Computation of wheel–rail contact force for non-mapping wheel–rail profile of Translohr tram

Translohr tram has steel wheels, in V-like arrangements, as guide wheels. These operate over the guide rails in inverted-V arrangements. However, the horizontal and vertical coordinates of the guide wheels and guide rails are not always mapped one-to-one. In this study, a simplified elastic method is proposed in order to calculate the contact points between the wheels and the rails. By transforming the coordinates, the non-mapping geometric relationship between wheel and rail is converted into a mapping relationship. Considering the Translohr tram’s multi-point contact between the guide wheel and the guide rail, the elastic-contact hypothesis take into account the existence of contact patches between the bodies, and the location of the contact points is calculated using a simplified elastic method. In order to speed up the calculation, a multi-dimensional contact table is generated, enabling the use of simulation for Translohr tram running on curvatures with different radii.     

三种非赫兹滚动接触模型的对比研究

在轮轨损伤计算中,为了提高轮轨滚动接触解的求解效率与精度,常采用简化的非赫兹滚动接触模型.然而,此类模型的精度及适用性仍未得到充分的验证.以我国高速铁路常见的两种标准车轮型面(LMA和S1002CN)与标准CHN60钢轨的匹配状态为例,采用三种典型的非赫兹滚动接触简化模型(KP、STRIPES和ANALYN)进行模拟,...     

面-基层间接触条件对半刚性沥青混凝土路面极限轴载的影响

通过对典型结构的理论分析．探讨沥青混凝土面层与半刚性基层之间的接触条件对半刚性沥青混凝土路面极限轴载的影响。计算与分析显示：对于给定的路面结构．存在一个极限轴载;面—基层间接触条件对极限轴载有重要影响,层间条件从连续到滑动的变化可以导致极限轴载降低大约40％;路面极限轴载与现实超载车辆轴载处于同一量级,所讨论结构在不同的接触条件下的极限轴载在183～399kN之间变化;虽然在某种意义上有破坏,半刚性沥青混凝土路面在极限轴载作用后不一定丧失承载能力。     

铜镁合金接触线低周疲劳分析

通过采用不同塑性应变幅控制,对冷拔铜镁合金接触线进行室温低周疲劳试验．结果表明,随着循环周次的增加,发生循环软化现象．应力降低速率随着应变的降低而减缓．通过Manson-coffin公式估算出接触线用铜镁合金的低周疲劳寿命,得出应变-寿命关系,并指过渡寿命Nr,所在应变范围．     

层间接触条件对半刚性路面力学响应的影响分析

半刚性基层沥青路面为当前沥青路面的主要结构形式之一。以京津塘高速公路改扩建工程为依托,以壳牌设计软件BISAR3．0为计算工具,考虑层间光滑及层间连续两种层间接触条件,并用MATLAB7．0软件将各主要力学响应量进行三维化处理,对半刚性基层沥青路面在不同层间接触条件下的力学响应分布进行了全面的比较和分析。结果表明：当层间接触条件由完全光滑变为完全连续时,半刚性基层沥青路面的力学响应分布发生明显变化;与层问光滑条件下而言,层间连续条件下半刚性路面具有较明显的力学优势。     

半刚性路面层间实际结合状态的有限元模拟与分析

为了分析半刚性路面在层间实际结合状态下的应力及弯沉分布情况,同时为常规路面设计提供必要的校核手段,根据相关试验结果,利用通用有限元软件的接触模型来模拟路面的层间实际结合状态,并且考虑高温、超载等不利因素的影响,分析路面在层间实际结合状态、不利因素影响下的应力及弯沉变化情况。结果表明,利用有限元软件的接触模型对路面层间实际结合状态进行模拟是可行的,摩擦系数有条件时应根据实际试验结果确定,无条件时,可在0.6～0.8之间选取。     

参数变化对多元复合地基承载力发挥系数的影响

结合室内模型试验和理论研究成果,考虑土的弹塑性和桩、土接触的高度非线性行为,建立了比较合理的多元复合地基数值模型;通过改变设计参数(主桩桩径、次桩桩径、次桩桩长、主桩模量、次桩模量、褥垫层厚度、褥垫层模量),对多元复合地基承载力发挥系数作了较系统的研究,得出了有利于多元复合地基工程设计及理论研究的一些结论.     

渐开线直齿轮动态接触仿真分析

提出了利用ANSYS软件分析齿轮动态接触有限元仿真的实现方法,介绍了求解参数的确定以及算法的选择,计算了齿轮副在啮合过程中齿面接触应力的变化情况和分布规律。     

Family lifestyle factors related to children's congenital heart defects in China: a case-control study

Objective To explore the multiple risk factors for family lifestyle of children with congenital heart defects (CHDs) in Shaanxi Province, China. children and their parents. The univariate and multivariable logistic regression models were used to analyze the influence of risk factors related to parents' lifestyle on CHDs. Results Several possible risk factors were found for CHDs, including fever (OR=4.465, P=0.017), pesticides contact (OR=2.234, P=0.083), passive smoking during pregnancy (OR=20.529, P=0.007) and father's smoking (OR=3.342, P=0.005); fever (OR=2.428, P=0.012) and passive smoking during pregnancy (OR=1.201, P=0.037) were also correlated with ventricular sepal defect (VSD). Conclusion Fever, pesticides contact and passive smoking are associated with CHDs during pregnancy. We should focus our attention on health care during pregnancy to avoid the above-mentioned risk factors and call on parents to hold on to a good healthy lifestyle.     

浅析边坡稳定性分析的数值解

推导了坡面为两直线段斜坡的均质边坡稳定性安全系数函数式,利用遗传算法求出最危险滑弧位置、滑弧半径及相应的最小稳定性安全系数值,利用有限元法和接触摩擦弹簧元进行了边坡的渐进破坏分析,讨论了材料特性对边坡稳定性的影响。计算表明,渐进破坏分析所求出的稳定性安全系数比理论上求出的最小稳定性安全系数要小。