应用有限元法研究车架结构的耐撞性

本文应用有限地对车辆正面碰撞过程中车架结构的大变形过程进行了计算机模拟。文中介绍了非线性有限元分析的基本方程，运用微机版ＤＹＮＡ３Ｄ软件，在合理简化的基础上，建立了车呆结构的有限元模型，通过计算机模拟，预测了车辆正碰过程中车架的变形位置和变形形式。针对存在的问题，对车架结构进行了改进设计。实车碰撞试验表明：改进后，车架结构的耐撞性有明显提高。     

自主水下航行器制导系统的设计

简要介绍了某小型远程自主水下航行器制导系统的设计要求和软硬件实现方法,该制导系统已成功应用于211工程建设的自主水下航行器上。     

基于正则化与B样条曲线的桥梁影响线识别方法

为了快速评估既有桥梁的安全性，研究了基于多源实测信息快速准确识别桥梁影响线的方法。首先利用桥梁动力响应及车辆移动的实测信息，建立影响线识别的数学模型。在模型中引入Tikhonov正则化方法以解决病态矩阵求解问题，通过设置罚函数项以取得较光滑并贴近真实的影响线。然后通过基函数扩展法重构影响线，将其表示为一系列三次B样条基函数的线性组合，从而将问题从识别众多影响线因子简化为识别少量基函数权重系数。为了验证上述方法的可行性，先在实验室模拟钢制试验小车在钢筋混凝土三跨连续梁模型上移动的过程。基于实测布置于梁底的多测点挠度和应变响应时程以及相应的试验车信息，可识别出不同位置测点的挠度和应变影响线。试验结果表明无论是影响线的总体形状还是局部峰值，识别解与基准解均能较好地吻合。该方法还被进一步应用到一座简支现浇预应力混凝土箱梁桥。该试验通过实测检测车过桥期间的桥梁跨中截面若干测点的动应变、动挠度以及车辆重力、实时位置等信息，准确识别了对应于不同车道的挠度和应变影响线。通过对比桥梁静载实测和影响线虚拟加载结果，发现两者偏差绝对值在5%以内。在一定程度上表明了该影响线识别方法具有较高精度，并具备工程应用的良好潜力。     

Parallel computing with domain decomposition for the vehicle crashworthiness simulation

The research presented in the paper deals with explicit nonlinear finite element calculation with domain decomposition for vehicle crashworthiness simulation. This is very important for vehicle design. Parallel computing is an efficient solution method to speedup and enhance the solving ability of large-scale numerical simulation. In this paper, a cost-effective domain decomposition method based on contact balance is presented, and the algorithm flowchart including contact computing is provided, and the parallel computing process and communication overhead are analyzed. Furthermore, scalability of the parallel computing method on different hardware platforms, the SGI Onyx 3800 and the ShenWei cluster, is studied. Finally, the effect of different domain decomposition strategy on vehicle crashworthiness simulation computing efficiency is presented. To end users, the research results should provide a reference for vehicle design and choosing appropriate hardware platform and computing software.     

桥梁构件养护编码与快速识别方法

为了便于桥梁养护与管理,提高桥梁精细化管养的水平,在分析国内外相关行业的信息分级与编码体系的基础上,结合桥梁属性和养护特点,提出了桥梁构件养护编码与快速识别方法,制定了精确到构件级的分级编码结构和分类代码。据此,基于二维码应用设计了桥梁构件智能信息标签,采用APP扫描信息标签的方式对桥梁构件进行识别,初步建立了一套适用于桥梁构件养护编码与快速识别方法。应用结果表明,该方法能建立全面、统一和精确到设施构件级的身份标识并能快速识别桥梁构件,为桥梁全生命周期养护管理奠定基础,极大提升了桥梁养护效率和质量。     

Understanding the limitations of different vehicle models for roll dynamics studies

An accurate and realistic vehicle model is essential for the development of effective vehicle control systems. Many different vehicle models have been developed for use in various vehicle control systems. The complexity of these models and the assumptions made in their development depend on their application. This article looks into the development and validity of vehicle models for prediction of roll behavior and their suitability for application in roll control systems. A 14 DOF vehicle model that includes dynamics of roll center and nonlinear effects due to vehicle geometry changes is developed. The limitations, validity of simplified equations, and various modeling assumptions are discussed by analyzing their effect on the model roll responses in various vehicle maneuvers. A formulation of the popular 8 DOF vehicle model that gives good correlation with the 14 DOF model is presented. The possible limitations of the 14 DOF model compared with an actual vehicle are also discussed.     

A substitute model of two-dimensional dry friction exposed to dither generated by rolling contact of wheel and rail

Dither generated by rolling contact of wheel and rail smoothes dry friction damping provided by the primary suspension dampers of freight wagons and it should be taken into account in numerical simulations. But numerically the problem is non-smooth and this leads to long execution time during simulation, especially when the vehicle with friction dampers is modelled in the environment of an multi-body system simulation program, whose solver has to cope with many strong non-linearities. The other difficulty is the necessity of handling within the code a number of big volume files of recorded dither sampled with high frequency. To avoid these difficulties, a substitute model of two-dimensional dry friction exposed to dither is proposed that does not need application of dither during simulation, but it behaves as if dither were applied. Due to this property of the model, the excitation of the vehicle model by track irregularities may be supplied as low-frequency input, which allows fast execution and, the necessity of handling high-volume files of recorded dither is avoided. The substitute model is numerically effective. To identify parameters of the substitute model, a pre-processing employing a sample of the realistic dither is carried-out on a simple two-degrees-of-freedom system. The substitute model is anisotropic, describing anisotropic properties of the two-dimensional friction arising in the presence of one-dimensional dither. The model may be applied in other branches of engineering, for example, in mechatronics and robotics, where application of dither may improve the accuracy of positioning devices.     

基于卷积型小波包变换的船用水位调节器故障辨识

以某型蒸汽船的主冷凝器水位调节器为研究对象,应用卷积型小波包变换提取各种故障信号分解后的相对小波包能量,建立水位调节器标准故障库,并引进Euclidean空间距离公式作为判据进行故障识别。实验结果表明,该方法可以对水位调节器的典型故障进行快速、正确分类,降低了其故障定位与维修的盲目性。     

船载AIS设备在应用中存在的主要问题

AIS（船舶自动识别系统）在安装使用中存在着不足急需改进。笔者结合船舶检验工作，对一些具有代表性的问题进行了论述并提出了解决办法和建议。