1. Design Tools 1 William Oakes, P.E Director of EPICS
Assoc. Prof. Engineering Education

2. Learning Objectives At the end of this session, you will be able to:
Describe a specification
Describe a decision matrix
Categorize potential failures for a design
Perform a functional decomposition
Create a personna

3. EPICS Balance Service Learning
Service-learning is a balance of the learning of design and the service we contribute the communities through completed designs and support
Service
To our partners, meeting needs in the community
Learning
Becoming good designers, professionals & active citizens
Complimentary goals that enhance each other

4. Design Tool: Engineering specifications

5. Specifications Development
What does your project partner need?
Don’t just rely on what they want, find out what they need
Understand the problems and issues you are addressing
Who will use product and who will benefit from it?
Gather Data
Talk to Project Partner and others impacted by the project
How will the problem be worked?
Criteria for design teams
How will teams be integrated
Transition plans for multiple semesters
Gather input from project partner on specifications
Develop a specifications document and share it

6. Customer Requirements
Types of customer requirements
Functional performance
Human factors
Physical
Time (reliability)
Cost
Standards
Test Method
Service & maintenance

7. Customer Requirements
For a cell phone, make a list of Ten customer requirements

8. Design Specifications
Answers the “how” question
Quantified
Should be able to measure whether you meet it
Objective quantities
A set of units should be associated with each specification
Forms the basis for your specifications document

9. Design Requirements
Starting with the customer requirements for a cell phone, make a list of design requirements

10. Defining Requirements
Benchmarks
What is available
Why did they use their approach
Patent searches
avoid infringement
Protect IP
Are we smarter than everyone else?
Or did we miss something?

11. Design Targets Set standards to meet with your design How good is good
Can be a living document
Don’t compromise on goals, but refine as the design progresses
Tool make design trade offs
Design decisions
Communication with project partner

12. Decision Matrix Table with alternatives
Quantify categories and score alternatives
Importance in different categories
Use judgement to do reality checks
Leaves documentation of thought process of design
Can be shared in design reviews

13. Criteria for Comparison
Decision Matrix
Ideas to be compared
Criteria for Comparison
Weights
Scores
Totals

14. Decision Matrix Example: Getting a Job
Criteria
Wts
Co. A
Co. B
Co. C
Co. D
Location 5
5x5=25
5x1=5
5x3=15
5x4=20
Salary 4
Bonus 2
Job 3
Training
Boss
Totals

15. Design Tool: Defining the System

16. Functional Decomposition
Breaking tasks or functions of the system down to the finest level
Create a tree diagram starting at the most general function of your system
What is the purpose of your system?
Break this function down into simpler subtasks or subfunctions
Continue until you are at the most basic functions or tasks

17. Functional Decomposition Diagram
Overall Function
Subfunction 1
Subfunction 2
Subfunction 3

18. Sample Diagram – Bike Fender
Protect rider from water and dirt off wheel
Shield rider
Steer water away from rider
Attach Splashguard

19. Functional Decomposition
Each function has a box with
An action verb
The object(s) on which the verb acts
Possibly a modifier giving details of the function
Known flows of materials, energy, control or information
Consider WHAT not HOW

20. Create a functional decomposition diagram for a mechanical pencil
Prepare them to share

21. DFMEA : Design for Robustness

22. DFMEA Steps Review the design Brainstorm potential failure modes
List potential effects of failure
Rank failures
Severity
Occurrence
Detection
RPN = Severity X Occurrence X Detection
Develop action plan
Implement fixes
Revisit potential failure risks

23. Describe the project so the whole group understands it
In a group, Identify one project to use as an example for this exercise
Describe the project so the whole group understands it

24. Brainstorm Failures What could go wrong? What could break?
Are there systems your design relies upon?
e.g. myEPICS software authenticates through Purdue’s career accounts. What if the server goes down?
Are there things that could fail over time?

25. Brainstorm a list of potential failures for the project

26. Rate failures Severity Occurrence Detection Rating (1 to 10)
How severe are the consequences to the failure
Occurrence
How often are the failures likely to occur?
Detection
How easily are the failures detected?

27. DFMEA Calculations Scores for Severity, Occurrence and Detection
1 to 10
1 = Low
10 = High
Risk Priority Number (RPN)
RPN =Severity X Occurrence X Detection

28. DFMEA Matrix Failure mode Effect of Failure Severity Occurrence
Detection
RPN Rating

29. Example
accessed 22 Aug. 2011

30. Example Chart

31. Identify the failure scenario that should be addressed first

32. Develop an action plan to address the failure scenario

33. Continue the process
Implement the plan to eliminate the failure scenario
Revisit other potential failure risks
Prioritize
Eliminate failure scenarios
Continue until risks are below determined thresholds
Show to the design reviews for confirmation

34. Questions/Discussion