Download
1 / 25
260 likes | 728 Views
Ken Youssefi. UC Berkeley, ME Dept.. 2. Concept Selection (Evaluation). Minimize the possibility of misrepresenting a solution that may be effective.Engineer is not familiar with the technology.Fully consider the different ramifications of a decision.For example, not considering the costumer's ne
E N D
1. Ken Youssefi UC Berkeley, ME Dept. 1 Concept Evaluation & Selection
2. Ken Youssefi UC Berkeley, ME Dept. 2 Concept Selection (Evaluation) Minimize the possibility of misrepresenting a solution that may be effective.
Engineer is not familiar with the technology.
Fully consider the different ramifications of a decision.
For example, not considering the costumer’s need
may lead to the product failing in the marketplace.
3. Ken Youssefi UC Berkeley, ME Dept. 3 Concept Selection Design Evaluations
Occurs at all phases of product evaluation, from concept to detailed design phases. Structured decision-making methods are needed.
Quality of Information
Low quality of information - how well each alternative design would meet criterion cannot be fully understood.
High quality of information - The alternative solutions are well understood.
4. Ken Youssefi UC Berkeley, ME Dept. 4 Estimating Technical Feasibility
5. Ken Youssefi UC Berkeley, ME Dept. 5 Estimating Technical Feasibility Perceived Dimensional Units
Size and weight are directly perceived, we
can see the difference between 1 cm and 1 m.
Derived Units
Energy is not directly perceived, we cannot visualize 1 J or 100 J. Energy is a derived unit of directly perceived units.
6. Ken Youssefi UC Berkeley, ME Dept. 6 Some Reference Values
7. Ken Youssefi UC Berkeley, ME Dept. 7 Some Reference Values
8. Ken Youssefi UC Berkeley, ME Dept. 8 Some Reference Values
9. Ken Youssefi UC Berkeley, ME Dept. 9 Some Reference Values
10. Ken Youssefi UC Berkeley, ME Dept. 10 Some Reference Values
11. Ken Youssefi UC Berkeley, ME Dept. 11 Some Reference Values
12. Ken Youssefi UC Berkeley, ME Dept. 12 Some Reference Values
13. Ken Youssefi UC Berkeley, ME Dept. 13 Some Reference Values
14. Ken Youssefi UC Berkeley, ME Dept. 14 Estimation Imagine the concept to estimate
Construct a simple model
Use the model to provide a comparison with a known quantity
Judge whether the estimated quantity compares with the known quantity
15. Ken Youssefi UC Berkeley, ME Dept. 15 Example – can crusher
16. Ken Youssefi UC Berkeley, ME Dept. 16 Concept Selection (Evaluation) Technology Readiness Assessment
If a technology is to be used as part of a product design, it must be mature enough that its use is a design issue, not a research issue.
GO/NO-GO screening
Each concept must be compared to the customer requirements in an absolute fashion. Each customer need must be transformed into a question to be addressed to each concept. The questions should be answerable as either yes or maybe (go), or no (no-go). This evaluation will weed out concepts quickly and will help generate new ideas.
17. Ken Youssefi UC Berkeley, ME Dept. 17 Concept Selection Based on the Decision-Matrix (Pugh’s method)
The method is very effective for comparing concepts that are not refined enough for direct comparison with the engineering requirements.
18. Ken Youssefi UC Berkeley, ME Dept. 18 Concept Selection – Pugh’s Method Step 1 – Select the Criteria for Comparison
The list of criteria must be developed from the customer needs and engineering specifications. All team members should contribute in making the list. The list then should be debated until consensus is reached.
19. Ken Youssefi UC Berkeley, ME Dept. 19 Concept Selection – Pugh’s Method Step 2 – Select the Concepts to be Compared
These alternatives should be those that proceed from the concept generation. It is important that all the concepts to be compared be at the same level of abstraction.
Step 3 – Generate the Score
A favorite concept should be selected as a datum. All other designs are compared to it relative to each customer needs. For each comparison, the concept being evaluated is judged to be either better than (“+” score), about the same (“s” score), or worse than the datum (“-” score).
20. Ken Youssefi UC Berkeley, ME Dept. 20 Concept Selection – Pugh’s Method Step 4 – Compute the total score
Three scores are generated, the number of plus scores, the number of minus scores and the total.
If a concept has a good overall score or a high “+” score, it is important to notice what strengths it exhibits, that is, which criteria it meets better than datum. Same for “-” score.
If most concepts get the same score on a certain criterion, examine that criterion closely. More knowledge may have to be developed in the area of the criterion. Or, it may be ambiguous, is interpreted differently by different members.
21. Ken Youssefi UC Berkeley, ME Dept. 21 Bike Splashguard Concepts
22. Ken Youssefi UC Berkeley, ME Dept. 22 Pugh’s Method – Example
23. Ken Youssefi UC Berkeley, ME Dept. 23 Pugh’s Method – Example
24. Ken Youssefi UC Berkeley, ME Dept. 24 Pugh’s Method – Example
25. Ken Youssefi UC Berkeley, ME Dept. 25 Pugh’s Method – Example
26. Ken Youssefi UC Berkeley, ME Dept. 26 Summary Estimation is a critical skill to develop and can help in quickly eliminating weak concepts
The feasibility of the concepts is based on the design team’s knowledge. It is often necessary to augment this knowledge with research and development of simple models.
In order for a technology to be used in a product, it must be ready.
A go/no-go screening based on customer needs helps to eliminate some of the concepts quickly.
The decision matrix (Pugh’s method) provides means of comparing and evaluating concepts. The method gives insight into strong and weak areas of the concepts.
