Computer Aided Design

2 e This book describes principles, methods and tools that are common to computer applications for design tasks. CAD is considered in this book as a discipline that provides the required know-how in computer hardware and software, in systems analysis and in engineering methodology for specifying, designing, implementing, introducing, and using computer based systems for design purposes. The first chapter gives an impression of the book as a whole, and following chapters deal with the history and the components of CAD, the process aspect of CAD, CAD architecture, graphical devices and systems, CAD engineering methods, CAD data transfer, and application examples. The flood of new developments in the field and the success of the first edition of this book have led the authors to prepare this completely revised, updated and extended second edition. Extensive new material is included on computer graphics, implementation methodology and CAD data transfer; the material on graphics standards is updated. The book is aimed primarily at engineers who design or install CAD systems. It is also intended for students who seek a broad fundamental background in CAD.

Contenu

1 Introduction.- 1.1 Purpose of this Book.- 1.2 Scope of CAD.- 1.3 Content of the Book.- 1.4 Summary.- 1.5 Comments on the Second Edition.- 1.6 Acknowledgements.- 1.7 List of Frequently Used Abbreviations.- 2 History and Basic Components of CAD.- 2.1 History.- 2.2 Modules, Functions, Components.- 2.3 Graphics Standards.- 2.3.1 Reference Model for Computer Graphics.- 2.3.2 Graphical Kernel System (GKS).- 2.3.3 Computer Graphics Interface (CGI).- 2.3.4 Computer Graphics Metafile (CGM).- 2.3.5 Graphical Kernel System for Three Dimensions (GKS-3D).- 2.3.6 Programmer's Hierarchical Interactive Graphics System (PHIGS).- 2.3.7 Programmer's Hierarchical Interactive Graphical Kernel System (PHI-GKS).- 2.3.8 Language Bindings for Graphics Standards.- 2.3.9 Future Development.- 2.4 The Graphical Dialogue System.- 2.4.1 The Language Model.- 2.4.2 Interaction Styles.- 2.4.2.1 Graphics Interaction.- 2.4.2.2 Menu Selection.- 2.4.2.3 Command Languages.- 2.4.2.4 Multi-Windowing.- 2.4.3 User Interface Design Tools.- 2.4.3.1 Graphics Systems.- 2.4.3.2 Window Management Systems.- 2.4.3.3 User Interface Toolkits.- 2.4.3.4 User Interface Management Systems (UIMS).- 2.4.4 THESEUS: An Example of a User Interface Design Tool.- 2.4.4.1 System Architecture.- 2.4.4.2 Window Management.- 2.4.4.3 Output.- 2.4.4.4 Input.- 2.5 Application Interfaces to Engineering Databases.- 2.5.1 Introduction.- 2.5.2 Data Modeling in PRODAT.- 2.5.2.1 Complex Objects.- 2.5.3 Database Schema Design.- 2.5.3.1 Principles of Using Data Model Features.- 2.5.3.2 Semantic and Logical Organization.- 2.5.3.3 Objects and Interdependencies.- 2.5.3.4 Example.- 2.5.4 Version Management.- 2.5.4.1 Version Generation in the Course of a Design Process.- 2.5.4.2 Modeling of Version Interrelations.- 2.5.4.3 Version and Configuration Management based on PRODAT.- 2.5.5 Generating and Entering Data.- 2.5.5.1 System Environment.- 2.5.5.2 Criteria for Characterizing the Generation Process.- 2.5.5.3 Commercial Applications.- 2.5.5.4 Engineering Applications.- 2.5.5.5 Example.- 2.6 Integrated Systems and Methods Bases.- 2.6.1 The Concept of Integrated Systems.- 2.6.2 Methods Bases.- 2.7 Configuring, Evaluating, and Choosing CAD Systems.- 2.7.1 The CAD Evaluation Model.- 2.7.2 Phases of CAD System Choice and Introduction.- 2.7.3 Restriction Factors Versus Advantages.- 2.7.4 Organizational Parameters.- 2.7.5 Technological Parameters.- 2.7.5.1 The Industrial Design Process.- 2.7.6 The Economics of CAD Systems.- 2.7.6.1 The Initial and Annual Costs.- 2.7.6.2 The Benefits.- 2.7.6.3 Methods for the Analysis of the Economics of CAD Systems.- 2.7.7 A Decision Support for Configuring, Evaluating, and Choosing CAD Systems.- 2.7.7.1 Implementation Approaches.- 2.7.8 Conclusion.- 2.8 Interdisciplinary Aspects of CAD.- 2.9 Summary.- 2.10 Bibliography.- 3 The Process Aspect of CAD.- 3.1 Modeling of the Design Process.- 3.1.1 A Crude Model of the Design Process.- 3.1.2 A More Refined Model of the Design Process.- 3.1.3 Design Processes and Design Environments.- 3.1.4 Differences Between Conventional Design and CAD.- 3.1.5 A Network Model'of the Design Process.- 3.2 CAD Processes.- 3.2.1 Design Process and CAD Process.- 3.2.2 Design Process Characteristics and their Influence upon the CAD Process.- 3.2.3 The Environment of CAD.- 3.2.3.1 The Organization.- 3.2.3.2 The Human Environment.- 3.2.3.3 Computer Resources.- 3.2.3.4 The Interaction Phases of the CAD Process.- 3.2.4 The State of CAD Processes.- 3.2.4.1 The Lifetime of Processes.- 3.2.4.2 The Representation of the Process State.- 3.2.4.3 The Operating State.- 3.2.5 The Problem of Resources.- 3.2.5.1 Resource Availability and Conflicts of Resource Requirements.- 3.2.5.2 The Efficiency Aspect of Resources.- 3.2.5.3 CAD Machines and CAD Tools.- 3.3 Modeling in CAD.- 3.3.1 Developing a Schema.- 3.3.1.1 Basic Considerations.- 3.3.1.2 A Sample Problem.- 3.3.1.3 Naming of Objects and Attributes.- 3.3.1.4 Alternatives for a First Schema.- 3.3.2 Influence of the Operations upon Schema Planning.- 3.3.3 Subschema Transformations.- 3.3.3.1 Subschema Transformations as Part of the Schema.- 3.3.3.2 The "n-square" Problem of Subschema Transformations.- 3.3.4 Flexibility - A Measure of Prudence - Versus Efficiency.- 3.3.5 Schema Planning and Design Process Planning.- 3.3.5.1 Subprocess Planning and Data Validity.- 3.3.5.2 The Information Packages.- 3.3.6 Resulting Data Base Management System Requirements.- 3.4 Summary.- 3.5 Bibliography.- 4 The Architecture of CAD Systems.- 4.1 The Gross Architecture.- 4.1.1 Components.- 4.1.2 Interfaces.- 4.1.2.1 Development and Installation of a CAD System.- 4.1.2.2 The Invocation of a CAD System.- 4.1.2.3 Functional Interfaces in a CAD System.- 4.1.2.4 Man-Machine Communication Channels.- 4.1.2.5 Data Transfer Interfaces of CAD Systems.- 4.1.3 CAD Tools and CAD Machines.- 4.1.3.1 Tools Used in CAD System Development.- 4.1.3.2 Tools Used in CAD Systems Extension.- 4.2 Data Models.- 4.2.1 Mapping.- 4.2.1.1 The Ideal Situation.- 4.2.1.2 Reasons for Non-Ideal Mapping.- 4.2.1.3 Mapping Around the Language.- 4.2.1.4 Mapping Between Aspects.- 4.2.2 Binding.- 4.2.3 The Block Structure Dilemma.- 4.2.4 Algorithmic Modeling.- 4.3 The Resource Aspect.- 4.3.1 Software Machine Design.- 4.3.2 Designing Against Resource Conflicts.- 4.3.2.1 The Abstract Machine.- 4.3.2.2 Process State Representation.- 4.3.2.3 The Concrete Machine.- 4.3.2.4 Resource Management Strategies.- 4.3.2.5 The Components of a Software Machine.- 4.3.3 A Sample Software Machine: The Stack Machine.- 4.3.3.1 The Task and a Simple Solution.- 4.3.3.2 Planning of the Stack Machine.- 4.3.3.3 Implementation of the Stack Machine.- 4.3.4 Distributed Systems.- 4.3.5 The Graphical Kernel System GKS as a Software Machine.- 4.3.5.1 The Process Aspect in GKS.- 4.3.5.2 The Resource Aspect in GKS.- 4.4 Summary.- 4.5 Bibliography.- 5 Implementation Methodology.- 5.1 Introduction.- 5.2 Computer Graphics Hardware.- 5.2.1 Introduction.- 5.2.2 Graphical Output Devices.- 5.2.2.1 Refreshing Vector and Raster Devices.- 5.2.2.2 The Storage Tube.- 5.2.2.3 The Plasma Panel.- 5.2.2.4 Liquid Crystal Devices.- 5.2.2.5 Graphical Storage.- 5.2.2.6 Pen Plotters.- 5.2.2.7 Raster Plotters.- 5.2.3 Graphical Input Devices.- 5.2.3.1 The Lightpen.- 5.2.3.2 Tablet, Digitizer, and Touch Panel.- 5.2.3.3 Mechanical and Optical Mouse.- 5.2.3.4 Trackball, Thumbwheels, Dials, and Positioning Keys.- 5.2.3.5 Joystick, Joyswitch, 3D Mouse, and Menus.- 5.2.3.6 Scanners.- 5.3 Graphics Workstations.- 5.3.1 The Interdependence of Hardware and Software.- 5.3.2 Graphics Workstation Architecture.- 5.3.3 Personal Computers and Graphics Workstations.- 5.4 Graphics in Networks.- 5.4.1 Introduction.- 5.4.2 CAD's Requirements on Computer Networks.- 5.4.3 Basics of CAD Nets.- 5.4.4 Decentral Computin…