空调客车围护结构隔热设计方案比较研究

利用数值分析的方法，分析了空调客车非稳态情况下四种结构车厢体的二维温度场分布，计算了车厢体的二维传热损失和热桥附加传热损失。在骨架和内衬之间加一层隔热组织改善了车的隔热特性，为客车围护结构隔热优化提供了依据。     

全承载式车身结构浅析

简要说明了客车全承载车身技术的重要性和全承载车身的优越性；阐述了全承载车身的发展历程和在我国的应用现状，最后详细说明了全承载车身结构的特点及优点，使我们对于全承载车身结构技术有了一个更全面的认识。     

基于工作过程系统化的汽车车身修复技术课程设计

本文以基于工作过程系统化思想,对汽车车身修复技术课程进行了设计.阐述了本课程基于工作过程系统化的课程设计思路、学习情境设计、课程教学方法及考核方法设计.     

Hydroelastic analysis of oblique irregular waves with a pontoon-type VLFS edged with dual inclined perforated plates

The fluid-structure interaction of oblique irregular waves with a pontoon-type very large floating structure (VLFS) edged with dual horizontal/inclined perforated plates has been investigated in the context of the direct time domain modal expansion theory. For the hydroelastic analysis, the boundary element method (BEM) based on time domain Kelvin sources is implemented to establish water wave model including the viscous effect of the perforated plates through the Darcy’s law, and the finite element method (FEM) is adopted for solving the deflections of the VLFS modeled as an equivalent Mindlin thick plate. In order to enhance the computing efficiency, the interpolation-tabulation scheme is applied to assess rapidly and accurately the free-surface Green function and its partial derivatives in finite water depth, and the boundary integral equation of a half or quarter VLFS model is further established taking advantage of symmetry of flow field and structure. Also, the numerical solutions are validated against a series of experimental tests. In the comparison, the empirical relationship between the actual porosity and porous parameter is successfully applied. Numerical solutions and model tests are executed to determine the hydroelastic response characteristics of VLFS with an attached anti-motion device. This study examines the effects of porosity, submerged depth, inclined angle and gap distance of such dual perforated anti-motion plates on the hydroelastic response to provide information regarding the optimal design. The effects of oblique wave angle on the performance of anti-motion and hydroelastic behavior of VLFS are also emphatically examined.     

Time-domain coupled dynamic simulation for SFT-mooring-train interaction in waves and earthquakes

In this study, Submerged Floating Tunnel (SFT)-mooring-train coupled dynamics is solved in the time domain to investigate their dynamic and hydro-elastic interactions under wave and earthquake excitations. The SFT is modeled by the rod-FE (finite element) theory, and it is connected to mooring lines through dummy-connection-mass and linear and rotational springs. A 3D rigid-multi-body dynamic model is developed for train dynamics that consists of seven rigid bodies. The tunnel-train interaction is taken into consideration based on the wheel-rail correspondence assumption and the simplified Kalker linear creep theory. The developed computer simulation program is validated through comparisons with commercial programs and published results when possible. In the case of earthquake-induced dynamics of the coupled system, the effects of soil conditions, tunnel length, mooring interval, seismic-wave propagation, and seaquake are investigated. The magnitudes of the SFT downward motions induced by the moving train are small compared with the motions induced by earthquakes. The earthquake causes transient SFT responses especially at their lowest wet natural frequencies while high-frequency motions are induced by seaquake effect. Structural damping and seismic propagation play an important role in dynamic responses. The interaction of the tunnel and moving train is also evaluated for various train speeds in terms of the derailment and offload factors and riding-comfort criterion. For the given SFT and train designs, the offload factor and riding-comfort criterion can slightly exceed their limits at certain earthquake conditions with the speed as high as 70 m/s, which can be adjusted by reducing train speed.     

导电密封胶对不锈钢车体电阻点焊焊接性能影响研究

分析了电阻点焊原理,对相同的点焊搭接方式,分别采用3种工况进行焊接试验。3种工况分别采用相同焊接参数对搭接接触面涂导电密封胶和不涂导电密封胶的试件进行焊接;优化焊接参数后,对搭接接触面涂导电密封胶的试验件进行焊接。对3种工况下完成的焊接试件进行拉伸力检测试验、金相熔核尺寸检测和缺陷检测试验,对熔核直径、拉伸力、熔核内部缺陷的试验结果进行分析。试验结果表明:导电密封胶对电阻点焊的焊接性能存在影响;通过适当优化焊接参数,可以提高涂导电密封胶试件的焊接性能,焊接质量能够满足产品焊接要求。     

水中悬浮隧道交通荷载模拟方法研究

为研究水中悬浮隧道交通荷载的合理模拟方法以及交通荷载对隧道结构的影响,借鉴铁路、公路交通荷载的模拟方法,综合考虑车辆轮载、路面不平度、行车速度以及外部激励荷载等影响因素的共同作用,提出水中悬浮隧道交通荷载的模拟表达式。通过数值模拟计算,分析悬浮隧道交通荷载的变化特征,并研究不同交通荷载模拟方法对悬浮隧道结构振动位移响应的影响。结果表明:文章提出的交通荷载模拟方法计算结果符合移动振动荷载的波动性和周期性特征。在对结构振动位移响应影响方面,固定均布荷载相当于静载,移动集中荷载和移动振动荷载时的位移变化幅值相对固定均布荷载时的大且影响相似,但移动振动荷载时的振幅稍大,体现了交通荷载中动荷载部分对结构振动位移响应的影响,更适合用来模拟悬浮隧道中的交通荷载。     

基于地基回弹因素的盾构隧道管片上浮预测

针对软弱地层盾构隧道管片脱出盾尾后出现的上浮问题,分析盾构施工过程中管片上浮的诱因,得出软弱地层中管片的上浮主要是地层应力重分布产生的地基回弹力引起的。在此基础上建立隧道开挖动态模型,分析隧道上浮量变化规律以及地层特性对管片上浮量的影响规律,得出地层弹性模量和管片上浮量呈一定的指数关系,且弹性模量对管片上浮量的影响远大于地层黏聚力和内摩擦角。通过力平衡理论计算盾构开挖引起的地层回弹力、管片上浮量以及隧道上浮影响的地层高度范围,并通过对珠江狮子洋工程管片上浮量的计算与实测对比,证明该公式的合理性,为盾构隧道工程中考虑地基抗力引起的管片上浮量预测提供一种新的方法。     

采用变化基本体的授课方法以提高教学效果

在《机械（工程）制图》教学中,学生对基本体的变化及其在实际中的应用难以理解,文中介绍提高基本体教学效果的方法。     

不锈钢地铁车辆侧墙焊缝缺陷率分析

由于非熔透型激光叠焊工艺的局限性,侧墙焊缝处会产生内外钢板局部未焊透的现象即焊缝缺陷.为研究这种焊缝在不同缺陷率下的拉剪强度及其对车体静强度的影响,结合某不锈钢地铁车辆激光焊车体,通过建立不同焊缝缺陷率的车体有限元模型,分析各个工况下不同焊缝缺陷率的车体侧墙焊缝剪应力的变化,以此确定在静载工况下不锈钢激光焊车体侧墙焊缝缺陷率的限值.