混合动力车辆动力系统建模与仿真

以并联式混合动力车辆为研究对象,基于MATLAB／Simulink软件,建立了发动机、电动机、蓄电池以及整车仿真模型,制定了整车控制策略．仿真结果表明,应用该策略对发动机与电机间的功率输出进行协调控制,能明显提高整车燃油经济性,并能够维持SOC在规定的工作区间变化．     

Fatigue-crack growth in 2090 AlLi alloy

The fatigue-crack growth kinetics of the 12.7 mm thick 2090-T8E41 alloy plate vary significantly with plate thickness location. The apparent fatigue-crack growth rates in the midthickness location are substantially lower than those in the surface region at intermediate and high applied stress intensity ranges. The lower crack growth rates are related to the extraordinarily tortuous fatigue profile which induces high crack closure levels. Such a tortuous crack profile appears to be primarily a consequence of the alloy's intense crystallographic texture and its great propensity for planar slip.     

基于支持向量回归的轴承故障定量诊断应用

针对轴承故障状态特征与故障大小之间存在非线性关系,提出利用支持向量回归机建立轴承故障大小与状态特征之间的定量诊断模型,并给出了基于支持向量回归的定量诊断策略和诊断流程。在获取轴承不同故障大小的特征量的基础上,建立了轴承故障定量诊断的支持向量回归模型,将其用于轴承故障的定量识别。结果表明,该方法能够有效地判断出故障的大小。进一步将该方法与人工神经网络方法比较,结果说明了支持向量回归方法在轴承故障定量诊断方面具有更好的适应性。     

基于响应面模型的注塑件精密成型工艺优化

为了提高注塑件品质,对注塑件进行了成型工艺优化.结合中心复合试验设计,采用Moldflow软件和响应面模型方法,拟合得到注塑件二阶响应面模型,由响应面模型获得成型最佳产品品质的工艺参数组合.采用Moldflow软件对该工艺参数组合进行了分析.结果表明:采用响应面模型预测与Moldflow软件分析得到的体积收缩率相差约0...     

氧化石墨烯改性碳纤维复合材料抗冲击行为研究

使用单层纳米氧化石墨烯（NGO）粒子对环氧树脂进行改性处理,采用真空辅助树脂传递模塑成型工艺制备了[±45/0/90]_2S铺层角度下的纯树脂及单层NGO改性碳纤维复合材料（CFRP）层合板。通过落锤冲击试验、超声C扫描检测、冲击后压缩试验等对纯树脂及单层NGO改性CFRP进行实验研究。结果表明,纯树脂及单层NGO改性CFRP在损伤阻抗及损伤容限实验中均存在拐点现象,且拐点出现在相同深度位置,其中纯树脂CFRP拐点位置为0.51 mm,单层NGO改性CFRP拐点位置为0.43 mm;相对于纯树脂CFRP,单层NGO改性CFRP可以显著提高复合材料的抗冲击性能及冲击后的压缩性能;通过对冲击后凹坑深度及凹坑面积进行数据模拟,可以用拟合公式实现对复合材料的损伤预测。     

平面型缺陷断裂评定的BS 7910标准简介

主要介绍BS7910标准中的平面缺陷断裂评定方法，共分为三个级别。它对实际的金属结构评定是非常有意义的。     

新型多自由度足力测试装置设计

介绍了一种新的六自由度足力测量装置的结构.首先描述了测试装置的硬件结构,然后运用坐标变换等数学工具,根据点在平面上的投影确定了移动体在空间的位移,并通过刚度矩阵,给出了该装置的数学模型及六维力向量的信息获取方法.试验结果表明,该装置方案可行,结构合理,数学模型正确,刚度矩阵的标定能满足精度要求,基本上达到了使用程度.     

油气弹簧叠加阀片设计方法及对节流缝隙影响

利用开阀压力和阀片变形计算公式,建立了油气弹簧单片节流阀片厚度解析设计式。利用叠加阀片等效厚度和应力计算公式,建立了叠加阀片设计方法。对开阀条件进行研究,建立了调整垫片厚度设计公式。利用开阀压力和流量之间关系,建立油气弹簧节流缝隙设计公式。在此基础上,对阀系参数设计影响因素进行了分析。通过实例,对油气弹簧阀系参数进行了设计,对叠加阀片等效厚度、开阀特性和应力强度进行验证,并对油气弹簧进行了特性试验。特性分析和试验结果表明,油气弹簧阀系参数设计应考虑叠加阀片的影响。     

Microbubble Phenomenon in the Grease Lubricating Film Induced by Micro-Oscillation

A microbubble phenomenon induced by micro-oscillation in the grease lubricating film confined within a nanogap between a highly polished steel ball and a smooth glass disc has been observed with an interferometer. Experimental results show that when the micro-oscillation frequency is a constant value, the microbubble number increases with the micro-oscillation amplitude. When the micro-oscillation amplitude is a constant value, the microbubble number increases with the micro-oscillation frequency when the latter is lower than the critical value and decreases with the micro-oscillation frequency when it is higher than the critical value. Theoretical models and analyses have been used to discuss the bubble formation and describe the characteristics of bubble movement.     

Modeling a hydrogen pressure regulator in a fuel cell system with Joule–Thomson effect

Fuel cell vehicles offer significant sustainability benefits by eliminating tailpipe emissions, increasing powertrain efficiency, and utilizing hydrogen that can be supplied from various sources including renewables. A pressure regulator in the hydrogen storage system on a fuel cell vehicle is an important component to ensure that the hydrogen delivery to the fuel cell stack meets the pressure and temperature requirements. A validated model of the regulator can be used to support the product design and optimization of the operating strategy. In this work, a pressure regulator model has been developed to capture the hydrogen discharge behaviors from the compressed hydrogen tank to the fuel cell stack. The focus of the model is to develop the pressure and temperature relationship at the regulator outlet given the inlet conditions from the storage tank. Besides the ideal-gas based derivation for pressure response, the model has used a constant-enthalpy approach to capture the hydrogen temperature increase associated with the pressure drop due to the Joule–Thomson effect. The model was validated with various testing data including hysteresis and dynamic flow conditions, showing satisfactory agreement. The validated model was then used for parametric studies. The modeling results concluded that the regulator inlet temperature has the strongest influence on raising the outlet temperature, while the regulator inlet pressure is an important factor although secondary to the inlet temperature. The comprehensive regulator modeling developed in this work provides the foundation for assessing and optimizing a key dynamic component in the hydrogen storage system.