Design of the database for CAD based on group technology

An important part of integrated CAD/CAPP/CAM is represented by the database in which all the information and data relevant for the design, planning and manufacturing of a component are available to the designer. The database must thus include relevant data about the geometrical primitives, materials, surfaces, tolerances, etc.This paper reports on the design of a database to be used in CAD/CAPP/CAM with particular reference to GT principles. The data required in the CAD process are strongly structured, so that their computer representation actually yields a structural model of the component. The elements which form the component model are parameterized shape primitives generating the matrix of the primitives for forming rotational and non-rotational components. The organization of their data and the communication between the designer and the database are discussed in detail. In this context a solution is proposed which enables the designer not only to draft a component by means of a computer, but, at the same time, to classify the component into a part family using a pattern recognition method for computer-aided GT classification.     

Selecting and evaluating CAD systems

This article discusses some of the factors to be considered when selecting and evaluating systems for CAD (computer-aided design). An operative CAD system is one which performs a particular design function (application) by employing software running on suitable hardware.

Although the selection of an application of software and of hardware, are usually interdependant, they are treated separately within the article. The first two sections are concerned with identifying design problems which are suitable for the application of CAD. These sections are followed by a summary of the factors to be considered in choosing software and hardware. The final sections discuss the costing and economics of CAD systems.     

An integrated intelligent machining system for axisymmetric parts using PC-based CAD and CAM software packages

Machining process planning involves the formation of a set of directions describing the machining operations required to transform raw stock into a finished part. Conventional process planning, performed manually, relies on the knowledge and competence of an experienced process planner and tends to be time consuming and error prone. In the past two decades, much effort has been spent on improving process planning by utilizing the power of a computer to emulate the capabilities of an experienced planner. During the same period, computer-aided design (CAD) and computer-aided manufacturing (CAM) software has been developed to enhance design productivity and to assist the NC code generation facets of the machining process. The entire planning process may be automated be integrating CAD and CAM using computer-aided process planing (CAPP). The research described in this paper outlines the design and development of an intelligent CAPP system integrating two commercial CAD and CAM software packages, Autocad and Mastercam.     

Development of a CAD-based intelligent manufacturing system

This research proposes a CAD-based manufacturing system that embraces computer-aided design, design for manufacturing and assembly (DFMA), computer-aided process planning (CAPP), computer-aided assembly planning (CAAP), and vision-robot integration. The proposed system starts with the design of products using a commercial CAD software, Autocad. The design data is then extracted from the CAD database and organized into a standardized product model. Interface programs are used to translate the geometrical and topological information in the model into DFMA, CAPP, CAAP and vision image representations. Based on the results generated by the interface programs the applications using artificial intelligence techniques can automatically generate redesign advises, CNC part programs, assembly sequence and instructions for robots.     

Structural optimization with CADO method for a three-dimensional sheet-metal vehicle body

The aim of this study is to increase power/weight ratio of a steel-alloyed vehicle body without any structural weakness and to use an integrated engineering solution of “computer-aided design, engineering and optimization (CADO)”. In this optimization study, primarily the body's “computer-aided design (CAD)” parametric model has been prepared for some static analyses are essential for the design study. In the following step, some critical dimensions of the structure's parts have been defined as design parameters. The goal of the optimization study is a minimization of critical equivalent stress value is under the yield limit. In addition, a sensitivity study has been made on the body model with stress measures for an in-depth analysis. In various steps, Pro/Engineer CAD and Pro/MECHANICA computer-aided engineering (CAE) software has been used. Finally, the obtained results have been presented as both visually and in diagrams or tables. In other words, this study can be defined as a computer-aided design and optimization application of a sophisticated three-dimensional (3D) sheet-metal structural model. Consequently, for the solution of a sophisticated structural design problem, it has been seen that integrated CAD/CAE programs supported optimization techniques are vital much more proper to provide the time, error and cost reduction compared to classical design processes, can be given as contributes of this study to previous literature.     

Toward an intelligent CAD-CMM interface

Current links between computer-aided design (CAD) and automatic inspection systems such as coordinate measuring machines (CMMs) often rely on intelligence provided by the user. The possibility of introducing an intelligent link between a CAD system and a CMM is considered. Problem areas when dealing with 2.5-dimensional components are discussed and some potential solutions, which have been tested, are given.     

Web-based learning in the computer-aided design curriculum

Abstract This study attempts to apply the principle of constructivism and virtual reality (VR) technologies to computer-aided design (CAD) curriculum by integrating network, CAD and VR into a web-based learning environment. Through VR technologies, it is expected that the traditional two-dimensional (2D) computer graphics course can be expanded into a three-dimensional (3D) real-time simulation one. VR technologies provide a novel method to enhance user visualisation of complex three-dimensional graphics and environments. Experience and environmental interaction allow users more readily to perceive the dimensional interrelations of graphics which are typically portrayed through static multiview or pictorial representations. A web-based learning system ( WebDeGrator ) has been developed to simulate a computer graphics learning system for learning. Future developments of the proposed web-based learning framework are also discussed.     

Cad-induced changes in design work

CAD systems are a new aid for design processes that can be used to solve both simple and complex tasks. Sometimes, it is possible to perform tasks, such as the dynamic simulation of movement and finite element analysis, which could not have been done without the aid of computers. But, even the ability of the computer to perform less time-consuming tasks leads to changes in design activities. Advances in design methodologies and organization have been made, leading to better fulfillment of functions, better manufacturing-oriented design, and better scheduling of design and manufacture. Using computers for design, new design processes have become possible due to the computational speed and large storage capacity of modern computers, and to advances in software. The process of merging conventional and computer-aided design processes for a new computer-aided design technology is not finished: a methodology based on CAD still has to be developed. This paper will explain some developments in CAD systems that are changing the design activities. The aim of CAD systems development is to change the need for the designer to work within the limited possibilities of today's CAD systems. In the new systems, support will be easier and the information will be better integrated so that they can better serve the design demands.     

“实例+项目”作为《建筑CAD》标准教学法的探讨

AutoCAD是一种广泛应用的计算机辅助设计软件,广泛应用于多行业,当然也成为了各类院校教学的基本课程。在开设建筑类专业的院校,建筑CAD是学生必修的课程,是学生应掌握的一种基本技能,但作为课程的教师却参差不一,教学水平各异,所以我们应探索出一套行之有效的教学方法供广大教学者参考,形成一套建筑CAD的标准教学法:实例+项目教学法。     

Computer-aided design method for the components made of heterogeneous materials

With rapid developments of high-tech in various fields, there appear more critical requirements for special functions of components/products, which can be satisfied only by using heterogeneous materials: composite materials, functionally graded materials, or heterogeneous materials with a periodic microstructure. However, currently there exists no systematic and effective method for designing components made of these heterogeneous materials. This paper develops such a computer-aided design method, under the guide of Axiomatic Design, which can apply the functions of current CAD/CAE software. With the design method, all the information about both configuration and materials of a heterogeneous component, needed for creating its CAD model, can be obtained.     

Reflections on using a UIMS for complex applications

The building of a user interface management system (UIMS) is described from the perspective of the development team. This UIMS is a key component of the open-architecture system-integration services (OASIS) project at Electronic Data Systems. While OASIS's application domain is generally CAD/CAM/CAE (computer-aided design/manufacturing/engineering), users can extend its functionality by using a command macro language. The results are presented as observations and impressions gathered from the programming and training staffs, users, UIMS developers     

Surgical and interventional robotics: part III [Tutorial]

Part I of this tutorial described two broad paradigms of interventional assistance: surgical computer-aided design (CAD)/computer-aided manufacturing (CAM) and surgical assistance. Part II focused on the underlying concepts of surgical CAD/CAM, with a particular emphasis on percutaneous procedures. This final installment of our three-part tutorial series discusses surgical assistance. In this section, we introduce the basic concepts of a surgical workstation and briefly review several core robotic technologies used in surgicalworkstations     

An open platform of shape design optimization for shell structure

A general platform built on a computer-aided design (CAD) system is developed for parameterized shape design optimization of shell structure. Within the platform, parameterized surface modeling and computer-aided engineering (CAE) applications are embedded and seamlessly integrated with the CAD system through its application programming interface (API). Firstly, instead of the CAD system inherent surface modeling, a parameterized surface modeling for shell structure is fulfilled through integrating with parametric solid modeling of the CAD system. Thus, any dimensions for parametric solid modeling can be used to control shape modification of shell structure and serve as design variables for shape design optimization. Secondly, seamless integration of geometry modeling and finite-element modeling for shell structure is implemented. Finally, with integrated procedures of finite-element analysis and optimization algorithms, a general platform for parameterized shape optimization of shell structure is realized. Numerical examples are presented, and the results validate the effectiveness and efficiency of the platform. A shorten version of this paper was presented to the 7th World Congress of Computation Mechanics (WCCM 2006), July 16–22, 2006, Los Angeles, CA, USA.     

Enhancing CAD-based shape optimisation by automatically updating the CAD model’s parameterisation

Structural and Multidisciplinary Optimization - This paper presents an approach which increases the flexibility of a computer-aided design (CAD) model by automatically refining its parameterization...     

A novel CACD/CAD/CAE integrated design framework for fiber-reinforced plastic parts

This work presents a novel CACD/CAD/CAE integrated framework for design, modeling, and optimization of fiber-reinforced plastic parts, which can greatly enhance the current design practice by realizing partial automation and multi-stage optimization. To support this framework, a new heterogeneous feature model (HFM) has been developed to model the fiber-reinforced objects and to be transferred between engineering modules. To be specific, the CACD (computer-aided conceptual design) module employs the level-set structure and material optimization to produce the initial design with thickness control, and also the initial HFM; the CAD (computer-aided design) module allows manual editing on the HFM to reflect various design intents; then, the injection molding CAE (computer-aided engineering) simulates the manufacturing process, and the response surface method (RSM) is applied to optimize the process parameters of gate location, injection flow rate, mold temperature and melt temperature, to approach the manufactured fiber orientation distribution close to the optimized result produced by the CACD module; besides, the structural analysis CAE module generates the mechanical performance result to support the CACD module, as well as to validate the final design. By applying this framework, the final structural design including the fiber orientation distribution, will perform better in mechanical properties, and consume less matrix and fiber materials; besides, the design maturity can be approached in shorter time. To prove the effectiveness, a plastic gripper design will be comprehensively studied.     

AutoCAD三维实体图形生成二维图形的实现

计算机辅助设计(CAD)是计算机应用技术中一项重要的技术。在CAD领域中,技术人员利用专门的计算机辅助设计软件来制作表现物体几何特征。AutoCAD是新一代计算机辅助设计软件,其功能强大,使用方便的特点在多种工程设计中得到广泛的应用。AutoCAD有强大的三维功能,可以在三维空间中先建立模型并从不同角度观察和处理模型,从三维模型可以生成各个方向的视图。本文主要介绍在AutoCAD中使用相关命令完成三维实体图形生成二维图形的方法。     

T 样条用于计算机辅助设计、分析和制造的 新型表示方法

几何造型主要研究在计算机环境下几何模型的表示与设计,其是计算机辅助设计、工程和制造领 域中重要的基础研究方向。当前工业制造中几何模型表示的标准是非均匀有理 B 样条(NURBS)。然而,由于张量 积拓扑结构,NURBS 在表示复杂几何模型时具有难以克服的局限性。T 样条是一种新型兼容 NURBS 的自由曲面 造型表示技术。由于克服了 NURBS 的多个重要的局限,T 样条自提出后引起了学术界和工业界的极大关注。为 了使国内外同行对 T 样条的发展历程和研究现状有一个较为全面的了解,对其进行系统综述。在广泛文献调研的 基础上,对 T 样条的定义、基础算法,以及在计算机辅助设计、工程和制造中的应用进行归纳总结和详细分析, 重点分析了这些算法的基本思想和原理,比较了其优点和不足。由于工业界对几何表示的精度和效率的要求越来 越高,导致 T 样条的研究仍然不完善,还存在大量亟待解决的问题和可能的发展方向。     

Three-dimensional monolithic microwave integrated circuit technology for fully computer-aided design-compatible monolithic microwave integrated circuit development

This paper presents the advantages of the three-dimensional (3D) masterslice monolithic microwave integrated circuit (MMIC) technology and the application of its technology to computer-aided design (CAD) software. Its high level of freedom in transmission line routing offers design flexibility and the high integration of 3D MMICs. A 20-GHz single-chip receiver and 60 GHz amplifier are demonstrated. The 3D masterslice MMIC technology, an advanced MMIC design method, is effective in making existing CAD software fully CAD compatible by attaching software packages which allow the sharing of parameters between schema and layout, autorouting, customized simulation and database including reference circuits, and so on. Masterslice MMIC CAD software is also developed. © 1998 John Wiley & Sons, Inc. Int J RF and Microwave CAE 8: 498–506, 1998.     

Object-oriented CAD for Hydraulic Circuits of Pressing Machines

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计算机辅助概念设计研究

本文基于计算机辅助概念设计的重要性,首先介绍了产品设计的发展、相关软件CAD的开发与发展;以及产品设计的趋势,包括集成化、标准化、智能化和网络化等。接着又重点介绍计算机辅助概念设计的关键技术,主要包括产品信息建模和推理,从而说明计算机辅助概念设计具有重要的研究意义。