ES050 – Introductory Engineering Design and Innovation Studio 1 Computer Aided Design (CAD) Part 1 Prof. Paul Kurowski

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

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

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

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, there is no 3D representation of the object Example: AutoCAD

6 Early 1980’s: wire frame geometry 3D Wire frame Modeling

7 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 Problems with wire frame models: What is this? 3D Wire frame Modeling ? ?

9 Late 1980’s: Surface Modeling 3D 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 Since early 1990’s: solid geometry 3D Solid Modeling

12 3D Solid Modeling Not parametric Not feature based Parametric Feature based This has become the industry standard

13 3D 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

14 There are many 3D solid, parametric, feature based CAD systems They all work basically the same way

15 At the Western Engineering we have selected SolidWorks Double-click this icon on your desktop

16 Click this icon and open file bracket.sldprt Opening a part First look at SolidWorks

17 You should now see this, notice two windows. Model opens in isometric view This is model view window Feature Manager window First look at SolidWorks

18 Lets’ find out how to see the model in different views Click this icon to open pop-up window with different views, try selecting them as you like. First look at SolidWorks

19 You can place the model in any position by moving the mouse. Press middle mouse button to rotate the model Press middle mouse button and Ctrl key to pan the model Press middle mouse button and Shift key to zoom in and out the model First look at SolidWorks

20 At any time you may Zoom to Fit the model First look at SolidWorks

21 Now that we know ho to open the part and how to manipulate views, let’s find out what does is mean that our CAD system is feature based. First look at SolidWorks

22 Here is the Feature Manager window. Notice three features: Base-Extrude, Cut-Extrude and Fillet1. They are listed in chronological order: Base-Extrude was created first, Fillet1 was created last. Features

23 We’ll now retrace the process of model creation. Move the cursor over the Roll-back bar until a little hand shows up, then move the hand up. Roll-back bar Model Roll-back

24 With the Roll-back bar positioned above the Fillet1, the fillet disappears from the model. Roll-back bar Model Roll-back

25 With the Roll-back bar positioned above the Cut-Extrude1, the hole and the fillet disappear from the model. Roll-back bar Model Roll-back

26 With the Roll-back bar positioned above the Base-Extrude the entire model disappears. Roll-back bar Model Roll-back

27 It is now clear that our model consists of three features created in the specific order. In our model these features can’t be reordered. In other cases some features may be re-ordered. Features

28 Now let’s find out what does is mean that our CAD system is solid.

29 Move the roll-back bar all the all the way down, place the model in isometric view and select the Section View. You’ll see that material occupies the entire volume. Section view

30 Here is another proof that SolidWorks is a solid C AD system. Select the Evaluate tab and then Mass Properties icon Evaluate tabMass properties icon Mass properties assigned: 1060 Alloy Mass Properties

31 Action from the previous slide displays Mass Properties Window listing volume, mass and mass moments of inertia of the model. Mass Properties

32 In this lesson we have: Learned a brief history of CAD Introduced SolidWorks CAD system Explained what does it mean that a SolidWorks is solid and feature based. In the next lesson we’ll find out why exactly this is a parametric system. This will require us to build a modify a CAD model Summary