ES050 – Introductory Engineering Design and Innovation Studio 1 Computer Aided Design (CAD) Prof. Paul Kurowski Oct. 28, 2009

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

3 Manual drafting Since 1970’s: electronic drafting board

4 Manual Drafting 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

5 2D CAD 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

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

16 PARAMETER BASE FEATURE (“POSITIVE” SOLID) CHILD OF BASE FEATURE (“NEGATIVE” SOLID) SOLID GEOMETRY Parametric, Feature-based Solid Model 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 BaseExtruded 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:

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 AGeometry fully represent 3D object BBase feature is created first CFeatures can be deleted or modified DIt is a ‘hub” for CAE applications EIt is based on surface geometry

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