CAE软件操作小百科(12)

1 CAE软件与CAD软件接口问题在模型制作方面,CAD软件的功能远远强于CAE软件,因此,CAD软件与CAE软件之间的接口问题就显得比较重要.模型传递主要有2种方法:一种是通过专用数据接口进行传递,另一种是通过标     

基于模板的港口码头三维结构CAD/CAE 集成技术

针对港口码头结构CAD 几何模型生成CAE 单元模型,工程荷载CAD 模 型创建CAE 荷载模型,和CAE 分析结果与CAD 模型的关联关系等问题,利用模板的模型 独立性、规则性和可执行性等特性,研究了基于模板的港口码头三维结构CAD/CAE 集成技 术,定义了截面草图、三维实体和构件等多种CAD 建模模板,定义了机械草图和荷载等多 种荷载建模模板,定义了CAE 分析规则,实现了CAD 几何模型自动生成CAE 单元模型的 功能,定义了荷载转换规则,实现了工程荷载CAD 模型自动创建CAE 荷载模型的功能, 定义了整体模型模板,建立CAE 分析结果与CAD 模型的多对一关系,以此实现了港口码 头三维结构CAD/CAE 集成系统,大大提高了港口码头的设计效率,降低了设计人员的设计 难度,减少了设计错误。     

基于SimXpert实现ProE模型向CAE模型快速转化的模板开发

为实现CAD/CAE集成一体化设计,基于SimXpert开发ProE模型向CAE模型快速转化的模板系统.该系统通过特征命名的方式自动快速地进行CAD与CAE之间的信息传递,从而实现SimXpert模板对ProE模型的识别以及向有限元模型的转换.利用外部XML文件数据库对模型所需要的属性进行自动识别和创建,并对相应的部件赋予这些属性.CAD模型向CAE模型的流程式快速转化可以提高数值模拟的效率.     

基于CAE分析的网格模型的优化研究

注塑CAE常用的数值解法有边界单元法、有限单元法和有限差分法等,但这些解法都需要对所建立的模型进行单元网格划分,网格的好坏、疏密直接关系着CAE分析的效率.因此,网格模型的优化就成为CAE分析的一个关键环节. 一、几何模型的简化 由于软件功能的不同要求,注塑CAE模拟分析的网格模型往往与CAD设计的模型不完全一样,通常为了更为有效地进行模拟分析,在进行CAE的模型构建过程中,往往需要对模具的CAD模型中的一些细节进行简化运算.     

面向CAE 的网格模型特征简化与重建

针对CAE工程分析中网格模型的特点,提出了一种符合CAE特点的网格模型特征重建方法。鉴于CAD模型中的设计细节在CAE分析中可以忽略的特点,对CAD模型中的小圆角、倒角、小凸台等非结构性设计特征,采用基于面片法矢迭代滤波方法进行识别和滤除。算法首先识别出这些特征区域,然后根据非特征区域面片法矢调整特征区域法矢并更新顶点坐标,进行特征重建,最终得到符合CAE要求的网格模型。     

基于T-Spline的全自动几何拓扑修复方法

从高质量曲面网格生成的需求出发,提出了一种基于T-Spline的全自动几何拓扑修复方法.本文方法创新性主要可归纳为:1）对原有计算机辅助设计（Computer aided design,CAD）几何模型不进行任何修改保留其本真,自动识别CAD几何模型中常见不必要的几何特征,成功解决了CAD几何模型中存在的几何瑕疵,如短边、窄面、退化边、退化面、非连续光滑边界及尖锐特征等,利用新生成的"虚边"、"虚面"处理几何瑕疵,同时通过虚拓扑重构CAD几何模型的B-Rep;2）开发了一套CAD/CAE集成系统,统一了几何模型与计算分析模型,实现计算机辅助工程（Computer aided engineering,CAE）与CAD两者的无缝集成,所有拓扑修复操作及后续CAE分析计算均在同一环境下进行,避免了几何模型在CAE与CAD系统间进行转换时造成的数据丢失.该方法能够对复杂实体实现全自动几何拓扑修复及网格生成,实验表明,在保证不失真的前提下,修复后的几何模型能够生成质量良好的网格且能降低网格的生成规模,验证了本文方法的实用性和有效性,以满足工程实际分析的需要.     

面向CAE 的STL 模型三角网格均匀化

提出了一种基于STL数据的有限元网格再生成算法,该算法主要用于CAE工程分析.鉴于CAD模型的网格特征形态不匀称,分布不均匀的特点,对CAD模型进行网格再生成,使其符合CAE工程分析的要求.算法主要由拓扑建立、网格聚类、网格重采样和三角化四部分组成.实验表明该算法能够有效降低三角网格最长边和最短边的比值,使得模型的网格特征形态趋于均匀.     

CAD与CAE集成过程的分析与建模

文章较详细地分析了CAD产品设计与CAE产品工程分析的集成过程,用 IDEF0对该 CAD设计和CAE工程分析的集成过程进行了建模,所建立的IDEF0模型是建立 CAD、CAE集成信息模型的基础。     

Pro/E二次开发在模型检查技术中的应用

近年来,人们运用CAD/CAE的先进设计方法,提高了产品的设计质量,获得了显著的经济效益,但也逐渐认识到了它在应用中出现的各种问题.在利用有限元法分析结构空间尺寸复杂的产品时,需要将建好的CAD模型转换输出到CAE系统中,但数据传递过程中往往会出现各种问题,耗费用户巨大的时间和精力.本文为了能够顺利地进行有限元分析计算,从研究CAD/CAE模型转换出发,基于VC平台对Pro/E二次开发技术做了一定的探索研究,成功实现了模型转换前CAD模型的预先检查.     

创新性混合仿真平台--LMS Virtual.Lab

一、LMS Virtual.Lab简介 LMS Virtual.Lab是一个开放的环境,实现了与CAD、CAE和试验的无缝连接,它开放于领先的CAD系统(如CATIA、I-DEAS、UniGraphics和Pro/ENGINEER等),消除了CAD、CAE和试验之间的障碍,使工程师可以重复使用模型,而无需在每次应用时重新建模.     

Adaptive CAD model (re-)construction with THB-splines

Computer Aided Design (CAD) software libraries rely on the tensor-product NURBS model as standard spline technology. However, in applications of industrial complexity, this mathematical model does not provide sufficient flexibility as an effective geometric modeling option. In particular, the multivariate tensor-product construction precludes the design of adaptive spline representations that support local refinements. Consequently, many patches and trimming operations are needed in challenging applications. The investigation of generalizations of tensor-product splines that support adaptive refinement has recently gained significant momentum due to the advent of Isogeometric Analysis (IgA) [2], where adaptivity is needed for performing local refinement in numerical simulations. Moreover, traditional CAD models containing many small (and possibly trimmed) patches are not directly usable for IgA. Truncated hierarchical B-splines (THB-splines) provide the possibility of introducing different levels of resolution in an adaptive framework, while simultaneously preserving the main properties of standard B-splines. We demonstrate that surface fitting schemes based on THB-spline representations may lead to significant improvements for the geometric (re-)construction of critical turbine blade parts. Furthermore, the local THB-spline evaluation in terms of B-spline patches can be properly combined with commercial geometric modeling kernels in order to convert the multilevel spline representation into an equivalent – namely, exact – CAD geometry. This software interface fully integrates the adaptive modeling tool into CAD systems that comply with the current NURBS standard. It also paves the way for the introduction of isogeometric simulations into complex real world applications.     

An automated interface between CAD and CAM

The interface between CAD and CAM is an important phase in CAE (Computer Aided Engineering). There are many systems such as CAPP (Computer Aided Process Planning) that can solve this problem. But CAPP needs recognition of the features of a solid model that result from a complex procedure. This paper describes a new highly efficient method to link CAD and CAM from solid models to machinable models.     

GMCADS系统的研究及应用

当今,机械CAD向CAD/CAM/CAE集成化方向发展,机械系统运动学/动力学分析软件是集成化CAD/CAM/CAE不可缺少的支撑软件之一。我们以多刚体系统动力学为基本理论,研制了面向问题的、交互式的通用机械计算机辅助设计系统GMCADS。本文介绍了GMCADS系统的分析原理、图形输出技术,并给出了应用实例。     

Discontinuous Galerkin Based Isogeometric Analysis for Geometric Flows and Applications in Geometric Modeling

We propose a method which combines isogeometric analysis with the discontinuous Galerkin (DG) method for second and fourth order geometric flows to generate fairing surfaces, which are composed of multiple patches. This technique can be used to tackle a challenging problem in geometric modeling–gluing multi-patches together smoothly to create complex models. Non-uniform rational B-splines (NURBS), the most popular representations of geometric models developed in Computer Aided Design, are employed to describe the geometry and represent the numerical solution. Since NURBS basis functions over two different patches are independent, DG methods can be appropriately applied to glue the multiple patches together to obtain smooth solutions. We present semi-discrete DG schemes to solve the problem, and \(\mathcal {L}^{2}\)-stability is proved for the proposed schemes. Our method enjoys the following advantages. Firstly, the geometric flexibility of NURBS basis functions, especially the use of multiple patches, enable us to construct surface models with complex geometry and topology. Secondly, the constructed geometry is fair. Thirdly, since only the control points of the NURBS patches evolve in accordance with the geometric flows, and their number (degrees of freedom) is very small, our algorithm is very efficient. Finally, this method can be easily formulated and implemented. We apply the method in mean curvature flows and in quasi surface diffusion flows to solve various geometric modeling problems, such as minimal surface generation, surface blending and hole filling, etc. Examples are provided to illustrate the effectiveness of our method.     

Development of a multi-resolution framework for NUBS

The piecewise polynomial B-spline representation is a flexible tool in Computer Aided Geometric Design (CAGD) for representing and designing the geometric objects. In the field of Computer Graphics (CG), Computer Aided Design (CAD), or Computer Aided Engineering (CAE), a very useful property for a given spline model is to have locally supported basis functions. This allows localized modification of the shape. Unfortunately this property can also become a serious disadvantage when the user wishes to edit the global shape of a complex object. A multi-resolution representation is proposed as a solution to alleviate this problem.In this work, we propose a multi-resolution representation for Non-uniform B-splines (NUBS). The proposed multi-resolution model has three features that it uses control point decimation strategy for decomposing NUBS curves and it is efficient in both time and space utilization. A comparative study of the proposed work is also made with an alternate approach in the literature, which is based upon knot decimation.     

上海大众汽车覆盖件模具CAD/CAE/CAM系统

CAD／CAE／CAM技术在现代汽车模具设计和制造中具有重要作用。本文立足于上海大众汽车有限公司对车身覆盖件模具（CAI）／CAE／CAM系统的需求，论述了上海大众汽车覆盖件模具CAD／CAE／CAM系统的软硬件平和系统的结构体系。本文介绍的CAD／CAE／CAM系统已在上海大众的覆盖件模具设计制造和冲压工艺规划中开始应用，并取得苦于成果。     

CAD技术在工业设计中的应用

主要从产品造型、视觉传达和环境设计三方面讨论了计算机辅助设计(CAD)在工业设计中的广泛应用和巨大潜能,并指出目前的工业设计CAD软件系统在工业设计发展中所起的促进作用,最后论述了工业设计CAD的优点和发展趋势。