## Computer Integrated and Manufacturing Three Marks pdf

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Name of the subject | Computer Integrated and Manufacturing |

Name of the Unit | Unit 1 – Computer Aided Design |

Scheme | N Scheme |

Syllabus | Tamilnadu Diploma Syllabus |

Study Material | Three Marks |

1. Define CAD.

Computer Aided Design (CAD) may be defined as the use of computer system to help in the creation, modification, analysis, and optimization of a design.

2. List out the steps involved in Shiley’s design process.

1) Recognition of need

2) Definition of problem

3) Synthesis

4) Analysis and optimization

5) Evaluation

6) Presentation

3. List out the various activities of CAD.

1) Geometric modelling

2) Engineering analysis

3) Design review and evaluation

4) Automated drafting

4. What are the benefits of CAD?

1) Productivity improvement in design.

2) Shorter lead time.

3) More flexibility in design.

4) Fever design errors.

5) Improved design analysis.

6) Standardization of design, drafting and documentation.

7) Easier creation and modification of design.

8) Easier visualization of drawings

5. Mention the important CAD software packages.

AutoCAD, Pro/E, IDEAS, UniGrpahics, CADian, SolidWorks, CADKey, CATIA, ArchiCAD, Autodesk Inventor, etc.

6. What is point plotting?

Point plotting is a process of converting a single pixel position into appropriate operations for the output device.

7. Mention any two algorithms used to plot lines.

1) Digital Differential Analyser (DDA) algorithm 2) Bresenham’s algorithm

8. What are the drawbacks in DDA algorithm?

1) Floating-point operations and rounding off are time consuming.

2) Due to the accumulation of round-off error, the calculated pixel positions may drift away from the true line path for long line.

9. What is transformation?

In computer graphics, the drawings can be modified by performing some mathematical operations on the coordinates of geometric elements. These operations are called transformations. Translation, scaling, and rotation are the basic transformations.

10. Define translation.

Translation involves moving the geometric elements from one location to another. In matrix notation, it can be represented as (x’, y’) = (x, y) + T

Where,

x’, y’ = Coordinates of the translated points

x, y = Coordinates of the original point m,

n = Movement in the X and Y direction respectively.

T = Translation matrix = (m, n)

11. What is scaling?

Enlarging or reducing the size of a graphic element is known as scaling. The points of an element can be scaled by the scaling matrix as follows: (x’, y’) = (x, y) S

12. What is rotation?

It involves the rotation of an object about its origin by an angle θ. The object is moved while rotating. In matrix notations, the procedure will be as follows: (x’, y’) = (x, y) R

13. Write down the rotation matrix for rotating an object about X-axis.

The rotation about X-axis by an angle θ in three-dimensional space is represented in matrix notation as follows: (x’, y’, z’) = (x, y, z) Rx

14. Define concatenation.

Concatenation is the process of combining the single transformations as a sequence of transformations. The combined transformations are called concatenated transformations. Concatenated transformations are generally performed during the editing process in a graphic model.

15. What are the techniques of geometric modelling?

1) Wireframe modelling 2) Surface modelling 3) Solid modeling

16. List out advantages of wireframe modelling.

1) It is easy to construct

2) It needs less memory space.

3) It takes less manipulation time.

4) It is best suitable for manipulations as orthographic, isometric and perspective views.

17. List out various types of surfaces.

1) Ruled surface

2) Surface of revolution

3) Tabulated cylinder

4) Bezier surface

5) B–spline surface

6) NURBS

7) Coons surfaces

8) Swept surface

9) Fillet surface

10) Offset surface

18. List out the applications of surface modelling.

1) Checking for interference between mating parts.

2) Generating cross sectional views.

3) Generating finite element meshes.

4) Generating NC tool paths for continuous path machining

19. State the applications of surface modeling.

1) Less confusing than wireframe model.

2) Hidden line and surface algorithms give realism to the model.

3) Shading algorithms are also available.

20. List out the schemes available for solid modelling.

1) Constructive solid geometry (CSG)

2) Boundary representation (B–rep)

3) Pure primitive instancing

4) Generalized sweep

5) Cellular decomposition

6) Hybrid scheme

21. List out the various solid modelling entities.

1) Block

2) Cylinder

3) Cone

4) Sphere

5) Wedge

6) Torus

22. What is the basic difference between CSG and B-rep?

In CSG, solid model is built from solid graphic primitives. In B-rep, solid model is obtained by creating the outline or boundary of the object.

23. What is hybrid scheme?

Hybrid scheme is the combination of both constructive solid geometry and boundary representation approach. It makes use of the relative benefits of both approaches overcoming their relative weaknesses.

24. List out the applications of solid modelling.

1) Creating hidden line drawings, sections, and shaded images.

2) Calculating mass properties such as total surface area, volume, centre of gravity, moments of inertia, radius of gyration, etc.

3) Kinematics analysis of solid assemblies.

4) Dynamics interference analysis.

5) Process planning for manufacture.

6) CNC tool path simulation and program verification

25. What are the advantages of solid modelling.

1) Solid model is complete and more understandable.

2) Solid models can be created easily.

3) It gives information about interior details.

4) It stores more information about geometry of the object.

5) It is best suitable for mass properties calculation.

26. What is graphic standard?

The standards used in CAD for exchanging data are called graphics standards.

27. What are the needs for graphics standard?

1) Application program portability

2) Picture data portability

3) Text portability

4) Object database portability

28. List out the common graphics standards.

1) GKS (Graphical Kernel System)

2) OpenGL (Open Graphics Library)

3) IGES (Initial Graphics Exchange Specification)

4) DXF (Drawing Exchange Format)

5) VDI (Virtual Device Interface)

6) VDM (Virtual Device Metafile)

7) WMF (Windows Meta File)

29. What is GKS? State its objectives.

Graphical Kernel System is a set of procedures that can be called by user programs for carrying out certain generalized functions.

Objectives of GKS :

1)To provide the complete range of graphical facilities.

2)To control all the graphic and display devices.

3)To be small enough for a variety of programs.

30. List out the subsection in IGES format.

1) Start section

2) Global section

3) Directory entry section

4) Parameter data section

5) Terminate section

31. What are the advantages of DXF?

1) The DXF file format is the most compatible vector file type.

2) DXF files are used to exchange data between different CAD programs.

3) It can be viewed and edited in any CAD/CAM software.

4) It is easy to process DXF files and divide it into small components.

5) The DXF file specification is freely available in public.

32. Define FEA?

Finite element analysis (FEA) is a computer simulation technique used in engineering analysis to determine the behaviour of structures and components under a variety of conditions.

33. Mention the basic steps in FEA.

1) Pre-processing

2) Analysis (Computation of solution)

3) Post processing (Visualization)

34. List out the applications of FEA.

Determination of stresses and displacements.

1.Heat transfer

2.Solid state diffusion

3.Reactions with moving boundaries

4.Fluid dynamics

5.Electromagnetism

35. What are the advantages of FEA?

1.Increased accuracy

2.Enhanced design

3.Better insight into critical design parameters

4.Virtual prototyping

5.Fewer hardware prototypes

6.Faster and less expensive design cycle

7.Increased productivity

8.Increased revenue