ObjectARX应用程序开发中AcBr与AcGe类库的应用

介绍了在AutoCADObjectARX应用程序开发中 ,如何利用AcBr与AcGe类库来访问和提取零件三维实体模型上的实体和子实体的几何信息 ,举例说明了这两类库在特征建模系统开发中的应用技术     

ObjectARX应用程序开发中AcBrcGe类库的应用

介绍了在AutoCADObjectARX应用程序开发中，如何利用AcBr与AcGe类库来访问和提取零件三维实体模型上的实体和子实体的几何信息，举例说明了这两类库在特征建模系统开发中的应用技术。     

基于圆角特征简化的工序三维几何建模方法

三维实体模型是CAX集成研究中的基础,圆角特征广泛存在于零件设计模型中,为提高此类零件工序三维几何建模的准确性,提出一种基于圆角特征简化的工序几何建模方法.通过分析工序三维几何建模过程中对圆角特征几何元素的提取过程,提出构建圆角特征线段,以便准确获取三维模型上的加工特征边界;利用加工特征边界和拉伸、旋转和扫掠3种常用的几何造型方式,建立加工体积特征;通过上一道工序的三维模型与加工体积特征作布尔差运算,得到本工序的三维几何模型.最后以某零件的工序三维几何建模过程为例,采用3种方法进行工序几何建模,通过对结果的分析对比,验证了文中方法的优越性.     

基于三维实体模型的钢结构工业厂房CAD/CAM软件后处理系统

为提高钢结构工业厂房设计的准确性、精确度和工作效率,为某钢结构工业厂房CAD/CAM软件研制出基于三维实体模型的后处理系统.该系统基于面向对象的编程技术,抽象出描述实际结构零件几何信息、结构特征和设计条件的智能型实体对象.将对象以及对象之间的层次关系和逻辑关系存储在AutoCAD图形数据库中,形成三维实体模型,用于直观、准确和完整地表现具有复杂空间关系和细部构造的真实结构;实现数据库对象的建立、编辑、查询、显示和数据整理等操作.该系统结合具体结构形式的特点,实现用于施工图设计和深化设计的全部关键功能.     

SOLIDWORKS 2015制作麻花钻头模型

麻花钻是应用非常广泛的孔加工用具,同时也是几何形状复杂的切削刀具。要使用三维软件创建出麻花钻的实体模型,不仅要了解麻花钻的结构、参数等相关知识,还要掌握三维软件实体建模的技术。本文以SOLIDWORKS 2015作为建模工具,介绍其三维实体的建模过程。     

基于三视图的实体重建技术研究

基于三视图的三维实体重建技术是根据已有二维视图中的几何信息和拓扑信息,生成相应的三维实体模型.以AutoCAD绘制的三视图及DXF格式的文件信息为基础,提出并实现了一种由三视图重建三维实体的算法.通过对三视图的规则处理,由计算机自动实现实体重建,对三视图分别进行平移、旋转、拉伸操作,然后作相应的布尔运算即可反求出该视图...     

渐开线齿轮实体建模与模板研究

基于Pro/ENGINEER的参数化设计,是指先用一组参数定义零件的三维实体模型并确定参数关系,包含几何关系和拓扑关系,然后提供给设计人员进行零件三维造型使用,设计结果的修改由尺寸驱动.设计时不必考虑零件中几何元素的准确位置或数值,而是通过向图形添加适当的约束条件定义零件形状.零件的参数化模型就是带有参数名的草绘,用户通过编辑参数,零件几何模型的拓扑信息不变,而尺寸自动改变.每一个约束形成一个代数关系式,通过约束推理确定需要修改的尺寸参数,系统将自动检索此尺寸参数对应的数据结构,找出相关参数的方程组并计算出参数,驱动参数化模型形状的改变,从而形成新的零件三维实体模型.     

高效的实体模型布尔操作

三维实体几何造型是实现产品设计、分析以及加工的集成化CAD／CAM系统的几何基础。利用实体模型不仅可以方便产品的三维形状设计,同时还可以进行产品的分析工作,如物性计算、有限元分析     

用CATIA设计结构清晰的实体零件

对于实体几何造型来说，不同的构造过程虽然可以构造出同样的实体零件，但其造型过程及实体的构型结构（结构树）却直接影响到实体模型的稳定性、可修改性、可理解性及实体的应用。一个好的实体零件的结构树应为：（１）其结构树应是低而平缓的树结构，可以提高拼合运算的速度，提高实体模型的稳定性和可靠性，优化零件的修改和更新（Ｕｐｄａｔｅ）性能；（２）避免在体素或特征之间的非法和多余的操作；（３）能够反映零件的结构和构造特点体素或特征的合理组合，可充分反映零件的结构和构造特点，提高零件的可理解性及可修改性；（４）可…     

基于实体模型的产品形状特征识别

依据实体造型的特点,从模型空间的特征层入手,搜寻模型空间中的简单形状特征,并根据造型特点获取单个特征在零件模型上的几何拓扑关系,从而实现形状特征的自动识别.通过分析特征实体造型,提出一种基于实体模型的产品形状特征识别方法,并结合微波器件产品开发特征参数提取模块,实现复杂零件模型形状特征的自动识别与提取.该方法为快速建立企业零件库提供途径,也为网络环境下的协同设计和数据共享奠定基础.     

Development of a semantic product modeling system for initial hull structure in shipbuilding

In the initial stage of ship design, designers represent geometry, arrangement, and dimension of hull structures, which correspond to product model information, with 2D geometric primitives such as points, lines, arcs, and drawing symbols on 2D drawings. However, designers must translate the product model information defined on the 2D drawings more intelligently in the following design stages. Thus, design semantics could be lost and design processes that follow could be delayed because of errors by mistranslating the information. Here, design semantics mean design intents of the designer, that is, functions and structures which the product must have.In this study, a semantic product model data structure of an initial ship hull structure was proposed, and a semantic product modeling system was developed based on the proposed data structure. The proposed data structure can store semantic product model information such as product design results with the use of 2D wire frame geometrical data, part attributes, and design knowledge. Hence, this information can be used to generate a 3D solid model and production material information for CAPP as needed.The applicability of the proposed data structure and the developed system was verified by applying them to the deadweight 300,000 ton of Very Large Crude oil Carrier’s product modeling procedure. The application results showed that the proposed data structure and the developed system can be efficiently used for overall initial ship design environment.     

Identifying and constructing elemental parts of shafts based on conditional random fields model

Semantic information is very important for understanding 2D engineering drawings. However, this kind of information is implicit so that it is hard to be extracted and understood by computers. In this paper, we aim to identify the semantic information of shafts from their 2D drawings, and then reconstruct the 3D models. The 2D representations of shafts are diverse. By analyzing the characteristics of 2D drawings of shafts, we find that there is always a view which represents the projected outline of the shaft, and each loop in this view corresponds to an elemental part. The conditional random fields (CRFs) model is a classification technique which can automatically integrate various features, rather than manually organizing of heuristic rules. We first use a CRFs model to identify elemental parts with semantic information. The 3D elemental parts are then constructed by a parameters template method. Compared with the existing 3D reconstruction methods, our approach can obtain both geometrical information and semantic information of each part of shafts from 2D drawings. Several examples are provided to demonstrate that our algorithm can accurately handle diverse 2D drawings of shafts.     

CAD modeling for the components made of multi heterogeneous materials and smart materials

There appear more critical requirements for special functions of components/products in various areas, which can be satisfied only by using heterogeneous materials and/or smart materials. The heterogeneous materials include composite materials, functionally graded materials, and heterogeneous materials with a periodic microstructure. To design and manufacture the components made of these materials, the computer models for representing them need first to be built so that further analysis, optimization and manufacturing can be implemented based on the models. This paper develops such a modeling method, which can be implemented by employing the functions of current CAD graphic software and obtain the model that includes all the material information (about periodic microstructures, constituent composition, inclusions, and embedded parts) along with geometry information in 3D solid modeling without the problem arising from too much data.     

建筑结构平面图辅助设计系统VHAutoFraming的设计与实现

VHAutoFraming使用面向对象的参数化褓造型方法，结合建筑图的自动理解，设计了从三维到二维的正向工作流程；充分利用三维实体数据的完整性，实现各层次二维图形的自动生成和结构力学分析所需的数据模型的自动建立；并提供简明的交互方式，辅助结构设计师方便、快速、准确地设计和绘制结构平面图。     

A single solution method for converting 2D assembly drawings to 3D part drawings

Although solid models play a central role in modern CAD systems, 2D CAD systems are still commonly used for designing products without complex curved faces. Therefore, an important task is to convert 2D drawings to solid models, and this is usually carried out manually even in present CAD systems. Many methods have been proposed to automatically convert orthographic part drawings of solid objects to solid models. Unfortunately, products are usually drawn as 2D assembly drawings, and therefore, these methods cannot be applied. A further problem is the difficult and time-consuming task of decomposing 2D assembly drawings into 2D part drawings. In previous work, the authors proposed a method to automatically decompose 2D assembly drawings into 3D part drawings, from which 2D part drawings can be easily generated. However, one problem with the proposed method was that the number of solutions could easily explode if the 2D assembly drawings became complex. Building on this work, here we describe a new method to automatically convert 2D assembly drawings to 3D part drawings, generating a unique solution for designers regardless of the complexity of the original 2D assembly drawings. The only requirement for the approach is that the assembly drawings consist of standard parts such as bars and plates. In 2D assembly drawings, the dimensions, part numbers and parts lists are usually drawn, and the proposed method utilizes these to obtain a unique solution.     

生土结构住宅建筑CAD软件开发

为合理地设计生土结构住宅,基于AutoCAD图形平台,开发一套用于单层生土住宅的结构设计软件.软件采用交互式的参数化方式建立结构三维实体模型,整合屋盖体系计算分析、构件规范验算和自动化施工图生成等功能.软件建模方便,操作步骤简单,能完成一般生土结构住宅的设计、计算和绘图.     

钢结构节点三维实体技术

针对钢结构节点设计和施工图绘制需要大量构造细节的问题,应用钢结构节点的三维实体技术,研发相应的钢结构后处理系统.采用模板的概念与方法表达各种形式的钢结构节点,用三维实体技术构造钢结构节点及构件的三维计算机模型.该系统作为钢结构专业CAD软件3D3S的核心技术已经成功应用于数千项实际工程的施工详图设计中,实用性很强.     

Identifying faces in a 2D line drawing representing a manifold object

A straightforward way to illustrate a 3D model is to use a line drawing. Faces in a 2D line drawing provide important information for reconstructing its 3D geometry. Manifold objects belong to a class of common solids and most solid systems are based on manifold geometry. In this paper, a new method is proposed for finding faces from single 2D line drawings representing manifolds. The face identification is formulated based on a property of manifolds: each edge of a manifold is shared exactly by two faces. The two main steps in our method are (1) searching for cycles from a line drawing and (2) searching for faces from the cycles. In order to speed up the face identification procedure, a number of properties, most of which relate to planar manifold geometry in line drawings, are presented to identify most of the cycles that are or are not real faces in a drawing, thus reducing the number of unknown cycles in the second searching. Schemes to deal with manifolds with curved faces and manifolds each represented by two or more disjoint graphs are also proposed. The experimental results show that our method can handle manifolds previous methods can handle, as well as those they cannot.     

基于 MBD 的三维图样表达方式研究与系统实现

针对现有三维图样技术在实际应用中存在的主要问题,提出了设计视图、模型与 标注分区显示、集成标注等具体方法,解决了目前三维图样信息显示不清晰、无法满足复杂产 品信息定义需求等关键问题。结合数字化环境下产品信息表达与数据一致性等需求,采用信息 结构树保证了几何与非几何信息间的关联性。给出了三维图样系统的具体设计方案,以及相应 可视化功能的具体实现方法,实现了基于 ACIS 与 HOOPS 联合平台的三维图样软件系统开发, 在该系统中完成了典型零件的精度设计,验证了三维图样软件系统的实用性。