Introduction cad
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CAD (computer-aided design) involves using computers to aid in engineering design. It allows for 2D and 3D modeling/drafting, visualization, analysis such as finite element method simulations, and integration with CAM (computer-aided manufacturing). CAD modeling involves defining objects, their relationships, properties, and orientations. Models are visualized through display techniques like projections and surface/solid modeling by storing information about bounding curves and surfaces. Data is stored in databases linking curves, surfaces, and solids. Common input devices include mice, trackballs, tablets, and light pens while output occurs through plotters, printers, and refresh-based graphics displays.
Introduction cad
- 1. INTRODUCTION TO CAD What is CAD? –Integration of CS techniques in engineering design –Use of computers(hardware & software)for designing products –Numerical method, optimizations etc. –2D/3D drafting –3D modeling for visualization –Modeling curves,surfaces,solids,mechanism,assemblies, etc.
- 2. • ANALYSIS – Stress (deflection analysis,I.e. numerical methods,FEM – Simulation of actual use – Optimizations – Applications – CAD/CAM integration – Process planning
- 13. 3 ASPECTS OF CAD • Modeling • Display/visualization • Applications • MODELING – Definition of objects – Relation between objects – Properties – Orientations in suitable co-ordinate system – Modification of existing definition (editing)
- 14. • DISPLAY VISULIAZITION AIDS – Display of model objects – Mapping objects onto screen coordinates – Surface display,shading – Projections – Hidden line removal when multiple surfaces are displayed
- 15. REQUIREMENTS OF MODELING • Solids are modeled by storing information of constituent surfaces • This help in – Displaying surfaces(3D) – Computing solid properties – Modeling by storing info.on bounding curves or by storing their geometric definitions
- 16. DATA BASES FOR CAD Volume Plane surfaces Warped surfaces curves Net of curves patch point Is bounded by Is boundary of Consist of Belongs to Belongs to Consist of surface unit Has boundary curve Is chain of Makes up precedes succeeds Has starting point delimits surface Curve segment
- 17. LIST OF REFERENCE BOOKS • Principal of interactive CG by Newman & sprawl* • Geometric modeling by Mortenson* • Fundamental of ICG by Foley & van dam • Procedural elements of CG by Rogers* • Mathematical elements of CG by Rogers and Adams • Principal of CG by Hearn & baker • Computer graphics,A programming approach by Steven & Harrington
- 18. • An introduction to FE computations by Hinton & Owen • An introduction to FE in engineering* by Chandrupatla & Belegundu • Zincowicz (3C) • Zincowicz & taylor (4C)
- 19. Evaluations • Minors (I and II) – 30% • Major --- 40% • Labs ---- 20 % • Quizes --- 10%
- 20. DISPLAY DEVICES • Storage tube devices • Permanent phosphorescence • For erasing entire screen is flooded with a particular voltage • Can draw a line from any point to any point • CALLIGRAPHIC REFRESH GRAPHICS DISPLAY • Picture is refreshed 40-50 times a second
- 21. • Display buffer & controller • Stores INFO about each entity to be displayed Display buffer Vector/character generator CRT controller Repeats whole process 40-50 times a second
- 22. RASTER REFRESH GRAPHICS DISPLAY • SCREEN IS A MATRIX OF POINTS • Each point (pixel) can be bright/dark • Lines & curves as series of bright pixels
- 23. • Frame buffer stores a bit for each pixel(I if on, o if off)bit plane • Additional bit planes for achieving different gray levels/colors. • The programmer modifies the frame buffer • And the display controller refreshes the screen on the basis of the frame buffer
- 24. INPUT OUTPUT DEVICES • Input devices – Analog type:mouse (ball type) – X-y variable Resistance
- 25. – Track ball – Joy stick • Digital type • Light pen – Light sensitive diode to point the screen – Positioned is sensed on basis of when pen senses light
- 26. TABLET AND PEN Pen emits radio frequency and intensity received by each wire tells the position Grid of wire
- 27. HARDCOPY AND OUTPUT DEVICES • Flat bed plotters – Pen – X-drive motor & Y-drive motor – Pen raise & lower mechanism – Controller – Drum plotter • Pen • Raise and lower mechanism
- 28. • X-drive(for pen) & Y drive(for drum) motors • Controller • Printers – DMP – Laser – Inkjet