Principles of CAD

Section 1 The Design Process.- Module 1.1 The Relationship between Geometry and Function.- Specification of Needs.- Deriving Functions.- Geometric Form.- Geometry-based information.- Module 1.2 The Form of the Design Process.- Interdependency of Design.- Anatomy of Design.- Morphology of Design.- Over-constrained Design.- Under-constrained Design.- Module 1.3 Traditional Drawing Practices.- Communication of Engineering Information.- Drawing Representation by Drafting and CAD.- A Reference for Engineering Information.- Changing Role of the Drawing within CAD.- The Engineering Database.- Module 1.4 The Development of the CAD Industry.- Graphical Displays.- Interactive Drawing.- Styled Surfaces.- Design-based origins of CAD/CAM Systems.- Three-dimesional Modelling.- The Manufacturing Interface.- Current System Availability.- Exercises.- Section 2 System Configuration.- Module 2.1 Workstations.- Vector Display Screens.- Direct-view Storage Screens.- Raster Display Screens.- Special-purpose Facilities.- Cursor Key Input Devices.- Direct Cursor Control Devices.- Direct Pointing Devices.- Tablet and Menu Input Procedures.- Choice of Input Device.- Module 2.2 Computers—Mainframes to Micros.- Time-sharing Facilities.- Mini-computer Turnkey Systems.- Micro-computer Systems.- The Workstation Approach.- Further Changes in Computational Facilities.- Module 2.3 Output Devices.- Pictorial Output.- Terminal Printers and Plotters.- Pen Plotters.- Speed Limitations.- Electrostatic Plotters.- Laser Scanning and Microfilming.- Summary.- Module 2.4 Data Storage.- Management of Data.- Main Design File.- Direct Support Files.- Alternative Design Files.- Personal Files.- Design Approval.- Short-term Storage.- Archiving and Retrieval.- Control of Data.- Module 2.5 Networked Systems.- Independent Workstations.- Network File-handling.- Networks Reflecting the Design Process.- Exercises.- Section 3 Entity Descriptions.- Module 3.1 Points, Lines and Circular Arcs.- Cartesian Coordinates.- Nodes.- Entities.- Node and Entity Lists.- Module 3.2 Basic Geometric Manipulations.- Insertion.- Deletion.- Translation and Rotation.- Move and Copy.- Intersections and Trimming.- Storage and Retrieval.- Module 3.3 Free-form Curves 1.- Explicit and Implicit Functions.- Use of Parameters.- Ferguson Cubics.- Bézier Cubics.- More General Bézier Forms.- Problems of High Degree Curves.- Summary.- Module 3.4 Free-form Curves 2.- Homogeneous Coordinates.- The Bézier Rational Quadratic Form.- B-spline Segments.- B-spline Basis Functions.- An Example.- Some Properties and Local Control.- Module 3.5 Finding Intersections of Free-form Curves.- Iterative Solution of Simultaneous Equations.- Boxes.- Subdivision and the De Casteljau Algorithm.- The Intersection Algorithm.- Summary.- Module 3.6 Surfaces.- Ruled Surfaces.- Bézier and B-spline Patches.- Putting Patches Together.- User Interaction for Surface Creation.- Exercises.- Section 4 View Transformations.- Module 4.1 Two-dimensional Transformations—Pan, Rotate and Zoom.- Zoom.- Pan and Rotate.- Operations on the Node List.- Coordinates for the Display.- Clipping.- Module 4.2 Three-dimensional Transformation Matrices.- View Direction.- Homogeneous Coordinates.- Matrix Transformations.- A Single Form of Transform.- Module 4.3 Axial and Observer Systems.- Line of Sight.- Viewing Rotations.- Observer Coordinates.- Compound Transformations.- Order of Viewing and Display Transformations.- Module 4.4 The Use of Perspective.- The Depth Coordinate.- The Introduction of Perspective.- Matrix Form.- Effects of the Eye Coordinates.- Module 4.5 Multi-view Presentations.- Two-dimensional CAD.- Three-dimensional CAD — Only One Model.- Multiple Views from the Model.- User Interaction with Multiple Views.- Module 4.6 Advanced Viewing Techniques.- Intensity Cueing.- Graphics Processing in the Workstation.- Real-time Transformations.- Stereoscopic Techniques.- Genuine Three Dimensions.- Exercises.- Section 5 Types of CAD Modelling Systems.- Module 5.1 Two-dimensional Drafting Practice.- Orthographic Projection.- Orthogonal Planes.- First and Third Angle Projections.- Standards.- Use of CAD.- Module 5.2 Three-dimensional Wireframe Models.- Problems of Wireframe Representation.- Hidden Line Removal.- Module 5.3 Surface Modelling.- Use of Surface Patches.- Face Lists.- Surfaces Only Where Needed.- Advantages of Surface Modellers.- Module 5.4 Solid Modelling.- Volumetric and Other Properties.- Constructive Solid Geometry.- Boundary Representation.- Comparison of CSG, B-rep and Surface Modelling Approaches.- Speed of Response.- Module 5.5 Display of Solid Models.- Hidden Line and Surface Removal.- Surface Shading.- Need for High Quality Shaded Images.- Exercises.- Section 6 The User Interface.- Module 6.1 User Command Language.- Numeric Input.- Command-driven Programs.- Verb-noun Commands.- Additional Qualifiers.- Command Interpretation.- Module 6.2 Use of Menus.- Menus on the Tablet.- User Configuration of the Menu.- Special Symbols.- Function Boxes.- On-Screen Menus.- Pull-down Menus.- Module 6.3 Graphics Interface Languages.- Graphics Libraries.- Need for Tailoring a CAD System.- Use of Macros of Commands.- Graphics Interface Languages.- Two Examples.- Module 6.4 Use of Parametrics.- Parameters in Design Rules.- Use of the Graphics Interface Language.- Use of the Command Language.- Use of a Journal File.- Summary.- Exercises.- Section 7 System Effectiveness and Organization.- Module 7.1 Information Flow.- Stimulation of Design Activities.- Resource Balance.- Major Resources.- Customer-related Information.- Subcontract-related Information.- Factory output.- Internal Flows.- Downstream Manufacturing Information.- Module 7.2 Establishing Design Needs.- The Drafting Process.- Standards and Codes of Practice.- Social Interaction and Experience.- Assessing Individual Processes.- Establishing Design Needs.- Module 7.3 Identifying Benefits.- Drawing Productivity.- Intitial Savings.- Minimum Staffing Levels.- Downstream Justification.- Product Development Cycle.- Accurate Geometric Description.- Accurate Jigs and Fixtures.- Considering Alternative Designs.- Reduction in Delays.- Other Areas of Benefit.- Individual Justification.- Module 7.4 Training for Operation.- Use of Vendor Training.- Reasons Given for Limiting Training.- Skills Required.- CAD/CAM Awareness.- Training for Simple Interaction.- Full Operator Training.- System Management.- Systems Development.- On-going Training.- Module 7.5 Working Environment.- The Problems.- Air Conditioning and Heating.- Lighting.- Individual Work Areas.- Seating.- Benefits of Good Ergonomics.- Module 7.6 Design and Social Structure.- Need for Planning an Installation.- Processes to be Performed.- Pivotal Activities.- Interacting Factors.- Company Size.- Existing Level of Technology.- Departmental Structure.- Module 7.7 System Management.- Monitoring Use of Correct Procedures.- Using CAD at the Appropriate Time.- Priorities.- Maintaining the System.- System Manager — a Key Company Role.- Exercises.- Section 8 Applications Programs.- Module 8.1 Analysis-centred Applications Programs.- Finite Element Analysis.- Electronic Circuit Analysis.- Kinematic Modelling.- Printed Circuit Board Layout.- Module 8.2 Manufacturing-centred Applications Programs.- Computer-aided Manufacture.- Robotic Assembly.- Mould Design.- Module 8.3 Control-centred Applications Programs.- Expert Systems.- Further Reading.