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Design Tools 1 William Oakes, P.E Director of EPICS

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Presentation on theme: "Design Tools 1 William Oakes, P.E Director of EPICS"— Presentation transcript:

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

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