Loading...Principles of CAD – A Coursebook
a. J. Medland, Glen Mullineux
Contents
Authors’ Preface
How to Use This Book
Section 1 the Design Process
Module 1.1 the Relationship Between Geometry
And Function 2
Specification of Needs 2
Deriving Functions 3
Geometric Form 4
Geometry-based Information 5
Module 1.2 the Form of the Design Process 7
Interdependency of Design 8
Anatomy of Design 9
Morphology of Design 10
Over-constrained Design 10
Under-constrained Design 11
Module 1.3 Traditional Drawing Practices 12
Communication of Engineering Information 12
Drawing Representation by Drafting and CAD 13
A Referencefor Engineering Information 13
Changing Role of the Drawing Within CAD 13
The Engineering Database 14
Module 1.4 the Development of the CAD
Industry 15
Graphical Displays 15
Interactive Drawing 15
Styled Surfaces 15
Design-based Origins of CAD/camsystems 16vi
Three-dimesional Modelling 17
The Manufacturing Interface 18
Current System Availability 18
Exercises 19
Section 2 System Configuration 21
Module 2.1 Workstations 23
Vector Display Screens 23
Direct-view Storage Screens 23
Raster Display Screens 24
Special-purpose Facilities 26
Cursor Key Input Devices 27
Direct Cursor Control Devices 27
Direct Pointing Devices 27
Tablet and Menu Input Procedures 28
Choice of Input Device 28
Module 2.2 Computers-mainframes to Micros 29
Time-sharing Facilities 29
Mini-computer Turnkey Systems 30
Micro-computer Systems 31
The Workstation Approach 32
Further Changes in Computational Facilities 32
Module 2.3 Output Devices 33
Pictorial Output 34
Terminal Printers and Plotters 34
Pen Plotters 35
Speed Limitations 36
Electrostatic Plotters 36
Laser Scanning and Microf Ilming 37
Summary 37
Module 2.4 Data Storage 37
Management of Data 38
Main Design File 39
Direct Support Files 39
Alternative Design Files 39
Personal Files 39
Design Approval 40
Short-term Storage 40
Archiving and Retrieval 40
Control of Data 41
Module 2.5 Networked Systems 42
Independent Workstations 42
Network File-handling 43
Networks Reflecting the Design Process 44
Exercises 45
Section 3 Entity Descriptions 47
Module 3.1 Points, Lines and Circular Arcs 48
Cartesian Coordinates 48
Nodes 50
Entities 51vii
Node and Entity Lists 53
Module 3.2 Basic Geometric Manipulations 54
Insertion 54
Deletion 54
Translation and Rotation 55
Move and Copy 56
Intersections and Trimming 56
Storage and Retrieval 58
Module 3.3 Free-form Curves 1 58
Explicit and Implicit Functions 59
Use of Parameters 59
Ferguson Cubics 59
Bezier Cubics 60
More General Bezier Forms 61
Problems of High Degree Curves 63
Summary 64
Module 3.4 Free-form Curves 2 64
Homogeneous Coordinates 65
The Bezier Rational Quadratic Form 65
B-spline Segments 67
B-spline Basis Functions 68
An Example 70
Some Properties and Local Control 70
Module 3.5 Finding Intersections of Free-form
Curves 72
Iterative Solution of Simultaneous Equations 72
Boxes 72
Subdivision and the De Castetjau Algorithm 72
The Intersection Algorithm 74
Summary 76
Module 3.6 Surfaces 76
Ruled Surfaces 76
Bezier and B-spline Patches 77
Putting Patches Together 80
User Interactionforsurface Creation 80
Exercises 83
Section 4 View Transformations 85
Module 4.1 Two-dimensional Transformationspan, Rotate and Zoom 86
Zoom 86
Pan and Rotate 86
Operations on the Node List 87
Coordinatesfor the Display 88
Clipping 89
Module 4.2 Three-dimensional Transformation
Matrices 89
View Direction 89
Homogeneous Coordinates 90
Matrix Transformations 90viii
A Single Form of Transform 92
Module 4.3 Axial and Observer Systems 92
Line of Sight 93
Viewing Rotations 93
Observer Coordinates 93
Compound Transformations 94
Order of Viewing and Display Transformations 95
Module 4.4 the Use of Perspective 96
The Depth Coordinate 96
The Introduction of Perspective 97
Matrix Form 97
Effects of the Eye Coordinates 98
Module 4.5 Multi-view Presentations 99
Two-dimensional CAD 99
Three-dimensional CAD – Only One Model 99
Multiple Viewsfrom the Model 99
User Interaction With Multiple Views 101
Module 4.6 Advanced Viewing Techniques 101
Intensity Cueing 102
Graphics Processing in the Workstation 102
Real-time Transformations 103
Stereoscopic Techniques 103
Genuine Three Dimensions 103
Exercises 104
Section 5 Types of CAD Modelling
Systems 107
Module 5.1 Two-dimensional Drafting
Practice 108
Orthographic Projection 108
Orthogonal Planes 110
First and Third Angle Projections 110
Standards 113
Use of CAD 115
Module 5.2 Three-dimensional Wffieframe
Models 116
Problems of Wireframe Representation 116
Hidden Line Removal 117
Module 5.3 Surface Modelling 118
Use of Surface Patches 118
Face Lists 119
Surfaces Only Where Needed 120
Advantages of Surface Modeuers 121
Mqdxjle 5.4 Solid Modelling 121
Volumetric and Other Properties 121
Constructive Solid Geometry 122
Boundary Representation 125
Comparison of Csg, B-rep and Surface Modelling
Approaches 125
Speed of Response 127ix
Module 5.5 Display of Solid Models 127
Hidden Line and Surface Removal 127
Surface Shading 129
Needfor High Quality Shaded Images 130
Exercises 130
Section 6 the User Interface 133
Module 6.1 User Command Language 134
Numeric Input 134
Command-driven Programs 134
Verb-noun Commands 135
Additional Qualifiers 135
Command Interpretation 136
Module 6.2 Use of Menus 136
Menus on the Tablet 137
User Configuration of the Menu 138
Special Symbols 138
Function Boxes 138
On-screen Menus 139
Pull-down Menus 140
Module 6.3 Graphics Interface Languages 141
Graphics Libraries 141
Needfor Tailoring a CAD System 142
Use of Macros of Commands 142
Graphics Interface Languages 142
Two Examples 144
Module 6.4 Use of Parametrics 145
Parameters in Design Rules 146
Use of the Graphics Interface Language 146
Use of the Command Language 146
Use of Ajournalfile 147
Summary 147
Exercises 148
Section 7 System Effectiveness and
Organization 149
Module 7.1 Information Flow 151
Stimulation of Design Activities 151
Resource Balance 152
Major Resources 152
Customer-related Information 152
Subcontract-related Information 153
Factory Output 153
Internal Flows 153
Downstream Manufacturing Information 153
Module 7.2 Establishing Design Needs 154
The Drafting Process 155
Standards and Codes of Practice 156
Social Interaction and Experience 156
Assessing Individual Processes 156x
Establishing Design Needs 157
Module 7.3 Identifying Benefits 158
Drawing Productivity 158
Intitial Savings 158
Minimum Staffing Levels 158
Downstream Justification 159
Product Development Cycle 159
Accurate Geometric Description 160
Accurate Jigs and Fixtures ·161
Considering Alternative Designs 161
Reduction in Delays 162
Other Areas of Benefit 163
Individual Justification 163
Module 7.4 Training for Operation 163
Use of Vendor Training 163
Reasons Givenfor Limiting Training 164
Skills Required 164
CADicamawareness 164
Training for Simple Interaction 165
Full Operator Training 165
. System Management 165
Systems Development 166
On-going Training 166
Module 7.5 Working Environment 167
Theproblems 167
Air Conditioning and Heating 167
Lighting 168
Individual Work Areas 168
Seating 169
Benefits of Good Ergonomics 169
Module 7.6 Design and Social Structure 169
Needfor Planning an Installation 169
Processes to Be Performed 170
Pivotal Activities 170
Interacting Factors 171
Company Size 172
Existing Level of Technology 172
Departmental Structure 172
Module 7.7 System Management 173
Monitoring Use of Correct Procedures 173
Using CAD at the Appropriate Time 173
Priorities 174
Maintaining the System 174
System Manager – a Key Company Role 175
Exercises 175
Section 8 Applications Programs 177
Module 8.1 Analysis-centred Applications
Programs 178
Finite Element Analysis 179
Electronic Circuit Analysis 182xi
Kinematic Modelling 185
Printed Circuit Board Layout 188
Module 8.2 Manufacturing-centred
Applications Programs 191
Cmnputer-aided Manufacture 192
Robotic Assembly 195
Mould Design 198
Module 8.3 Control-centred Applications
Programs 200
Expert Systems 201
Further Reading 205
Index
كلمة سر فك الضغط : books-world.net
The Unzip Password : books-world.net
تحميل
يجب عليك التسجيل في الموقع لكي تتمكن من التحميل
تسجيل | تسجيل الدخول
