1. Chapter 2 The Design Process
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

2. Design-Led Approach
We aim to develop a methodology for selecting materials and processes that is design led; that is, it uses, as inputs, the functional requirements of the design
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

3. The starting point of a design is a market need or a new idea that can be expressed as a set of design requirements – the end point is the full specification of a product that fills the need
Figure 2.1
Design Flow Chart
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

4. Material and process selection is at the component level
Figure 2.2
The product itself is called a technical system which consists of subassemblies and components
Material and process selection is at the component level
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

5. Function Structure
Figure 2.3
Systems approach to the analysis of a technical system – considers the inputs, flows, and outputs of information, energy, and materials
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

6. Convoluted Path of Design
Figure 2.4
C’s: Concepts
E’s: Embodiments of C’s
D’s: Detailed realizations of E’s
The design process is complete when a compatible path from need to specification can be identified
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

7. Design Flow Chart Figure 2.5
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

8. Figure 2.6
The central problem of materials selection in mechanical design: the interaction between function, material, process, and shape
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

9. Case Study: Device to Open Corked Bottles
Left
The market need; a device to allow access to wine contained in a corked bottle
Right
Five possible concepts, illustrating physical principles, to fill the need
Figure 2.7
Figure 2.7
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

10. Working principles for implementing three concept designs
Figure 2.8
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

11. Device to Open Corked Bottles
The embodiments identify the functional requirements of each component of the device, which might be expressed in statements such as
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

12. Detailed design of the lever of embodiment with material choice
Embodiments
Direct pull
b) Lever-assisted pull
Gear-assisted pull
Spring-assisted pull
Detailed design of the lever of embodiment with material choice
Figure 2.9
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby

13. The function structure and working principles of cork removers
Figure 2.10
The function structure and working principles of cork removers
Materials Selection in Mechanical Design, 4th Edition © 2010 Michael Ashby