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Computer Aided Design (CAD)

Computer Aided Design (CAD). Prof. Paul Kurowski Oct. 28, 2009. Solid model. Surface model. Wire frame model. Drawing. Evolution of CAD Technology. Manual drafting Since 1970’s: electronic drafting board. 2D representations used to represent 3D objects multi-view drawings pictorials

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Computer Aided Design (CAD)

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  1. Computer Aided Design (CAD) Prof. Paul Kurowski Oct. 28, 2009

  2. Solid model Surface model Wire frame model Drawing Evolution of CAD Technology

  3. Manual drafting Since 1970’s: electronic drafting board

  4. 2D representations used to represent 3D objects multi-view drawings pictorials Standards and conventions developed so that 3D object could be built from drawings Drawings created manually or using 2D CAD Difficult to visualize, error-prone, time-consuming Manual Drafting

  5. Simply replaces manual drawing Provides a set of drawing tools to create 2D elements Lines, circles, arcs, etc. More accurate, easier changes to drawings Still no 3D representation of the object Example: AutoCAD 2D CAD

  6. Early 1980’s: wire frame geometry

  7. 3D Wire frame Modeling • Geometric entities are lines and curves in 3D • Volume or surfaces of object not defined • Easy to store and display • Hard to interpret - ambiguous

  8. What is this? Problems with wire frame models

  9. Late 1980’s: Surface Modeling

  10. 3D Surface Modeling • Models 2D surfaces in 3D space • All points on surface are defined • useful for machining, visualization, etc. • Surfaces have no thickness, objects have no volume or solid properties • Surfaces may be open

  11. A Surface Model created using Alias StudioTools

  12. Surface Model created using Rhino

  13. Since early 1990’s: solid geometry

  14. Solid, parametric, feature based modeling • Complete and unambiguous • Solid - models have volume, and mass properties • Feature based -geometry built up by adding and subtracting features • Parametric - geometry can be modified by changing dimensions

  15. MODERN CAE TOOLS COMPUTATIONAL FLUID DYNAMICS FINITE ELEMENT ANALYSIS CAD SOLID, PARAMETRIC, FEATURE BASED ….. MOTION ANALYSIS ….. CAD (Computer Aided Design) is at the hub of other CAE (Computer Aided Engineering) tools

  16. Parametric, Feature-based Solid Model PARAMETER SOLID GEOMETRY BASE FEATURE (“POSITIVE” SOLID) CHILD OF BASE FEATURE (“NEGATIVE” SOLID) panel 01.SLDPRT

  17. Solid, parametric, feature-based Modeling Software • High-end (more powerful) • NX (UGS) • Catia (Dassault Systémes) • Pro/Engineer (Parametric Technologies Corp.) • Mid-Range (easier to use) • Solid Edge (UGS) • Inventor (Autodesk) • SolidWorks (SolidWorks Corp.) They all work basically the same way

  18. Feature-Based Solid Modeling • Parts modeled by adding features to a base part • Features represent “operations” • holes, ribs, fillets, chamfers, slots, pockets, etc. • Material can be added or subtracted • Features can be created by extrusion, sweeping, revolving, etc.

  19. Feature-based Modeling Process • Create base part • Add features until final shape is achieved Extruded Base Extruded Cut Extruded Cut

  20. Feature History Trees • Most feature-based modelers show the features and their order in a graphical tree view • This view has different names, depending on the software

  21. Solid Edge Feature Pathfinder

  22. Pro/E Wildfire Model Tree

  23. SolidWorks Feature Manager Design Tree

  24. Modifying Parts • The part is created from the history tree • Features can be added, deleted and re-ordered • Feature parameters can be changed

  25. ES1050 part 01.SLDPRT

  26. ES1050 part 01.SLDPRT

  27. ES1050 part 01.SLDPRT

  28. Summary • Most CAD systems use solid, parametric, feature-based modeling • Parts are modeled by adding features to a base feature • Features can be easily added, deleted and modified

  29. In ES1050 we use SolidWorks CAD You can burn your installation CDs in SEB1005 Installation instructions are here: http://www.eng.uwo.ca/designcentre/CAD%20resources/default.htm

  30. DESIGN CENTRE WEB SITE

  31. DESIGN CENTRE WEB SITE - CAD RESOURCES

  32. CAD RESOURCES – SolidWorks TUTORIALS

  33. Select the INCORRECT statement about solid, parametric feature driven CAD A Geometry fully represent 3D object B Base feature is created first C Features can be deleted or modified D It is a ‘hub” for CAE applications E It is based on surface geometry

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