共查询到20条相似文献,搜索用时 140 毫秒
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长期以来 ,对CAD/CAM集成的研究都是以特征技术为核心。大多数传统特征造型系统都具有设计特征库。这些特征库往往被冠以参数化特征库名称 ,但是库中的特征模式却没有提供真正的参数化特征。本文提出了一种真正的参数化设计特征库 ,包括库中特征模式的表示方法及库中特征模式的参数化驱动方法 ,本文称为概念性B Rep(BoundaryRepresentaion)。概念性B Rep是产品模型生成过程与结果表示中所存在的所有实体的表示方法 ,其中包括设计特征库中的基本形状特征模式。设计特征库中的特征模式在被给予具体参数后形成的实体即设计特征引用前的表示形式、加工特征的实体部分、产品模型的整体实体部分 ,均由概念性B Rep表示 相似文献
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面向加工的三维实体数字化建模技术 总被引:1,自引:0,他引:1
介绍了一套面向加工的三维实体数字化建模技术 ,该技术的应用可以实现 :根据三维实体的原始测量数据 ,在进行三维刀具半径补偿的基础上 ,建立被测实体的数字化模型。该模型非常有助于生成对被测实体进行加工的数控程序。文中重点介绍了一系列数据处理方法 ,解决了测量和加工一体化系统中的关键问题。 相似文献
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李海生 《机械工程与自动化》2008,(2):72-73
针对有限元数值分析,应用Pro/E软件对某V型柴油机机体进行三维实体建模,对建模方法和建模过程给予描述,为下一步三维实体有限元分析提供合理的几何模型. 相似文献
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Tianyang Dong Ling Zhang Ruofeng Tong Jinxiang Dong 《The International Journal of Advanced Manufacturing Technology》2006,30(5-6):507-520
An important aspect of design for the life cycle is assessing the disassemblability of products. This paper presents a novel approach to automatic generation of disassembly sequence from hierarchical attributed liaison graph (HALG) representation of an assembly through recursively decomposing the assembly into subassemblies. In order to increase the planning efficiency, the HALG is built according to the knowledge in engineering, design and demanufacturing domains. In this method, the boundary representation (B-Rep) models are simplified by removing the hidden surfaces to reduce the computational complexity of disassembly planning. For each layer of HALG, the subassembly selection indices defined in terms of mobility, stability, and parallelism are proposed to evaluate the extracted tentative subassemblies and select the preferred subassemblies. To verify the validity and efficiency of the approach, a variety of assemblies including some complicated products are tested, and the corresponding results are presented. 相似文献
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圆柱体相贯线上的圆角表示法是CAD和计算机辅助设计中众所周知的难题。所有的CAD/CAM软件中都没有这一功能。本文借助"滚球法",以二次圆弧曲线的NURBS生成原理为基础,利用NURBS方法可精确表示圆及圆弧的特点,给出了构造圆柱体相贯线上圆角过渡曲面的实用算法,同时给出了过渡曲面的NURBS表示。 相似文献
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阐述了三维实体图形从CATIA V4文件格式转换成CATIA V5文件格式后,图形出现的一些变化,并介绍了怎样对转换后的图形进行编辑和修改,使其与CATIA V4中的图形保持一致而不失真. 相似文献
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基于最优匹配的三维CAD模型相似性评价算法 总被引:2,自引:0,他引:2
提出一种基于最优匹配的三维计算机辅助设计模型相似性评价算法.根据三维计算机辅助设计模型的边界表示,将相比较的两个计算机辅助设计模型拆分成面,并分别对面进行分类.将两模型中同种类型的面两两匹配,运用相应的准则计算出每对面的相似性系数δij,从而使同种类型的面形成了一个二分图.利用图论中二分图的最优匹配算法,计算出两个模型同类型面中各面的最优匹配方案,并计算出加权最优匹配值,最后将各种类型面的最优匹配值相加得到模型的相似系数,以此作为评价模型相似性的依据.为恰当地评价两个类型相同面的相似性,给出了能够综合反映面几何特征和拓扑特征的评价准则.试验表明本方法能够客观地反映两计算机辅助设计模型的相似程度,并较好地反映人视觉上的相似经验. 相似文献
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提出了一种新的基于层片数据的等成分轮廓线/面的FGM实体模型与成形路径规划方法.将材料信息与零件几何模型分层后得到的层片文件相关联,之后在层片内将连续材料分布离散成等成分轮廓线/面,以等成分轮廓线/面为单元进行路径规划,较现有方法简便、效率高,用于FGM火车车轮等离子熔积直接成形的路径规划. 相似文献
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General three-dimensional image simulation and surface reconstruction in scanning probe microscopy using a dexel representation 总被引:1,自引:0,他引:1
The ability to image complex general three-dimensional (3D) structures, including reentrant surfaces and undercut features using scanning probe microscopy, is becoming increasing important in many small length-scale applications. This paper presents a dexel data representation and its algorithm implementation for scanning probe microscope (SPM) image simulation (morphological dilation) and surface reconstruction (erosion) on such general 3D structures. Validation using simulations, some of which are modeled upon actual atomic force microscope data, demonstrates that the dexel representation can efficiently simulate SPM imaging and reconstruct the sample surface from measured images, including those with reentrant surfaces and undercut features. 相似文献
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This paper presents a simple and effective method for reconstructing 3D bio-CAD models from a sequence of computer tomography
(CT) medical image data. In this work, a heterogeneous implicit solid representation method is proposed to describe a heterogeneous
model of the human body. The use of implicit solid as a basis for 3D bio-CAD models facilitates the robustness and simplification
of the process for converting CT images to a 3D bio-CAD model. An almost perfect 3D bio-CAD model is achieved from implicit
solid interpolation combined with domain decomposition. The implicit solid is defined by a radial basis function which is
a continuous scalar-value function over the domain R
3. The generated solid consists of the set of all points at which this scalar function value is the Houndsfield unit (HU) value
obtained from the CT image. CT images of human bone were used as the case studies for the reconstruction of the 3D solid model
from CT scan data. Experimental results show that the proposed method has the potential to represent internal human body details
accurately and efficiently suitable for rapid prototyping, finite element analysis, and tissue engineering. 相似文献
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采用VisualBasic编程语言工具,对三维造型软件SolidEdge进行二次开发,实现了对塑料管材挤出机头的主要零件参数化设计。按照用户选择或输入的不同参数,得到不同尺寸零件的三维实体和相应的变量表,扩展了SolidEdge的功能。 相似文献
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Tool path generation by offsetting curves on polyhedral surfaces based on mesh flattening 总被引:1,自引:0,他引:1
Jinting Xu Yuwen Sun Shunke Wang 《The International Journal of Advanced Manufacturing Technology》2013,64(9-12):1201-1212
Polyhedral surfaces are used as representation model for CAM and process planning purposes because of its simplicity for data exchange and geometric computation. However, there are few tool path planning strategies for such surfaces but isoplanar method. This paper presents a contour offset approach to tool path generation for three-axis ball-end milling of polyhedral surfaces, based on a novel method for offsetting curves on polyhedral surfaces. One of its salient features is to reduce the task of removing complex interfering of offsets from 3D physical surfaces to 2D plane by flattening mesh surfaces and avoid costly 3D Boolean set operations and relatively expensive distance calculation. Moreover, in practical implement, the procedures of calculating offset points and removing interfering loops are merged and carried out simultaneously results in an efficient tool path generation method. Empirical examples illustrate the feasibility of the proposed method. 相似文献