1. Introduction to Solid Modeling
Parametric Modeling
Ken Youssefi
Introduction to Engineering, E10.

2. Introduction to Engineering, E10.
Why draw 3D Models?
3D models are easier to interpret.
3D models can be used to perform engineering analysis, finite element analysis (stress, deflection, thermal…..) and motion analysis
3D models can be used directly in manufacturing, Computer Numerical Control (CNC).
Less expensive than building a physical model.
3D models can be altered easily, create more concepts
Can be used for presentations and marketing.
Ken Youssefi
Introduction to Engineering, E10.

3. Basics of Finite Element Analysis (FEA)
What is FEA ?
A complex problem is divided into a smaller and simpler problems that can be solved by using the existing knowledge of mechanics of materials and mathematical tools
Why FEA ?
Modern mechanical design involves complicated shapes, sometimes made of different materials that as a whole cannot be solved by existing mathematical tools. Engineers need the FEA to evaluate their designs
Ken Youssefi
Ken Youssefi
Mechanical Engineering Dept
Introduction to Engineering, E10. 3

4. Basics of Finite Element Analysis
The process of dividing the model into small pieces is called meshing. The behavior of each element is well-known under all possible support and load scenarios. The finite element method uses elements with different shapes. Elements share common points called nodes.
mesh
analysis results
Ken Youssefi
Ken Youssefi
Mechanical Engineering Dept
Introduction to Engineering, E10. 4

5. Introduction to Engineering, E10.
Ken Youssefi
Introduction to Engineering, E10.

6. Computer Numerical Control (CNC)
A CNC machine is an NC machine with the added feature of an on-board computer.
A solid model of the part is created. 1
Program is entered into MCU via CDs or created by onboard computer 3 2
The program path is generated by computer
Tool exchanger
Programmed instructions sent to CNC machine 5
Part is machined 6
Programmed path of cutter is displayed 4
Machine Control Unit (MCU)
CNC machine
Ken Youssefi
Introduction to Engineering, E10.

7. Introduction to Engineering, E10.
CNC Machines
Machining Centers, equipped with automatic tool changers, are capable of changing 90 or more tools. Can perform milling, drilling, tapping, boring… on many faces.
Ken Youssefi
Introduction to Engineering, E10.

8. Creating Solid Models Parametric Modeling Concept
Parametric is a term used to describe a dimension’s ability to change the shape of model geometry if the dimension value is modified.
Feature-based is a term used to describe the various components of a model. A part can consist of various types of features such as holes, grooves, fillets, and chamfers.
Parametric models are featured-based,
parametric, solid modeling design program:
SolidWorks, Pro-Engineer, Unigraphics (CSG
and parametric), Autodesk Inventor, …..
Ken Youssefi
Introduction to Engineering, E10.

9. Introduction to Engineering, E10.
Design Intent
In parametric modeling, dimensions control the model.
Design intent is how your model will react when dimension values are changed.
Ken Youssefi
Introduction to Engineering, E10.

10. Introduction to Engineering, E10.
Design Intent
The drawing shows the intent of the designer that the inclined plane (chamfer) should have a flat area measuring 2.5 inches and that it should start at a point 1.25 inches from the base of the drawing. These parameters are what the designer deemed significant for this model.
2.50
2.50
1.25
4.00
Remember that the placement of dimensions is very important because they are being used to drive the shape of the geometry. If the 2.5 in. vertical dimension increases, the 2.5 in. flat across the chamfer will be maintained, but its angle will change.
Ken Youssefi
Introduction to Engineering, E10.

11. Introduction to Engineering, E10.
Design Intent
In this drawing, what is important to the designer is the vertical location and horizontal dimension of the chamfer, rather than the flat of the chamfer.
2.125
2.50
1.25
4.00
2.50
4.00
1.75
30.0O
In the last drawing, the designer calls for a specific angle for the chamfer. In this case the angle of the chamfer should be dimensioned.
Ken Youssefi
Introduction to Engineering, E10.

12. Introduction to Engineering, E10.
Design Intent
Ken Youssefi
Introduction to Engineering, E10.

13. Introduction to Engineering, E10.
Parametric Modeling
The true power of parametric modeling shines through when design changes need to be made. The design modification is made by simply changing a dimension. 60 10
 15 30
Pattern: 8 Holes
Since the counterbore is associated with the top surface of the ring, any changes in the thickness of the ring would automatically be reflected on the counterbore depth.
Ken Youssefi
Introduction to Engineering, E10.

14. Sketching and Features
When discussing the mind-set needed for working with parametric modelers, two topics need to be expanded: Sketching and Features
Sketching
Take the word sketch literally. A sketch should be just that, a sketch.
When sketching it is not necessary to create geometry with accuracy. Lines, arcs, and additional geometry need not be created with exact dimensions in mind.
When the dimensions are added, the sketch will
change size and shape. This is the essence of
Parametric Modeling.
In short, the sketch need only be the approximate size and shape of the part being designed. When dimensions are added, they will drive the size and the shape of the geometry.
Ken Youssefi
Introduction to Engineering, E10.

15. Sketching and Features
Sketched Feature
2.75
2.5
1.0
.25
.75
Create a 2D sketch.
Create a feature from the sketch by extruding, revolving, sweeping, lofting and blending.
Revolved feature
Extruded feature
Ken Youssefi
Introduction to Engineering, E10.

16. Introduction to Engineering, E10.
Creating Solids - Sweep
A Sweep feature requires a profile and a path. The profile will follow the path to create the solid.
Sweep feature
Profile (section)
Path (guide)
Ken Youssefi
Introduction to Engineering, E10.

17. Creating Solids – Loft (different profiles)
Round profile
Square profile
Round profile
Sections (profiles) do not have to be sketched on parallel planes
All sections must be either closed or open
Ken Youssefi
Introduction to Engineering, E10.

18. Creating Features from Sketches
Loft in SolidWorks
Ken Youssefi
Introduction to Engineering, E10.

19. Introduction to Engineering, E10.
Applied Feature
Applied feature does not require a sketch.
It is applied directly to the model.
Fillets and chamfers are very common
applied features.
Chamfer
Fillet
Ken Youssefi
Introduction to Engineering, E10.

20. Introduction to Engineering, E10.
Applied Features
Shell – hollowing out a solid
Ken Youssefi
Introduction to Engineering, E10.

21. Applied Features - Patterns
Linear (rectangular) pattern
Ken Youssefi
Introduction to Engineering, E10.

22. Applied Features - Patterns
Linear (rectangular) pattern
Select # of features in dir. 1 and 2
Select direction 1 and 2
Select spacing in dir. 1 and 2
Select feature to pattern
Ken Youssefi
Introduction to Engineering, E10.

23. Applied Features - Patterns
Circular (polar) pattern
Select axis of rotation
Select # of features
Select spacing between features
Select feature to pattern
Ken Youssefi
Introduction to Engineering, E10.