基于ABAQUS的双箱自卸半挂车车架有限元分析

利用有限元软件ABAQUS6.9对新开发的某双箱自卸式半挂车车架进行建模、网格划分及应力分析,得到了该车架在多种工况下的应力分布和位移变形图,通过对计算结果进行分析,校核该车架强度满足设计使用要求,并为其结构改进与优化设计提供有效参考。     

汽车雨刮电机减速器异响机理研究

汽车雨刮电机减速器异响将引起车内噪声,对其进行机理研究可以为此类问题的故障诊断提供依据,对于提高车辆NVH性能具有重要意义。首先对发生减速器异响的汽车雨刮电机进行噪声测量,通过分析信号的时频特征提出电磁异响和摩擦异响两种异响类型,然后分别对两类异响进行机理分析,发现异响产生的原因和传递路径,最后运用试验修正的方法建立了转子的精确有限元模型并进行模态分析,验证了两类异响的产生机理,明确解释了两类异响的成因,为提取雨刮电机减速器异响的故障特征参数提供依据。     

Eco-friendly fermentation module for maximization of hydrogen harvesting from fatty restaurant waste diluted with grey water

Valorization of fatty restaurant waste (RW) is an economically and environmentally promising approach due to the enriched high biodegradable organic content of this substrate. However, the lipid fraction has an adverse impact on the hydrogen fermentation process. Thus, three staged hybrid reactors (HR1, HR2 and HR3) connected in series were investigated for lipid degradation and H₂ harvesting from the codigestion of fatty RW and grey water. A hydrogen harvesting volume of 0.3 ± 0.02 L/L.d., was recorded in HR1, and lower values of 0.22 ± 0.1 and 0.11 ± 0.06 LH₂/L.d were obtained in HR2 and HR3, respectively. The phyla Actinobacteria (6.4%), Bacteroidetes (10.9%), Chloroflexi (45.1), and Proteobacteria (22.4%), which degrade carbohydrates, lipids and proteins, were dominant in HR1 and highly reduced in HR2 and HR3. Nevertheless, the abundance of the phylum Firmicutes was 16.6% in HR1 and increased to 21.7% in HR3. Staging of the anaerobic digesters highly distributed the hydrolytic and acetogenic syntrophic microbes, creating a unique fermentation medium for H₂ harvesting from RW diluted with grey water.     

起动电机模态特性试验分析

针对汽车厂提出的起动电机在发动机整机振动激励下不能出现共振的要求,分别利用振动台正弦激振和力锤冲击激振,对该型起动电机进行了振动模态特性试验分析,求得起动电机在安装状态下最低固有频率为528.31Hz,满足固有频率高于整机振动激励频率2.5倍的要求。起动电机在实车状态下的振动测试表明,在该发动机转速范围内,发动机的整机振动不会激起起动电机的共振。配置了上述发动机和起动电机的轿车,已大批量上市约两年,起动电机至今也未发生因异常振动导致的故障。     

Uniformity analysis at MEA and stack Levels for a Nexa PEM fuel cell system

The Nexa™ power module is evaluated at membrane-electrode-assembly (MEA) and stack levels. The I–V Curves of the Nexa™ PEM fuel cell system is measured using periodic current interruption to maintain isothermal stack temperature. The uniformity analysis is mainly performed on the load of 800 W for all MEAs in 10 individual Nexa™ stacks. Statistical data show that the MEA voltage without an external load averages 224 mV higher than that with a load of 800 W. The MEA voltage difference is especially pronounced around the two cells at the air compressor side. The average difference is 8.8% and the highest difference is 13.1% between the minimum MEA voltage in the stack and the mean value. This voltage difference reveals a possibility to increase the product power capability and cut the cost per kilowatts by improving the weak performance electrodes or MEAs in the stack.     

平板式钻井液叠层筛网自由振动分析

平板式钻井液叠层筛网在钻井液振动筛上得到广泛应用,研究振动筛的结构参数和安装参数对其自由振动的影响可为振动筛和筛网的设计及使用提供依据。提出将使用螺栓绷紧方法安装的筛网模型简化为弹性支承多跨单向连续矩形薄板模型,忽略筛网上的结构非线性特征,整张筛网看作由被底部橡胶支承条划分为k+1块的小矩形板组成。基于弹性矩形薄板振动理论,建立每小块矩形薄板的自由振动方程,提出各跨间薄板的连续性条件,利用传递矩阵方法推导出了整张筛网的传递方程,根据边界条件得到筛网自由振动的频率方程。对某一型号平板式叠层筛网的自由振动特征方程进行数值求解,得到不同螺栓预紧力、不同橡胶支撑条数目及刚度下筛网的固有频率,数据分析表明这三种参数均与筛网的固有频率呈正相关性,并且互相之间有一定影响。     

锂盐对LAGP-PEO复合固体电解质及全固态LFP锂离子电池性能的影响

将Li1.5Al0.5Ge1.5(PO4)3（LAGP）与少量PEO(LiX)复合,采用溶液浇注法制备了以LAGP为主相的固体复合电解质,研究了LiClO4、LiTFSI、LiBOB 3种锂盐对固体复合电解质离子电导率、电化学稳定窗口、与锂负极界面的化学稳定性和电化学稳定性的影响以及锂盐种类对LFP固态电池循环及倍率性能的影响。研究结果表明,采用LiClO4、LiTFSI、LiBOB 3种锂盐制备的固体复合电解质分解电压均超过5 V,具有较好的电化学稳定性。LAGP-PEO(LiTSFI)固体复合电解质的离子电导率以及室温对锂界面的稳定性相对更高。LAGP-PEO (LiBOB)与锂的界面在60 ℃时相对更稳定。与之对应,采用LAGP-PEO(LiTSFI)和LAGP-PEO(LiBOB)固体复合电解质的LFP全固态电池,分别在25 ℃和60 ℃具有最高的比容量和最好的循环稳定性。     

Experimental investigation on the mechanism of variable fan speed control in Open cathode PEM fuel cell

This study aims to reveal the mechanism of variable fan speed control in Open cathode PEM fuel cell (OC-PEMFC) by the experiments, which analyze the effects of variable fan speed on the operating parameters under different fuel cell loads. The operating parameters are cell temperature, stack voltage, voltage uniformity, and parasitic power. The results reveal that the fan speed has strong effects on the operating parameters: (1) it affects the temperature distribution and overheats the middle cells of fuel cell stack, especially, when it operates at high power; (2) it affects the variation trend of the voltage under different loads; (3) it affects the voltage uniformity, which can be improved via forced convection; (4) it affects the system efficiency due to the parasitic load consumed by the fan. Considering the varying effects of these operating parameters on performance, durability and system efficiency under different fuel cell loads, the variable fan speed control should adapt the variation of fuel cell loads and weigh multiple operating parameters.     

Fast identification of power change rate of PEM fuel cell based on data dimensionality reduction approach

The efficiency, reliability and lifespan of the fuel cell are strongly affected by the dynamic load variation of its output, which renders it desperate to investigate the influence of the power change rate on the fuel cell. In this study, three data dimensionality reduction algorithms are applied to identify the power change rate of the fuel cell in a less time-consuming way. To achieve that, the cell voltages of the stack as high-dimensional dataset is instantly projected onto the one-dimensional eigenvector space by principal component analysis (PCA), Fisher discriminant analysis (FDA) and locally linear embedding (LLE), respectively. The eigenvalue of one-dimensional eigenvector has the potential for instantly identifying the power change rate of the fuel cell and can be used as a feedback parameter in the control, which can improve the dynamic response, reliability, and lifespan of the fuel cell stack. According to the performance indicators of the algorithms including monotonicity, linearity and program execution time, the result shows that the PCA algorithm is the best-matched method for the real-time control of the fuel cell system. In the end, this study discussed some potential applications of this method in the fuel cell system, be it to be used alone or in a vehicular fuel cell hybrid system.     

强流脉冲电子束处理50BA钢耐腐蚀性能

目的研究强流脉冲电子束(HCPEB)对50BA钢表层组织和表面耐腐蚀性能的影响。方法对50BA钢进行不同脉冲次数的表面处理,用扫描电镜观察组织变化,并在NaCl和去离子水配成的3.5%NaCl腐蚀溶液中(室温)进行动电位极化曲线测试。结果经HCPEB处理后,50BA钢试样表层晶粒细化且产生了细小均匀分布的针状马氏体,随着脉冲次数的增加,表面趋于光滑。试样表面的自腐蚀电位从-0.660 V提高到-0.629 V,腐蚀电流从1.48×10~(-6) A降低到8.36×10~(-7) A。随着脉冲次数的增加,试样表面的腐蚀电流降低,腐蚀电位升高,腐蚀速率降低,腐蚀倾向性减小,其中50次脉冲处理后试样表面的耐蚀性能最好。结论经HCPEB处理后,表层组织发生相转变,表面趋于光滑和获得的均匀细小针状马氏体从理论上解释了50BA钢耐腐蚀性能的提高。为了提高50BA钢的耐腐蚀性,应将脉冲次数控制在30次以上,且越高越好。