钢管混凝土拱桥在车辆荷载作用下的非线性动力响应分析

根据随动硬化理论和钢管混凝土组合材料恢复力模型 ,提出了复杂应力状态下钢管混凝土组合材料的弹塑性应力应变关系。采用非线性有限元法 ,对一钢管混凝土拱桥进行移动车辆荷载作用下车—桥体系的动力响应分析 ,并进一步研究钢管混凝土组合材料进入塑性后对体系振动的影响 ,取得了较满意的结果 ,为钢管混凝土拱桥动力性能评价提供参考。     

车门开闭耐久仿真分析研究及优化

针对在车门开闭耐久试验过程中,某样车车门出现的焊点疲劳开裂问题,在考虑铰链连接、密封条连接及焊点细化建模的前提下,建立车门开闭耐久仿真有限元模型;根据Miner线性疲劳累计损伤理论,对车门开闭模型进行疲劳仿真分析,找出结构设计的风险点。在此基础上,提出优化方案,进行仿真疲劳寿命预测,最终通过试验验证了优化方案的有效性。提出了一种针对车门开闭耐久试验中焊点开裂的疲劳分析优化方法,可以在产品设计开发阶段,准确地发现问题并快速解决问题,可以缩短开发周期,节省开发费用,具有一定的工程实用价值。     

Automotive window seal design considering external aerodynamic load and surrogate constraint modeling

Installed between metallic DIW (Door in White) panel and nonmetallic door glass, automotive window seals has great influence on customers’ perception of NVH (Noise-Vibration-Harshness) performance. Recently, aerodynamic effect on ride comfort attracts increasing research interest. The external load causes unsteady pressure on glass, which is finally transferred to window seals and leads to complicated vibration and increases interior noise level. However, non-linearities of hyper-elastic material, rubber-glass contact and large deformation behavior make the construction of window seals constraint model much more difficult, thus impeding further analysis and optimization. A new window seal design method is proposed featuring in considering aerodynamics-induced load and nonlinear constraint. Firstly, by SST ? k ? ε (Shear Stress Transport) turbulence model, external flow field of full-scale automotive is established by solving three-dimensional, steady and uncompressible Navier-Stokes equation. With re-exploited mapping algorithm, the overall aerodynamic pressure is extracted and matched to local window as external loads for seals, thus taking into account high speed fluid-structure interaction. Secondly, based on functional equivalence and mathematical fitting, new surrogate constraint model is presented. The unitedseal CLD (Compression Load Deflection) curve is synthesized after translations and transformations from two semi-seal CLD experimental measurements of inner and outer lips. It is then fit to complex exponential function, making seal constraint equivalent to a surrogate elastic constraint with variable stiffness. Experiment is performed to verify the constraint surrogation effectiveness. Finally, case study of window seal design under high speed is investigated. After seal optimization based on the new method, windows seals’ maximal displacements have decreased. The improved seal-glass fitting status shows better NVH quality of window seal in high-speed condition.     

On the interest of integrating vehicle dynamics for the ground propagation of vibrations: the case of urban railway traffic

This paper presents a complete numerical model for studying the vertical dynamics of the vehicle/track interaction and its impact on the surrounding soil, with the emphasis on vehicle modelling. A decoupling between the track and the soil is proposed, due to the difficulty of considering all the subsystem components. The train/track model is based on a multibody model (for the vehicle) and a finite element model (for the track). The soil is modelled using an infinite/finite element approach. Simulations of both models are carried out in the time domain, which is better able to simulate the propagation of the vibration waves and to take into account the possible nonlinearity of a component. The methodology is applied in the case of an urban tram track and validated with the available experimental data. Models for the tram, the track and the soil are described. Results from the complete model of the vehicle and a simple model, based on an axle load, are compared with experimental results and the benefits of a complete model in the simulation of the ground vibration propagation induced by railway vehicles are demonstrated. Moreover, a parametric study of the vehicle wheel type is conducted, which shows the advantage of a resilient wheel, for various rail defects.     

从LS-DYNA到PAM-CRASH的模型转换及侧面碰撞仿真

研究了有限元模型从LS-DYNA向PAM-CRASH的转换方法,利用该方法成功实现了某轿车整车模型的转换。在转换模型的基础上,通过加入车门内饰、假人和移动障碍壁模型,建立了完整的整车侧面碰撞模型。将仿真计算结果和整车试验测试数据进行比较,验证了模型的有效性。     

Near surface deformation of rails and wheels in a curve and during acceleration and braking

A hierarchical concept for describing the rolling/sliding contact of a wheel on a rail is proposed, which is developed to model the near surface deformation of the contacting partners depending on the vehicle system dynamics. In principal the vehicle dynamics simulation delivers the input for a static finite element model for the elastic-plastic rolling/sliding contact investigation. To include also more realistic rough surfaces in the calculations, which is absolutely necessary to predict the highly deformed surface layer as observed in wheels and rails, a further refinement of the mesh is necessary and performed. The output values of the static finite element model are now boundary conditions for the finite element micro-model. The results of this micro-model correspond well with the micro-structural investigations of wheel and rail surfaces.     

Experimental and numerical investigation of the effect of rail corrugation on the behaviour of rail fastenings

This paper presents the results of a detailed investigation of the effects of rail corrugation on the dynamic behaviour of metro rail fastenings, obtained from extensive experiments conducted on site and from simulations of train–track dynamics. The results of tests conducted with a metro train operating on corrugated tracks are presented and discussed first. A three-dimensional (3D) model of the metro train and a slab track was developed using multi-body dynamics modelling and the finite element method to simulate the effect of rail corrugation on the dynamic behaviour of rail fastenings. In the model, the metro train is modelled as a multi-rigid body system, and the slab track is modelled as a discrete elastic support system consisting of two Timoshenko beams for the rails, a 3D solid finite element (FE) model for the slabs, periodic discrete viscoelastic elements for the rail fastenings that connect the rails to the slabs, and uniformly viscoelastic elements for the subgrade beneath the slabs. The proposed train–track model was used to investigate the effects of rail corrugation on the dynamic behaviour of the metro track system and fastenings. An FE model for the rail fastenings was also developed and was used to calculate the stresses in the clips, some of which rupture under the excitation of rail corrugation. The results of the field experiments and dynamics simulations provide an insight into the root causes of the fracture of the clips, and several remedies are suggested for mitigating strong vibrations and failure of metro rail fastening systems.     

车内低频振动噪声的虚拟传递路径分析

传递路径分析法是诊断汽车振动噪声问题准确有效的方法。试验传递路径分析耗时耗力且需要实制样车,为在整车开发初期诊断汽车振动噪声问题,对整车虚拟传递路径分析法进行了研究。首先建立了包含底盘的整车声固耦合有限元模型,采用频率响应法预测车内声学振动响应,发现驾驶员右耳声压在38 Hz处以及驾驶员座椅导轨振动在59 Hz处存在较大峰值。在有限元模型基础上建立了整车虚拟传递路径分析模型,该模型合成的声学振动结果与频率响应法结果吻合较好,验证了模型的正确性。利用虚拟传递路径法对两处峰值作诊断分析,根据分析结果对贡献量大的路径进行优化。优化结果表明,38 Hz处驾驶员右耳声压降低2 dB,59 Hz处座椅振动改善效果明显。     

采用预变形车门的侧面碰撞台车试验

鉴于车门在碰撞假人时已有一定的变形,提出用预变形车门取代原车门来模拟侧面碰撞的方案以提高模拟精度,预变形车门从模拟过程的中间结果导出。以采用此法获得的对应30ms和50ms时的预变形车门模型,分别进行模拟。计算结果的对比分析表明,采用30ms预变形车门模拟结果比较接近原车试验结果。最后以此模型制作实物预变形车门,进行了台车试验验证。     

基于模型修正梁格法的车桥耦合振动分析系统

首先以一座钢桁架连续梁桥为工程实例,建立尽可能考虑结构特点的初始有限元模型,并结合现场试验采集的静、动力实测数据,建立考虑变形、频率及振型等静、动力信息的多目标函数,通过有限元模型修正获得能够反映结构真实状态的基准有限元模型;其次介绍了梁格法桥梁车桥耦合振动分析模块以及静载试验整车加载模块编制思路,并嵌入自行研发的桥梁结构动力分析软件BDANS;最后将修正后的有限元模型输入至自行研发的梁格法车桥静动力分析模块,并将静动力荷载工况下的实测响应、BDANS计算值与通用软件ANSYS计算值三者进行了相互校核和对比。结果表明:BDANS静力分析模块的计算结果与ANSYS静力计算结果完全吻合,BDANS动力分析模块在不同行车工况下的动力计算响应趋势与实测响应趋势保持一致,从而验证了该分析模块的可靠性。     

浅谈商用车门框胶条密封性的改进方案

本文通过对商用车门框胶条漏水原因的分析,简要介绍如何从门框胶条的结构设计进行改善,进而改善商用车胶条的密封性能,为解决商用车门框胶条漏水问题提供理论支持。     

某车型侧围异常振动分析与改善

针对某车型在侧滑门关闭和行驶过程中,车身侧围振动明显过大的现象进行试验和CAE分析.找到了侧围振动过大的根源,并采取相应改进措施,将振动幅值降低到了主观评价可以接受的水平.     

基于Marc的汽车车门密封条有限元分析

汽车车门密封条结构直接影响关门力。针对某车型背门关闭时出现的关门力过大现象,建立该密封条模型,运用非线性有限元分析软件Marc对密封条截面进行压缩负荷分析,并对其截面进行结构优化,降低了背门密封条的压缩负荷。     

四轮转向电动汽车车架的设计与有限元分析

现有电动汽车底盘普遍为在传统汽车的基础上进行的改进,不能很好的适应电动汽车特有的结构,为更好的实现四轮转向的功能,重新设计了适合四轮转向电动汽车的车架。应用三维软件SolidWorks,通过整车虚拟装配确定了合理的四轮转向电动汽车的车架结构,进而建立了车架的三维模型。运用有限元分析理论,将模型导入Ansys Workbench软件后,建立了车架的有限元模型,对车架在弯曲和扭转工况下的静态结构性能进行了分析,得出相应工况下的应力和应变大小;还进行了模态分析,避免了共振。在满足强度和刚度的条件下对车架结构进行了改进,并通过焊接加工得到了适合四轮转向电动汽车的车架,对以后电动汽车底盘的改进设计提供了参考。     

高水压大直径盾构主轴承2种主流密封性能对比研究

为提高大直径盾构（≥9 m）主轴承密封承压能力及可靠性和安全性，通过研究主流形式大直径盾构主轴承密封结构、工作原理、性能参数及典型案例，对2种形式主轴承密封接触应力进行有限元分析，并对比分析数十台2种主轴承密封保压试验数据和掘进数据。研究表明： 1）带楔形突起的唇形密封结构比不带楔形突起的唇形密封结构承压能力更强，且在不借助压力补偿系统时可承受≤0.6 MPa的开挖舱压力。2）在开挖舱压力＞0.6 MPa或开挖舱压力瞬间波动较大的工况下，压力补偿系统由于人为操作迟滞或响应不及时等不确定性因素，唇形密封系统存在较大被击穿的安全隐患。3）单道指形密封正面最大动态承压能力为1 MPa，建议开挖舱压力在0.4～1 MPa时选用指形密封，不需要配置压力补偿系统，可提高主轴承密封结构的承压和稳压能力。     

车身板件结构对汽车行车舒适性的影响

采用有限元与多体动力学相结合的方法分析了车身板件对振动的影响,改变车身板件局部结构,在对振动影响最大的前后地板上增加加强筋后对整车进行振动响应模拟,揭示了车身板件结构对汽车在路面激励下行车舒适性的影响。分析表明,在地板上增加加强筋可以极大地提高汽车的行车舒适性。     

Investigation on dynamical interaction between a heavy vehicle and road pavement

This paper presents a model for three-dimensional, heavy vehicle-pavement-foundation coupled system, which is modelled as a seven-DOF vehicle moving along a simply supported double-layer rectangular thin plate on a linear viscoelastic foundation. The vertical tyre force is described by a single point-contact model, while the pavement-foundation is modelled as a double-layer plate on a linear viscoelastic foundation. Using the Galerkin method and quick direct integral method, the dynamical behaviour of the vehicle-pavement-foundation coupled system is investigated numerically and compared with that of traditional vehicle system and pavement system. The effects of coupling action on vehicle body vertical acceleration, suspension deformations, tyre forces and pavement displacements are also obtained. The investigation shows that the coupling action could not be neglected even on a smooth road surface, such as highway. Thus, it is necessary to investigate the dynamics of vehicle and pavement simultaneously based on the vehicle-pavement-foundation coupled system.     

侧门碰撞中车门自动解锁现象的改进

我国侧面碰撞安全法规和新车评价体系都对侧面碰撞提出了“在碰撞过程中车门不得开启”的要求。文章对某车型开发过程中出现的后门开启问题进行了深入分析和研究,通过在侧碰分析模型中加入门锁系统有限元模型,找出了门把手区域在碰撞时发生过大的翻转是导致后门开启的原因。根据该原因,提出了门外板上部加强件下延以及门把手下部增加贴片的改进方案,成功解决了门锁开启的问题。通过研究可以得出：在侧面碰撞分析模型中建立详细的门锁系统的模型,不仅能更准确地模拟侧门的变形,而且能很好地发现和解决门锁的自动解锁问题。     

汽车仪表板与转向系振动特性CAE分析

基于给定的某款车型数据,利用MSC．ADAMS／Car平台建立包括仪表板和转向系在内刚柔耦合整车模型,对转向系和仪表板进行典型工况下NVH特性分析;并利用有限元方法对仪表板、转向系总成建模并求解模态参数,有效预测可能出现的NVH问题,为提升整车NVH性能提供了必要的参考。     

全FRP车行桥梁结构设计与分析

提出了一种由蜂窝桥面板和U型主梁组合而成的新型全GFRP桥梁结构,并建立全桥有限元模型开展公路荷载作用下的力学性能分析。结果表明:桥梁结构的自振频率和振型、正常使用状态的竖向位移、极限承载能力状态的GFRP材料应力和粘结界面剪应力均满足规范要求。该结构形式具有构造简单、受力合理、施工方便的特点,有望在全FRP车行桥梁中推广应用。