Bumper optimum design using the dynamically equivalent beam under various impact conditions

Nowadays it is required for the bumper system to meet the various impact conditions simultaneously; barrier impact, IIHS (Insurance Institute for Highway Safety) bumper impact and pedestrian impact. Firstly, dynamically equivalent bumper beam models were developed for each impact condition and its accuracy was verified by nonlinear finite element analysis result. Dynamically equivalent pedestrian impact beam model was developed by using the equivalent forces of bumper beam and stiffeners. Pedestrian bending angle was obtained by using this equivalent pedestrian beam model. By combining these equivalent beam models, bumper optimum design program was developed. In this optimum design program, direct search method was used for the optimization algorithm. To verify the accuracy of this optimum design program, a nonlinear finite element result was used. By using this optimum design program, it can be secured the bumper impact performances in an early design stage and it will be also contributed to reduce the design time and test costs.     

Automotive window seal design considering external aerodynamic load and surrogate constraint modeling

Installed between metallic DIW (Door in White) panel and nonmetallic door glass, automotive window seals has great influence on customers’ perception of NVH (Noise-Vibration-Harshness) performance. Recently, aerodynamic effect on ride comfort attracts increasing research interest. The external load causes unsteady pressure on glass, which is finally transferred to window seals and leads to complicated vibration and increases interior noise level. However, non-linearities of hyper-elastic material, rubber-glass contact and large deformation behavior make the construction of window seals constraint model much more difficult, thus impeding further analysis and optimization. A new window seal design method is proposed featuring in considering aerodynamics-induced load and nonlinear constraint. Firstly, by SST ? k ? ε (Shear Stress Transport) turbulence model, external flow field of full-scale automotive is established by solving three-dimensional, steady and uncompressible Navier-Stokes equation. With re-exploited mapping algorithm, the overall aerodynamic pressure is extracted and matched to local window as external loads for seals, thus taking into account high speed fluid-structure interaction. Secondly, based on functional equivalence and mathematical fitting, new surrogate constraint model is presented. The unitedseal CLD (Compression Load Deflection) curve is synthesized after translations and transformations from two semi-seal CLD experimental measurements of inner and outer lips. It is then fit to complex exponential function, making seal constraint equivalent to a surrogate elastic constraint with variable stiffness. Experiment is performed to verify the constraint surrogation effectiveness. Finally, case study of window seal design under high speed is investigated. After seal optimization based on the new method, windows seals’ maximal displacements have decreased. The improved seal-glass fitting status shows better NVH quality of window seal in high-speed condition.     

某汽车排气管吊耳支架拓扑优化设计

用变密度法建立结构拓扑优化的数学模型,利用有限元分析软件Hyperworks中的Optistruct模块对某车型汽车排气管吊耳支架进行拓扑优化设计,并对优化后的结构进行强度分析和台架试验。试验结果表明,优化后的结构强度要优于优化前的结构强度。应用此方法可大大缩短汽车钣金类零件的设计周期,减少生产成本。     

基于新型液冷板的电池热管理系统多目标优化

为提升电池热管理系统(BTMS)散热效果,采用计算流体力学(CFD)和基于快速非支配排序遗传算法(NGSA-II)的多目标优化相结合的方法设计优化了一种新型液冷板模型。通过电池实验,得到不同放电倍率下单体电池产热量。以通道夹角、通道宽度、冷却液的质量流量为设计变量,平均温度、温度标准差和压降为目标函数,采用拉丁超立方体抽样(LHS)方法,在设计空间中选取了35个设计点,利用响应面近似模型(RSM)拟合出目标函数的表达式。结果表明:在5C放电倍率下,优化后液冷板的散热性能得到有效提升,与初始模型相比,液冷板的平均温度和温度标准差分别下降了11%、51.2%,压降仅增加了3.3Pa。     

汽车减振器阀系参数建模及CAD软件开发

利用节流压力与流量以及阀片变形之间的关系,建立了减振器阀系参数设计数学模型和优化目标函数.在此基础上,开发了一套减振器阀系参数CAD软件,并对其特点进行分析.通过实例,利用该软件对阀系参数进行CAD设计,并对减振器进行了阻力特性试验,其结果与特性要求值相近.这表明所建立的减振器阀系参数设计模型是正确的,所开发的阀系参数CAD软件是可靠的,对于减振器设计具有实际推广价值.     

基于拓扑优化的车架结构可靠性设计

为了提高某载货车车架的力学性能并减轻重量,将可靠性理论引入车架结构的优化设计。考虑了多种行驶工况的冲击载荷对车架的破坏作用,给出多工况条件下拓扑优化结果,建立满足各总成的布置和实际行驶要求的新设计结构,基于结构可靠性和有限元法对新设计车架的结构参数进行了可靠性优化设计。理论分析和车架的实际应用情况表明,该车架设计合理,说明该优化设计方法进行车架结构设计的有效性和可行性,为结构优化设计提供一种思路。     

特种车辆重载电动轮用轮毂电机热特性分析及冷却水道优化

为了准确分析轮毂电机温度场,基于电磁场有限元分析,采用考虑旋转磁化及谐波磁场的方法计算铁耗,并计算了轮毂电机各部件生热率。采用基于有限体积法的流固耦合分析和基于热网络法的磁热耦合分析,分别计算了额定工况下轮毂电机温度场,将轮毂电机温升试验和仿真结果进行了对比。结果表明,基于有限体积法的流固耦合分析得出的绕组稳态温度计算误差为1.8%,基于热网路法的磁热耦合分析计算误差为2.5%,验证了两种温度场分析方法的正确性。对不同结构冷却水道的热阻和压降进行了理论分析,基于Pareto遗传算法对螺旋型水道进行多目标优化,在保证额定工况电机稳态温升基本不变的情况下使水道压降降低了22.9%。     

基于拓扑优化的某重型车桥桥壳轻量化设计

对某重型车桥桥壳在设计工况下的静强度性能进行了有限元分析,并对该桥壳结构进行了轻量化设计。采用拓扑优化方法,以初始设计作为优化的基结构,以重量最轻为目标函数,以结构的静强度性能为约束条件,进行了优化迭代计算。轻量化设计后,减轻了桥壳的重量,且轻量化结构满足强度要求。     

基于改进图分解法的多材料车身结构优化设计方法

针对概念设计阶段的车身结构轻量化设计,提出了一种可实现车身多材料结构设计的分层迭代优化方法。该优化方法的设计变量中,除常见的板厚、材料外,还包括装配设计中的拓扑连接,以实现“将合适的材料用在合适的部位”的要求。分层迭代优化的第1层以拓扑连接为设计变量,采用图分解和NSGA-II对车身装配拓扑结构进行多目标优化,最大化车身弯扭刚度和1阶固有频率;第2层对板厚和材料进行多目标优化,最小化车身质量和材料成本。最终采用基于模糊集合的评分公式选定综合最优解,实现了考虑成本的车身结构轻量化设计。     

基于拓扑优化的某重卡轮毂轻量化设计

对某重卡前轴轮毂在设计工况下的静强度性能进行了有限元分析,并对该轮毂结构进行了轻量化设计.采用拓扑优化方法,以最大设计空间为优化的基结构,以重量最轻为目标函数,以结构的静强度性能为约束条件,进行了优化迭代计算.轻量化设计后,减轻了轮毂的重量,且轻量化结构满足强度要求.     

某重卡下支架有限元分析及轻量化设计

对某重卡下支架在设计工况下的静强度性能进行了有限元分析,并对该下支架结构进行了轻量化设计。采用拓扑优化方法,以最大设计空间为优化的基结构,以重量最轻为目标函数,以结构的静强度性能为约束条件,进行了优化迭代计算。轻量化设计后,减轻了下支架的重量,且轻量化结构满足强度要求。     

Structural design of an outer tie rod for a passenger car

This study proposes a structural design method for an outer tie rod installed in a passenger car. The weight of the outer tie rod is optimized by using the aluminum alloy Al6082M, which is developed as a steel-substitute material, and applying structural optimization techniques. The high strength aluminum with improved mechanical properties was developed to reduce the weight of the outer tie rod. The newly developed aluminum alloy Al6082M is applied as the material of the outer tie rod. The static strength due to inertia force, durability and buckling performances are considered in the structural design of the outer tie rod. At the proto design stage of a new outer tie rod, it is cost-effective to utilize FE (finite element) analysis to predict each of these performances. In addition, the current trend in the structural design of automobile parts is to use optimization techniques to reduce the weights of the parts. First, for an arbitrary base design, the static strength, the life cycle and the buckling load are calculated to check whether the design satisfies its criteria. Then, the critical performance is selected so as to include its loading condition only in the optimization process. In this study, the metamodel based optimization process using kriging is adopted to obtain the minimum weight satisfying the critical design requirement. Then, the feasibility of the determined optimum shape is investigated against the other performances. Finally, the optimum design of outer tie rod is modified by considering forging efficiency. The performances of the final design are investigated through simulation and experiment.     

汽车外流空气动力模拟

本文求解雷诺平均三维不可压Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程，模拟轿车外流场，发展了方便快捷的前后处理技术。计算了东风ＡＦ微型计算结果与风洞试验结果很好地相符，开发的ＣＦＤ软件可成为理解和优化轿车外流的有效工具。     

动力电池包热管理设计与优化分析

针对动力电池包热管理中系统温度不均匀的问题,本文以某款液体循环冷暖一体化热控方式的电池包为研究对象,通过Ansys-fluent对其液冷回路进压降仿真,并优化液冷回路,最后通过实验验证优化前后系统的散热/加热性能,得出流量均匀性越好在液冷和液热时,电池包内电芯间的温差越小,散热以及加热效率更高。为后续热管理设计可将流道的设计作为重点考察对象进行优化。     

渗流作用下被动桩桩后土体的破坏机理

基于离散元的颗粒流方法和计算流体动力学的Navier-Stokes方程,建立了渗流作用下的被动桩桩后土体变形分析模型;分别用墙和圆形颗粒模拟桩和土体固相颗粒,用Navier-Stokes方程描述土体渗流,研究了渗流作用下桩后土体的变形破坏过程、影响因素和防治措施。结果表明:桩后土体在渗流作用下形成土拱效应,但随着土拱附近颗粒楔紧,局部水力梯度增大,土拱从拱脚开始破坏;渗透压力对桩后土体能够提供的最大阻滑力影响较大;增大桩表面粗糙度或者在桩后侧端部增加过滤墙结构能够提高被动桩对桩后土体提供的最大阻滑力。研究结果揭示了渗流作用下桩后土体的变形破坏规律,可为渗流条件下被动桩工程的优化设计提供依据。     

气道稳流试验的变压差试验分析

用变压差试验方法测量了6108发动机缸盖进气道的流动特性。试验全过程不需要随时调节模拟气缸内的压差为恒定值。确定气门最大升程时模拟气缸内的初始压差后，就可采集试验中的流量和涡流转速等参数。随着气门升程变小，模拟缸内的压差自由增大。试验结果与恒压差试验相同，同样可以得到Ricardo和FEV计算方法的平均流量系数和涡流比。测量精度符合要求，操作程序简单可靠，易于实现气道稳流试验的全自动化。     

FE modeling method for a headform used in pedestrian protection simulations

Finite element models of headforms are used in experimental simulations of pedestrian protection. In this study, a quick and accurate method for FE modeling of the headforms was developed. This method entailed the initial definition of the dimensional parameters for the mass, centroid, and inertial moment properties of the headform. The equations governing these properties were constructed using the dimensional parameters as design variables. The dimensional parameters meeting the requirements of the relevant regulations were obtained by solving these three equations. A design optimization model was constructed for the material parameters of the outer part of the headform. In this model, the parameters of the material used in the FE model were considered as design variables; the difference between the peak acceleration in a side-impact simulation test and the average value of the regulated acceleration range was used as the objective function; the first-order natural frequency, which was required to be greater than 5,000 Hz, was defined as one of the constraints; the peak drop acceleration, which was required to be within the regulated range of values, was defined as the second constraint. The material parameters were obtained by solving the optimization model. These material parameters meet the dynamic requirements of the regulations for headforms. Based on these three parameters, an FE model of a headform can be constructed quickly and accurately.     

变压差气道稳流试验台的应用

气道性能(涡流强度、流量系数)对发动机的动力性、经济性和排放有重要影响。气道稳流试验台是目前最常用的综合评价进气道流动特性的实验装置,根据测量方法的区别可分为变压差和定压差。其中变压差试验方法相对于传统的定压差试验,具有快捷、高效的特点,减少气道稳流试验中的调整气道压差为恒值的操作程序。本文基于TUST-101气道稳流试验台的实际应用,对比了2种试验方法的差异,并根据实际应用对试验台进行部分改进以提高精度。     

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.     

4G15D缸内直喷发动机油气分离模拟分析及试验验证

某4G15D缸内直喷发动机由于在缸盖罩位置布置高压油泵,导致气缸盖罩油气分离部分空间被占用,需要重新设计该款缸内直喷发动机油气分离结构型式。使用CFD仿真分析软件对发动机油气分离器内气液两相流场进行了数值模拟,分析了3种不同结构(改进前后)迷宫式油气分离器的流动分布、压力损失,采用离散模型模拟油滴粒子喷射,假定油滴粒子与壁面碰撞后即被捕捉,进而得出不同直径油滴的油气分离效率,根据仿真分析结果选择最优化设计方案;设计了一种简单而有效的试验方法对油气分离器分离效率间接进行验证。结果表明,采用CFD软件模拟计算方法能够计算出油气分离器油气分离效率,获得的结果反映了流动本质。在模拟分析过程中,油滴直径设定在1～15μm范围内时,根据所需要的油气分离效率优化设计油气分离结构,满足了最终产品要求。同时,在计算分析准确的前提下,提出了相应试验验证方法。