The role of the contact geometry in wheel–rail impact due to wheel flats: Part II

A classification of wheel flats according to the different stages of their growth is given, along with the characteristic features of the dynamic wheel–rail interaction for each category. Mathematical expressions and frequency spectra of the corresponding wheel mass trajectories are derived. Difference is made between the subcritical and the transcritical speed regime. A criterion is derived for contact loss for worn flats. Simulations show that the dynamic wheel–rail interaction is governed by the track stiffness for low train speeds or long flat lengths; for high speeds and/or short flat lengths the interaction is governed by the inertial properties of the wheel and the rail. For a given flat geometry, nonlinearities in the relationship between the impact magnitude and the train speed occur in the stiffness-dominated speed domain, whereas this relationship is approximately linear in the inertia-governed domain. In the latter domain, the impact magnitude is found to be linearly dependent upon the maximum trajectorial curvature or inversely linearly dependent on the minimum circumferential wheel tread curvature. The above relationships are valid for the subcritical speed regime, in which no contact loss occurs. Different contributions from the literature are compared with respect to the established relationship between impact magnitude and speed. Significant differences are found, due to insufficiently defined parameters and conditions. Conditions are derived for a consistent application of the so-called equivalent rail indentation in experiments with wheel flats, and the indirect strain registration method for measuring dynamic wheel–rail contact forces is reviewed.     

客车前后顶三维造型设计及模型模具制作

简述利用UG软件进行客车前后顶的三维造型设计模型制作和模具翻制。     

某围垦区市政工程软基处理措施初探

该文结合某围垦工程实例,提出围垦区市政工程软基处理的设计思路,并针对该垦区的工程实际,提出适用该类土质的软基处理方法,供工程技术人员参考。     

顺应区域社会改革发展需要,培养应用型英语专业人才

在珠江三角洲地区改革发展规划纲要的指导下,应积极进行英语专业人才培养模式的改革与实践。通过分析应用型英语人才所需的知识、素质和能力,提出我院英语专业的培养目标和专业特色,倡导以服务地方经济发展为目标,培养面向21世纪的应用型英语人才。     

高职国际航运业务管理专业分方向教学模式探索

根据国际航运市场的发展与需求和高职教育教学的实际情况,提出通过改变国际航运业务管理专业传统的专业教育模式,探索新的专业教育模式,对学生的情况进行分专业方向教学,培养与单位的实际需求零距离的航运人才,确保各专业方向的学生在毕业以后能够找到理想的工作,保证就业率和就业质量。     

高速铁路卵石掺拌粉煤灰改良路基填料试验研究

哈尔滨至大连客运专线沿线距离长,不少地段路基填料匮乏,为了降低工程成本,保护自然环境,针对部分区段内卵石料源丰富、废弃粉煤灰数量较大的情况,进行了在原河卵石填料中掺加细粒土和粉煤灰的方式以改善填料级配、使之成为合格的路基填筑材料的研究。为了探讨该方案的可行性,文中分别对配制试样进行了级配试验、击实试验和现场压实检测试验,在现场压实试验过程中分别采取不同的压实方法以探讨科学合理的压实工艺。工艺试验的测试结果表明,这种改良方式改善了填料的颗粒级配,有效提高了路基的强度和密实度,能够使填料满足规范要求,不但具有明显的经济效益,还具有较强的社会效益和环保效益。     

既有双线提高旅客列车速度对起停附加时分及追踪列车间隔的影响

将旅客列车速度提高到１４０￣１６０ｋｍ／ｈ是铁路改善旅客运输质量、参与市场竞争的重要手段，是铁路面临的新课题。本文对既有双线自动闭塞区段提高旅客列车速度并相应提高货物列车速度后旅客列车起停附加时分及货物列车起停附加时分的变化进行了分析和讨论，进而对旅客列车提高速度后的列车追踪间隔时间Ｉ追、列车到达间隔时间Ｉ到、列车出发间隔时间Ｉ发和列车不停车通过车站间隔时间Ｉ通的变化情况进行了较为详细的分析，得出     

高速列车运用检修及动车段的设计研究

论述了高速列车在运用检修中的若干个基本问题。阐明了高速列车具有全新的运用检修模式；提出了高速列车的运行方式，乘务制度检修制度工艺流程，以及高速动车组配属数量，检修工作量，检修库线，库车线的设计计算方法与计算公式，给了了高速动力段主检修库厂房结构的推荐方案。     

A linear complementarity method for the solution of vertical vehicle–track interaction

A new method is proposed for the solution of the vertical vehicle–track interaction including a separation between wheel and rail. The vehicle is modelled as a multi-body system using rigid bodies, and the track is treated as a three-layer beam model in which the rail is considered as an Euler-Bernoulli beam and both the sleepers and the ballast are represented by lumped masses. A linear complementarity formulation is directly established using a combination of the wheel–rail normal contact condition and the generalised-α method. This linear complementarity problem is solved using the Lemke algorithm, and the wheel–rail contact force can be obtained. Then the dynamic responses of the vehicle and the track are solved without iteration based on the generalised-α method. The same equations of motion for the vehicle and track are adopted at the different wheel–rail contact situations. This method can remove some restrictions, that is, time-dependent mass, damping and stiffness matrices of the coupled system, multiple equations of motion for the different contact situations and the effect of the contact stiffness. Numerical results demonstrate that the proposed method is effective for simulating the vehicle–track interaction including a separation between wheel and rail.     

Physical processes in wheel–rail contact and its implications on vehicle–track interaction

Friction within the wheel–rail contact highly influences all aspects of vehicle–track interaction. Models describing this frictional behaviour are of high relevance, for example, for reliable predictions on drive train dynamics. It has been shown by experiments, that the friction at a certain position on rail is not describable by only one number for the coefficient of friction. Beside the contact conditions (existence of liquids, solid third bodies, etc.) the vehicle speed, normal loading and contact geometry are further influencing factors. State-of-the-art models are not able to account for this sufficiently. Thus, an Extended-Creep-Force-Model was developed taking into account effects from third body layers. This model is able to describe all considered effects. In this way, a significant improvement of the prediction quality with respect to all aspects of vehicle–track interaction is expected.