基于MotionView整车虚拟试验场仿真的后转向节强度分析

由于车辆行驶状况复杂多样,传统静态工况无法复现各类恶劣路况下后底盘转向节真实应力,因此在利用MotionView建立整车刚柔耦合多体动力学模型的基础上,将后转向节利用柔性体进行模拟;在进行虚拟试验场仿真分析的同时采用模态综合法计算结构动应力,得到后转向节最高应力位置及发生时刻.仿真结果与整车道路试验结果的对比表明仿真方法准确.     

基于Abaqus的稳定杆失效分析及优化

为提高稳定杆扭转性能,保证整车稳定性、乘坐舒适性和行驶安全性,基于Abaqus/Standard,以Abaqus的接触及非线性分析为基础,研究仿真与试验的相关性,达到稳定杆台架试验失效模式在仿真模型中的复现.结合复现结果提出优化方案,解决稳定杆断裂失效问题.     

The effect of solvent and ionomer on agglomeration in fuel cell catalyst inks: Simulation by the Discrete Element Method

We simulate agglomeration in different fuel cell catalyst ink solutions using Discrete Element Method. Carbon support is modelled as particles in various inks with ionomer and various solvents. The particles interact with particle-pair forces resulting in agglomerate build-up. The classical colloidal theory with van der Waals and electric double layer forces underestimates the ink stability, which motivates the development of a new model of polymer force between particles. The force is activated when there is a bridging of polymer between the carbon black particles, and the strength is dependent on the ionomer interaction with the solvent by the dielectric constant. A critical dielectric constant was defined for which ionomer form a web-like polymer network that increases the ink stability. This modification can explain the trend of the ink stability, and the model can simulate the effect of different solvents on the agglomerate size distribution with good agreement with experimental results.     

皮卡车钢板弹簧断裂分析

通过断口分析、化学成分分析、金相检验和硬度测试对皮卡车的钢板弹簧断裂的原因进行了分析。结果表明:钢板弹簧表面存在凹坑造成了应力集中,而且板材的非金属夹杂物超标,降低了疲劳强度,在交变应力载荷的作用下,最终造成钢板弹簧发生了早期疲劳断裂。     

某四缸发动机平衡轴抱轴问题的分析与解决

平衡轴系统配合间隙的设计要考虑形状公差及位置公差、材料线膨胀系数等因素的综合影响,考虑不全面会导致实际工作的配合间隙不合理,过大或者过小都可能导致抱轴问题的发生。优化配合间隙能够有效地解决抱轴问题,但需要重新评价对整机润滑系统、NVH性能的影响并加以验证。试验结果表明:间隙的优化有效解决了平衡轴抱轴问题,同时对系统油压、NVH性能带来影响在可接受的范围内。     

增压直喷汽油发动机早燃现象改善的研究

低速大负荷早燃现象是制约增压直喷汽油发动机低速性能提升的主要因素之一,早燃易导致发动机火花塞烧蚀、活塞熔顶等质量问题,所以在发动机设计开发过程中必须对早燃问题加以优化改善。阐述了早燃产生的机理,更换不同机油、改变压缩比以及空燃比进行试验,结果表明：更换机油以及改变空燃比能够降低早燃频次,改变压缩比对早燃无影响。     

Influence of the dispersion state of ionomer on the dispersion of catalyst ink and the construction of catalyst layer

The ionomer state in the catalyst ink of a proton exchange membrane fuel cell (PEMFC) plays a critical role in the formation of the catalyst/ionomer interface on the catalyst layer (CL). In this study, the effect of ionomer dispersion state on catalyst ink dispersion and the construction of a reasonable CL was investigated. The study of catalyst inks revealed that the dispersion of n-propanol (NPA) -ionomer dispersion or sonication could effectively reduce the catalyst particle size in inks. For shear-dispersion and homogenizer-dispersion inks, the catalyst particle size was reduced from 6.17 nm to 5.12 nm and from 5.12 nm to 4.67 nm, respectively. The ionomer dispersion was capable of significantly reducing the size of agglomerates in the ink, which resulted in a reduction in the particle size of agglomerates on the surface of the cathode CL and an improvement in its flatness. The pore size distributions of the MEA cathode catalyst layers showed that water bath ultrasonic treatment of the ionomer could result in a more reasonable pore structure for the catalyst layer. The single-cell test revealed that changing the ionomer's dispersion state could significantly increase the fuel cell's output voltage to 0.707 V at 1000 mA cm⁻², and the cell's power density to 1028 mW cm⁻² at 2000 mA cm⁻².     

高压共轨柴油机后喷对机油稀释影响的试验研究

针对高压共轨柴油机为实现DPF的主动再生,实施燃油后喷导致发动机机油稀释的问题进行试验研究。试验使用两次后喷,第一次后喷在上止点后20°~40°,第二次后喷在上止点后120°~180°。研究表明:通过适量使用后喷1,尽量减小后喷2的油量,适当调整后喷2的喷油正时,可实现达到DPF主动再生目标温度的同时,最大程度地降低由于后喷作用引起的机油稀释现象。     

正面碰撞试验用50%假人胸部刚度研究

通过对50%假人胸部标定试验的研究,指出假人胸部可看作弹性结构,在指定的条件下,具有特定的刚度。通过对胸部在不同安全带作用下的刚度表现进一步研究,指出普通安全带作用下胸部刚度为300N/mm,预紧限力式安全带作用下胸部刚度为200N/mm。     

轿车驾驶室声学响应仿真分析

(针对某轿车后排乘客耳旁噪声水平过高的问题,建立结构声学耦合有限元模型。通过声灵敏度分析得到左前悬架安装点位置为主要传递路径,利用板件贡献量分析,找到贡献量较大的板件。最终通过改进板件阻尼材料达到了降低噪声的目的,并得到试验验证。通过此方法,可以方便的得到贡献量较大的传递路径和贡献量较大的板件,为降低驾驶室噪声水平提供一种有效的评价和改进的手段。