调整车身梁截面方向的系统研究

在车身结构概念设计阶段,需要对梁单元赋截面并调整截面的方向。研究了UG中调整截面方向的规律,设计了一种调整梁截面方向的工具。主要介绍了调整截面方向的方法：首先在UG的草图中建立简化的截面,利用坐标转换公式及形心公式计算主惯性轴,然后建立一个向量V控制草图中的截面方向,最后通过坐标变换得到空间调整截面方向的向量。利用此工具对某款轿车进行了分析,结果表明,采用此方法不仅大大提高了车身结构概念设计的效率,而且提高了设计的精度。     

基于MeshWorks和Optimus的白车身断面尺寸分析优化

为提高商用车车身前期设计阶段的开发效率,保证项目开发节点按时通过,在车身设计阶段引入参数化建模和联合仿真优化技术。基于MeshWorks软件对梁结构的整体宽度、翻边宽度、整体高度和板件厚度进行参数化建模,再通过Optimus软件搭建基于模态分析与刚度分析的优化流程,进行白车身轻量化设计。优化方案可减重14.6 kg,减重幅度5.1%,结构第1阶扭转频率提升4.4%,弯曲刚度提升2.8%,前端扭转刚度提升0.9%,后端扭转刚度提升1.5%。在性能小幅提升的情况下,车身轻量化效果明显。     

基于隐式参数化耦合模型的车身集成优化

为提高车身截面优化效率,基于SFE CONCEPT构建白车身关注部位的隐式参数化模型,并与白车身有限元非参数化模型进行耦合,使参数化模型与有限元模型耦合边界处的连接关系随截面变化自动更新,通过试验验证耦合模型的有效性。基于试验设计（design of experiments, DOE）方法、近似模型、多目标优化等策略,对白车身耦合模型进行刚度和模态等多学科集成优化,实现车身局部结构快速轻量化设计。     

基于概念设计的框架车身多目标优化系统

为实现概念设计阶段车身结构和性能的快速优化,构建多工况、多目标优化系统FVO,其中包括车身几何建模、有限元分析、结构优化等。该系统可以快速建立参数化框架车身几何模型,自动生成满足多工况要求的高精度有限元模型,利用多目标优化算法对车身的梁和板结构进行多工况优化计算,为用户提供满足众多约束条件的优化设计方案。在阐述FVO系统整体结构和具体方法的基础上,通过简单设计实例证明系统的有效性和准确性。     

白车身耐疲劳结构6σ稳健优化参数的估算仿真

为提高车辆耐疲劳结构性能,降低零部件失效概率,提出白车身耐疲劳结构6σ稳健优化参数估算方法.首先分析白车身耐疲劳结构组成部分及稳健优化,利用运动微方程描述其在线性条件下的相关向量,完成耐疲劳结构平均损耗的表达方程,将6σ稳健优化参数计算分解成4个基本步骤,以降低计算过程中不确定因素的敏感性;其次,以耐疲劳可用时间安全性要求为宗旨,计算出稳健优化参数的最大波动范围,利用2阶响应面模型计算均值及方差,完成估算模型的构建,使用遗传算法寻取最优结果;最终,与传统稳健优化参数方法的仿真结果对比证明,6σ稳健优化参数估算方法稳健性更高、抗干扰能力强,能有效提高车辆耐疲劳结构性能,改善零部件失效情况.     

基于多模型拓扑优化方法的车身结构概念设计

为获得最优的初始设计方案,在车身概念设计阶段对车身结构进行拓扑优化。车身结构性能指标综合考虑整体刚度、局部动态刚度和碰撞性能,采用多模型优化(multi-model optimization,MMO)方法解决此类复杂工况的拓扑优化问题,通过调节设计空间和设置参数,获得车身最优载荷路径。根据拓扑优化结果初步形成车身框架结构,可为后期详细设计提供参考。     

微型力敏操纵杆的结构优化设计

针对目前微型力敏操纵杆敏感元件封装难度大、操作手感僵硬等问题,进行结构优化设计。设计了一种柔性梁结构替代传统的刚性梁结构,该结构由弹性元件与柔性元件组成,其中弹性元件采用空心方形截面,增加了敏感元件的封装空间,以降低封装难度;柔性元件采用螺旋结构,能产生操作者易感知的拨动行程,改善操作手感。并提供了一种有效的计算方法,为柔性梁的具体参数设计提供依据。     

基于微悬臂梁的化学传感器的灵敏度研究

基于探测的原理,在动态模式下,首先对不同结构梁的本征频率偏移量进行了有限元分析,结果表明三角形梁的灵敏度最高。然后重点针对不同结构参数的三角形梁进行了动态计算,获得了其频率偏移量随结构参数变化的关系曲线。另外,通过静态模式下的有限元计算,发现各种梁自由端的偏移量相同,表明它们的静态灵敏度与形状无关。最后,对三角形梁在不同测量模式下结构参数的优化设计进行了分析。     

基于耐撞性的前纵梁截面优化设计

前纵梁是偏置碰撞测试中重要的吸能部件之一。本文对前纵梁截面形状进行了优化设计,以提高前纵梁的耐撞性。根据前纵梁截面尺寸参数得到设计变量,构建响应面模型,利用遗传算法计算得到优化结果。将优化所得的截面尺寸应用于某三厢轿车40%偏置碰撞分析中,结果表明,前纵梁耐撞性显著提高,碰撞侧B柱加速度峰值有效降低,整车被动安全性能得到提升。     

基于显式有限元技术的梁截面抗撞性优化

本文基于显式有限元技术,采用响应面法,以结构的比吸能为优化函数,以提高吸能原件的抗撞性为目的,对正方形截面的金属薄壁梁进行了形状优化．经过数值分析,得出了正方形截面梁的比吸能关于壁厚和截面边长的变化规律,这些规律可以用于实际吸能原件的设计,并为进一步研究奠定了基础．     

逆向工程中基于精确截面信息的曲面拟合*

针对带有精确截面信息的有序离散点的三维曲面重构问题,提出了一种NURBS曲面快速重构方法。该方法有效地减少了运算数据量,提高了运算效率,同时改进了传统曲面拟合在处理非均匀截面数据点时曲线曲面形状的失真和运算的不稳定现象,最后应用三维图形标准以及图形函数库在实际系统中验证了该方法的有效性。     

逆向工程中基于精确截面信息的曲面拟合

针对带有精确截面信息的有序离散点的三维曲面重构问题,提出了一种NURBS曲面快速重构方法．该方法有效地减少了运算数据量,提高了运算效率,同时改进了传统曲面拟合在处理非均匀截面数据点时曲线曲面形状的失真和运算的不稳定现象,最后应用三维图形标准以及图形函数库在实际系统中验证了该方法的有效性．     

基于图像的香烟滤棒截面周长检测系统

在香烟生产中,滤棒形状尺寸的好坏直接影响到香烟的生产质量和效率;针对传统形状尺寸检测技术的缺点,提出了基于图像的香烟滤棒截面周长检测系统;考虑到在生产中香烟滤棒易变形,其截面不一定为标准圆,不能通过测量其直径来求得周长;采用多边形近似法得到截面周长;仿真试验结果表明了系统的可行性。     

S-57电子海图文件基础处理库的设计实现

国际海道测量组织制定的S-57标准是目前电子海图文件的主要国际标准,S-57数据集文件的处理是电子海图显示与信息系统的基础。在分析S-57标准理论数据模型、数据结构和产品规范的基础上,用C++实现了一套S-57数据集文件基础处理程序库,其功能包括目录文件、基础数据文件和改正数据文件的读取、数据改正以及物标信息解析。本库能完整地保持S-57文件的数据信息,较好地保持数据的原始逻辑结构,能提取物标完整的几何信息,获取物标的属性/类目信息。本库与具体的用户数据结构、用户文件格式无关,具备一定的通用性,可用于电子海图应用系统的底层开发。     

Mapping 2D midship drawings into a 3D ship hull model based on STEP AP218

Standard for the exchange of product model data (STEP) AP218 has a standard schema to represent the structural model of a midship section. While its schema facilitate the exchange of ship structural models among heterogeneous systems, most shipyards and classification societies exchange information using 2D paper drawings. We propose a feature parameter input method to generate a 3D STEP model of a ship structure from 2D drawings. We have analyzed the ship structure information contained in 2D drawings and have defined a data model to express the contents of the drawing. We also developed a GUI for the feature parameter input. To translate 2D information extracted from the drawing into a STEP AP218 model, we have developed a shape generation library and have generated the 3D ship model through this library. The generated 3D STEP model of a ship structure can be used to exchange information between design departments in a shipyard as well as between classification societies and shipyards.     

轨道车辆新型组合结构吸能装置耐碰撞性分析

为保证列车碰撞时车体次要部位或附加装置尽可能多地吸收撞击能量,减少财产损失和人员伤亡,提出组合结构吸能装置的设计思想.根据耐撞性车体吸能装置设计原理,设计出不同截面形状管的组合结构吸能装置.利用ANSYS/LS-DYNA对其分别进行动态仿真,研究其吸能特性,并取其最优方案与试验结果进行对比,从而验证仿真模型的正确性.通过对原始设计方案外箱板的截面形状和吸能管的端部结构加以改进,设计出两种新型的组合结构吸能装置.仿真分析结果表明,结构的截面形状对整个装置的吸能特性有较大影响,改变结构的截面形状可以有效调节碰撞界面力峰值和均值载荷,改进后的吸能装置耐撞性综合指标更优。     

Shape recognition and pose estimation for mobile Augmented Reality

Nestor is a real-time recognition and camera pose estimation system for planar shapes. The system allows shapes that carry contextual meanings for humans to be used as Augmented Reality (AR) tracking targets. The user can teach the system new shapes in real time. New shapes can be shown to the system frontally, or they can be automatically rectified according to previously learned shapes. Shapes can be automatically assigned virtual content by classification according to a shape class library. Nestor performs shape recognition by analyzing contour structures and generating projective-invariant signatures from their concavities. The concavities are further used to extract features for pose estimation and tracking. Pose refinement is carried out by minimizing the reprojection error between sample points on each image contour and its library counterpart. Sample points are matched by evolving an active contour in real time. Our experiments show that the system provides stable and accurate registration, and runs at interactive frame rates on a Nokia N95 mobile phone.     

基于C/S体系结构的一卡通局域网管理系统

以C/S体系结构为基础，设计并实现了企业一卡通网络管理系统，对其中包括餐厅，超市等消费场所管理，图书馆管理系统及其基本Web的查询，以及网吧计时管理系统等各子系统的功能进行了分析，提出各功能模块的设计方案，实践证明该系统运行可靠。     

A hybrid system approach for supporting digital libraries

A digital library (DL) consists of a database which contains library information and a user interface which provides a visual window for users to search relevant information stored in the database. Thus, an abstract structure of a digital library can be defined as a combination of a special purpose database and a user-friendly interface. This paper addresses one of the fundamental aspects of such a combination. This is the formal data structure for linking an object oriented database with hypermedia to support digital libraries. It is important to establish a formal structure for a digital library in order to efficiently maintain different types of library information. This article discusses how to build an object oriented hybrid system to support digital libraries. In particular, we focus on the discussion of a general purpose data model for digital libraries and the design of the corresponding hypermedia interface. The significant features of this research are, first, a formalized data model to define a digital library system structure; second, a practical approach to manage the global schema of a library system; and finally, a design strategy to integrate hypermedia with databases to support a wide range of application areas. Received: 15 December 1997 / Revised: June 1999     

Flexible manufacturing of sheet metal parts based on digitized-die

Digitized-die forming (DDF) is a flexible manufacturing technology through which a variety of three-dimensional sheet metal parts can be produced in a DDF system. It eliminates the need to design and produce the conventional die. The central component of DDF system is a pair of matrices of punches, the punches are controlled by computer and the desired shape of die is constructed by changing the heights of punches. Based on the flexibility of DDF, new forming processes are designed that cannot be realized in conventional stamping. In varying deformation path DDF, a sheet part is manufactured along an optimal forming path, and large deformation can be achieved for the material with poor formability. In sectional DDF, a sheet part is formed section by section, and this technique makes it possible to manufacture large-size parts in a small DDF press. A closed-loop forming system was built by combining DDF with rapid 3D-shape measurement system. It is used to compensate for material springback and improve dimensional accuracy of the formed part. And a DDF system with multi-point blankholder control system was developed to control the material flow, thereby to prevent sheet parts from wrinkling and tearing. The DDF integrated system is described, and the detailed forming procedures are explained in the paper. Typical examples are presented showing the applicability of the DDF technology.