CADM-Unit 1/INTRODUCTION

Introduction about CAD

1. COMPUTER AIDED DESIGN AND MANUFACTURING

2. UNIT 1 INTRODUCTION

3. SYALLABUS Product cycle Design process Sequential and concurrent engineering Computer aided design – CAD system architecture Computer graphics – co-ordinate systems- 2D and 3D transformations - homogeneous coordinates Line drawing -Clipping- viewing transformation

4. Product cycle The cycle through which a product goes from development to retirement is called product life cycle. The product cycle starts with developing the product concept, evolving the design, engineering the product, manufacturing the part, marketing and servicing. The product undergoes the following two main processes Design process Manufacturing process

5. DESIGN PROCESS Design is an activity that needs to be well organized and should take into account all influences that are likely to be responsible for the success of the product under development . The following models are considered in design purpose Shigley Pahl and Beitz Ohsuga Earle

6. Shigley design Process 09-12-2019 7

7. Pahl and Beitz design Process 09-12-2019 8

8. Ohsuga design Process 09-12-2019 9

9. Earle design Process 09-12-2019 10

10. MORPHOLOGY OF DESIGN Morphology design refers to the study of the chronological structure of design projects. It is defined by seven phases and their sub steps. Out of seven phases, the first three phases belong to the design the proposed by asimow and the remaining four phases belong to production, distribution, consumption and retirement.

11. SEQUENCIAL ENGINEERING Three major phases of conventional manufacturing process are design, process planning and manufacturing. All these phases are sequentially carried out.

12. CONCURRENT ENGINEERING It is the methodology of restructuring the product development activity in a manufacturing organization using cross functional team approach.

13. COMPARISION BETWEEN SEQUENTIAL AND CONCURRENT ENGINEERING Product development cost Number of design changes Lead time for product development Customer satisfaction Coordination between departments

14. COMPUTER AIDED DESIGN Groover and Zimmers defined “ CAD is the technology concerned with the use of computer systems to assist the creation, modification, analysis and optimization of a design ”.

15. Roles of CAD in Design Accurately generated and easily modifiable graphical representation of the product. User can nearly view the actual product on the screen, make any modification to it and present his ideas on screen without any prototype, especially during the early stages of the design process. Complex design analysis in short time. By implementing Finite Element Analysis (FEA) methods user can perform as follows Static, dynamic & natural frequency analysis Heat transfer analysis Fluid flow analysis Plastic analysis

16. Roles of CAD in Design It records and recalls information with consistency and speed Use of Product Data Management (PDM) systems can store the whole design and processing history of a certain product for future reuse and upgrade.

17. CAD PROCESS

18. APPLICATION OF CAD Mechanical engineering Civil engineering Electrical and electronics engineering Textile industry

19. ADVANTAGES OF CAD Easy editing High quality Compact storage 3D Drawing

20. CAD SYSTEM ARCHITECTURE It is an early model which was used for the basic geometry construction and modelling purpose. Four major components of CAD System Architecture are 1. Database 2. Operating system 3. Input/output devices 4. User interface

21. COMPUTER GRAPHICS (CG) Computer graphics is a technology which uses the display of the drawing or the geometric model of the component in CAD. CG may be defined as the process of creation, storage and manipulation of drawings and pictures with aid of a computer. It is an extremely effective medium for communication between users and computers. There are two types 1. P assive CG 2. Interactive CG

22. Interactive CG The following functions of the ICG Modelling Storage Manipulation Viewing

23. ADVANTAGES OF COMPUTER GRAPHICS The object drawings can be denoted by its geometric model in three dimensions. i.e. X, Y, Z coordinates. Accurate drawings can be made. Sectional drawings can be easily created. Modification of geometric model of objects is easy. It is easy storage and retrieval of drawings.

24. APPLICATIONS OF COMPUTER GRAPHICS Paint programs Design programs Presentation graphics software Animation software CAD software Desktop publishing Education and training Image processing

25. CO-ORDINATE SYSTEMS In general, there are two types of co-ordinate system 1. Cartesian – Linear distances X,Y and Z 2. Polar – Angles such as θ , α , φ

26. Left hand and right hand co-ordinate systems Multiple co-ordinate systems World co-ordinate system Object co-ordinate system Hierarchical co-ordinate system View point co-ordinate system Model view co-ordinate system Screen co-ordinate system View port co-ordinate system

27. Left and right handed coordinate system 09-12-2019 36

28. 2D & 3D (GEOMETRIC)TRANSFORMATION A geometric transformation is an operation that modifies its shape, size, position, orientation etc. with respect to its current configuration operating on the vertices. Some of the important transformations are Translation Scaling Rotation Reflection Shear 09-12-2019 37

29. 2D & 3D TRASLATION 09-12-2019 38 2D Formula 3D Formula

30. 2D & 3D SCALING 09-12-2019 39 2D Formula 3D Formula

31. 2D & 3D ROTATION 09-12-2019 40 2D Formula 3D Formula

32. HOMOGENEOUS TRANSFORMATION The three dimensional representation of two dimensional plane is called as homogeneous representation and the transformation using homogeneous representation is called homogeneous transformation. 09-12-2019 41

33. HOMOGENEOUS TRANSFORMATION 09-12-2019 42

34. LINE DRAWING 09-12-2019 43 Straight line segments are used a great deal in computer generated pictures. The following criteria have been stipulated for line drawing displays: Lines should appear straight Lines should terminate accurately Lines should have constant density Line density should be independent of length and angle Line should be drawn rapidly

35. DDA ALGORITHM 09-12-2019 44 A popular method uses an algorithm known as “ Digital Differential Analyzer ” which generates lines from their differential equations. For a line segment joining two points P1 and P2, a parametric representation is given by P(u) =P1+(P2-P1)u In terms of x(u) and y(u) x (u) = x1 + (x2-x1)u y(u ) = y1 + (y2-y1)u

36. BRESENHAM’S LINE ALGORITHM 09-12-2019 45 The basic principle of Bresenham’s line algorithms is to select the optimum raster location to represents a straight line. To achieve optimum raster scan, the algorithm always increments either x or y by one unit depending on the slope line. The increment in the other variable is determined by examining the distance between the actual line location and the nearest pixel. This distance is called decision variable or error.

37. CLIPPING 09-12-2019 46 If any part of the geometry is not inside the window, it is made invisible by the graphic software is called clipping.

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40. VIEWING TRANSFORMATIONS 09-12-2019 49 Displaying an image of a picture involves in mapping the co-ordinates of the picture into the appropriate coordinates on the device where the image is to be displayed.

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