimize the mold cooling circuit when designing the part but prior to designing the mold. Various approaches of optimizing the mold cooling circuit have been proposed previously. In this work, optimization of the mold cooling circuit was automated by a commercial process integration and design optimization tool called Process Integration, Automation and Optimization (PIAnO), which is often used for large automotive parts such as bumpers and instrument panels. The cooling channels and baffle tubes were located on the offset profile equidistant from the part surface. The locations of the cooling channels and the baffle tubes were automatically generated and input into the mold cooling computer-aided engineering program, Autodesk Moldflow Insight 2010. The objective function was the deviation of the mold surface temperature from a given design temperature. Design variables in the optimization were the depths, distances and diameters of the cooling channels and the baffle tubes. For a more practical analysis, the pressure drop and temperature drop were considered the limited values. Optimization was performed using the progressive quadratic response surface method. The optimization resulted in a more uniform temperature distribution when compared to the initial design, and utilizing the proposed optimization method, a satisfactory solution could be made at a lower cost.     

桥梁结构耐久性设计方法研究

分析了目前桥梁结构耐久性研究中存在的问题。在比较了各国几种主要耐久性设计理论和方法的基础上,提出了一种新的耐久性设计思路和方法,即利用耐久度来衡量结构保持耐久性的能力,通过计算耐久性指标来评判某一时刻结构耐久性能否满足设计要求。该方法强调了多种因素共同作用、结构体系和构件荷载类别以及桥梁寿命周期经济性对耐久性设计的影响,具有概念明确、形式简单、便于应用等特点。     

Innovative design optimization strategy for the automotive industry

In order to effectively solve modern automotive design problems including the results of nonlinear FEA and multi-body dynamics, a progressive meta-model based design optimization is presented. To reduce the number of initial sample points, two sampling methods are introduced. Then, for efficient and stable construction of meta-models, three metamodel methods are newly introduced which are numerically based on the singular value decomposition technique. To design a practical system considering manufacturing tolerances and optimizing multiple performances, a robust design optimization, 6-sigma constraints and multi-objective strategies are implemented when solving the approximate optimization problem constructed from the meta-models. Until the convergence criteria are satisfied, the initially developed meta-models are progressively improved by adding only one point that minimizes the approximate Lagrangian in the consecutive optimization iterations. Finally, one validation sample and four automotive applications are solved to show the effectiveness of the proposed approach.     

闵浦大桥双层钢结构抗火设计

S32申嘉湖高速公路上海闵浦大桥是一座跨越黄浦江的双层公路特大桥,主桥为主跨708m的双层双索面双塔斜拉桥。大桥主跨采用板桁结合钢桁梁,为大型双层钢结构,如果下层发生车辆火灾,将对大桥钢结构安全形成威胁,提出了双层大桥特殊的抗火安全性问题。因此,闵浦大桥双层钢结构在火灾下的安全性评估与抗火设计就显得极其重要,介绍了闵浦大桥抗火研究与设计,相关结论可供国内类似大型钢结构借鉴。     

Energy management and design optimization for a series-parallel PHEV city bus

Series-parallel PHEV city buses combine the advantages of series and parallel configurations and have been used in China. However, the design and energy management of series-parallel PHEV city buses based on Chinese driving conditions still need to be investigated. In this paper, an equivalent consumption minimization strategy is provided to optimize energy management for series-parallel PHEV city buses, and the process of the equivalent consumption minimization strategy for series-parallel is presented in this paper. Compared with the validated rule-based energy control strategy, ECMS shows a fuel economy improvement of 8.2 % in the CBCD (Chinese Bus Driving Cycle). Based on the optimal energy management, a design for a generator motor in the series-parallel configuration has been processed. The fuel consumption has been shown to decrease, with an increase in generator power, because the system with the higher generator power can work at a higher efficiency in the series mode and operate the engine in the high efficiency area in the parallel mode. Besides, in terms of costof- ownership for a PHEV bus for lifetime of 8 years, although the high generator power will lead to high purchase cost for series-parallel PHEV bus, a series-parallel PHEV city bus with a generator of 100 kW maximum power will still show small advantage in cost-of-ownership, based on current motor price and natural gas price.     

Aerodynamic design optimization of rear body shapes of a sedan for drag reduction

This study proposes an aerodynamically optimized outer shape of a sedan by using an Artificial Neural Network (ANN), which focused on modifying the rear body shapes of the sedan. To determine the optimization variables, the unsteady flow field around the sedan driving at very fast speeds was analyzed by CFD simulation, and fluctuations of the drag coefficient (C _D ) and pressure around the car were calculated. After consideration of the baseline result of CFD, 6 local parts from the end of the sedan were chosen as the design variables for optimization. Moreover, an ANN approximation model was established with 64 experimental points generated by the D-optimal methodology. As a result, an aerodynamically optimized shape for the rear end of the sedan in which the aerodynamic performance is improved by about 5.64% when compared to the baseline vehicle is proposed. Finally, it is expected that within the accepted range of shape modifications for a rear body, the aerodynamic performance of a sedan can be enhanced so that the fuel efficiency of the sedan can be improved. The YF SONATA, a sedan manufactured by Hyundai Motors Corporate, played a major role in this research as the baseline vehicle.     

碳纤维复合材料发动机罩行人保护性能的试验验证

为研究碳纤维复合材料发动机罩行人保护性能,与同结构金属发动机罩进行了对比试验验证。试验结果表明,碳纤维复合材料发动机罩的头部合成加速度峰值比金属发动机罩平均低30%,在结构加强位置类似的情况下,其更有利于降低头部伤害值;碳纤维复合材料发动机罩对发动机舱内布置影响较小;碳纤维复合材料发动机罩在受到行人头部冲击后能够保证结构的完整性,有利于降低事故维修成本。     

公路工程中多种资源均衡优化的遗传算法设计

利用遗传算法对公路工程进度优化中的资源均衡优化问题进行了探讨,给出了利用遗传算法对整个问题的求解设计思路,对公路工程多种资源均衡优化中利用遗传算法优化时染色体设计、优秀个体的充分利用以及遗传操作后不合理结果的处理提出了解决方法,为今后遗传算法在公路工程进度优化中的应用提供了有益的思路。最后设计了求解流程图。     

基于C-NCAP五星碰撞的主体铝制纯电动车正碰车身框架结构设计

论文针对纯电动车与传统燃油车在造型和布置上的差异化特点带来的车身正碰框架中的设计难点和痛点,提出了一套完整、可行且有效的主体铝制量产正碰车身框架结构设计方法,此方法专门针对纯电动布置进行实体建模和正碰工况下的拓补优化设计,制定正碰主体铝材料结构设计方案,以实现吸能效率的提升,保障乘员舱的安全可靠性,同时兼顾轻量化和共线...     

基于能量解耦的汽车动力总成悬置系统优化设计

为了解决某款车的动力总成悬置系统振动问题,结合多自由度系统振动解耦和固有频率匹配理论,应用ADAMS建立动力总成悬置系统模型进行仿真分析。同时以解耦率目标函数,通过MATLAB软件中的遗传算法对悬置系统进行了优化。结果表明,对悬置刚度进行优化能有效提高解耦率,改善系统的NVH性能。     

面向行人综合保护的汽车前部结构参数优化

针对行人头部和下肢的综合保护,建立了行人汽车碰撞的多刚体模型.选取保险杠、发动机罩和风窗玻璃等的诸多几何参数作为设计变量,以行人头部和下肢损伤指标最小为优化目标,采用基于Pareto最优的多目标遗传算法对汽车的前部结构参数进行了优化.结果表明,发动机罩与水平面的夹角对头部损伤影响最大,保险杠离地高度对下肢损伤影响明显,优化得到的3组结构参数对行人综合保护有较好的效果.     

Shape design optimization of interior permanent magnet motor for vibration mitigation using level set method

This paper presents a new optimization method to obtain the structural design of permanent magnet motor which can reduce the mechanical vibration. The optimization problem is formulated to minimize a multi-objective function including the mean compliance of the whole stator for maximizing the stiffness under the magnetic force and the torque ripple by aligning torque profiles to a constant target value for maximizing the magnetic performance, with constraint for material usage. The level set function is introduced for representing the structural boundaries and calculating the material properties. A coupled magneto-mechanical analysis is performed to verify the vibration characteristic of the motor system and obtain the design sensitivities. To confirm the usefulness of the proposed design method and to obtain the optimum structural design for low vibration motor, a design example of 20 kW interior permanent magnet motor developed for the power train of a hybrid electric vehicle is provided.     

过街行人对人行立交设施满意度模糊综合测评

过街行人对人行立交设施的满意度，往往左右着过街行人的过街方式，也间接地反映了该人行过街立交设施的综合服务性能。在调查分析的基础上，借鉴用户满意度模糊综合测评的方法，建立了过街行人对人行立交设施满意度模糊综合测评模型。     

天然气/汽油两用燃料汽车点火提前角适应性优化设计

为了使天然气/汽油两用燃料汽车燃用不同的燃料时,能自动改变点火提前角,从而保证发动机在不同的转速时都在最佳点火提前角下工作,研究了两用燃料汽车点火提前角的优化调整方法,通过试验得到了发动机燃用天然气和汽油时,最佳点火提前角相差的相关角度,研制了一种利用89C2051单片机定时器/计数器T0、外部中断INT0以及相关硬件电路组成的自适应燃料点火器。这种点火器能根据燃料转化开关的位置,通过单片机控制实现对两用燃料汽车不同点火提前角的精确控制。试验结果表明:安装这种自适应燃料点火器的发动机功率、扭矩增大,能耗下降,这种自适应燃料点火器能够一定程度地提高两用燃料汽车发动机的动力性和燃油经济性。     

城市早高峰步行可达范围研究

根据步行与其他交通方式对比的优势距离及对城市早高峰居民步行出行实际调查数据,研究城市步行出行的可达范围。     

Multidisciplinary design optimization for front structure of an electric car body-in-white based on improved Collaborative Optimization method

In this investigation, an Improved Collaborative Optimization (ICO) method based Multidisciplinary Design Optimization (MDO) framework for front structure of an electric car body-in-white (BIW) is presented. ICO method based on 1-norm and dynamic flabby coefficient, which shows relatively high efficiency and accuracy, is first proposed here and prepared to conduct MDO in this work. Finite element analysis (FEA) results of the baseline design for an integral battery electric car body structure show that its front part needs to be optimized designed in the consideration of full-lap frontal crashworthiness. Selecting the thicknesses of 5 components, with global mass and free basic frequency constraints, a multidisciplinary size optimization problem is implemented using both ICO and standard CO methods combined with OLHS technique, metamodel and SQL algorithm. Optimal scheme based on ICO method is preferred and selected for its better performance compared with result calculated by standard CO method. The energy absorption of redesigned front body structure is finally raised by 14.2 % with 55 iterations.     

A design methodology for mechatronic vehicles: application of multidisciplinary optimization, multibody dynamics and genetic algorithms

A design methodology for mechatronic vehicles is presented. With multidisciplinary optimization (MDO) methods, strongly coupled mechanical, control and other subsystems are integrated as a synergistic vehicle system. With genetic algorithms (GAs) at the system level, the mechanical, control and other relevant parameters can be optimized simultaneously. To demonstrate the feasibility and efficacy of the proposed design methodology for mechatronic vehicles, it is used to resolve the conflicting requirements for ride comfort, suspension working spaces and unsprung mass dynamic loads in the optimization of half-vehicle models with active suspensions. Both deterministic and random road excitations, both rigid and flexible vehicle bodies and both perfect measurement of full state variables and estimated limited state variables are considered. Numerical results show that the optimized vehicle systems based on the methodology have better overall performance than those using the linear quadratic Gaussian (LQG) controller. It is shown that the methodology is suitable for complex design optimization problems where: (1) there is interaction between different disciplines or subsystems; (2) there are multiple design criteria; (3) there are multiple local optima; (4) there is no need for sensitivity analysis for the optimizer at the system level; and (5) there are multiple design variables.     

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。