ES050 – Introductory Engineering Design and Innovation Studio 1 Features Prof. Paul Kurowski Oct. 30, 2009

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

3 Feature-based Modeling Process Create base part Add features until final shape is achieved Extruded BaseExtruded Cut ES1050 part 01.SLDPRT

4 Examples Extruded BaseExtruded CutRib ES050 part 03.SLDPRT

5 Extruded Base Extruded Cut Fillet Extruded Boss

6 Tools for Creating Features Geometry is defined by sketching a 2D profile on a plane, and “extending” it into 3D These profiles can be extended to 3D by:  Extruding  Revolving  Sweeping  Lofting These operations can add material or cut it away

7 Tools for Creating Features

8 Extrusion Sweep Hole Revolution Loft Extruded cut Sample of features

9 Extruded Part Profile Extrude

10 Revolved Part

11 Swept Part

12 Lofted Part

13 Other Features Fillets, chamfers and rounds Shelling Holes Ribs

14 Example Rib Round Fillet Hole Shell

15 Alternative Modeling Approaches There are usually many ways to model an object A good approach requires few steps, and is easy to modify if necessary The modeling steps do not necessarily correspond to manufacturing steps Think the steps through before you start!

16 Modeling a Bracket ES050 part 04.SLDPRT

17 One Method Step 1Step 2Step 3 ES050 part 04.SLDPRT

18 Alternative method Step 1Step 2Step 3

19 Exercise Alternative sequence of modeling operations Extruded BaseExtruded CutRib

20 Exercise Alternative sequence of modeling operations

21 Exercise Alternative sequence of modeling operations

ES050 – Introductory Engineering Design and Innovation Studio 22 Parameters and Sketching

23 Outline Design intent and parametric modelling Constraint types “Smart sketching” Examples

24 Parametric modeling Also know as Constraint-based User constrains geometry based on Design Intent Design variations can be generated by changing a few key dimensions Geometry is automatically regenerated based on constraints

25 Example D1 D2=D1/2 D4=D3/2 D3=2*D1 The part should be twice as long as it is wide The hole should be centered in both directions The hole diameter should be 50mm D5=50

26 Sketch parameters (dimensions) constrained by equations Feature created with that sketch + Cut extrude added ES050 part 02.SLDPRT

27 Smart Sketching Most CAD systems use “smart” sketching tools Design intent is inferred, and constraints added automatically as you draw For example, two lines that are nearly perpendicular “snap” perpendicular, with a constraint SolidWorks calls this “Automatic Relations”

28 SolidWorks Automatic Relations (Geometric Constraints)

29 Before adding constraints

30 After adding geometric constraints Tangent Concentric Perpendicular

31 After adding dimensional constraints

32 Unconstrained sketchConstrained sketch

33 Constraint Types Geometric constraints Dimensional constraints

34 Boolean operations Geometric constraints Dimensional constraints boolean.SLDPRT

35 Summary Parametric modeling captures design intent Easy to modify part geometry by changing parameters

36 Select the correct answer: A.First feature must be a positive feature B.Each new feature always adds more material to model C.Parameters are changed into dimensions once model has been saved D.2D sketch is used to create 2D geometry, 3D sketch is used too create 3D geometry E.Wireframe models are used primarily to model electric circuits

37 Select the correct answer: A.Sketch can only be created on a face of a solid B.Sketch can be created on a reference plane or on a flat face of solid geometry C.3D solid geometry is created by closing-up space with surfaces D.2D sketch can’t be used to construct 3D geometry E.Once solid has been created the sketch use for its definition can be safely deleted