Design Tools 1 William Oakes

Learning Objectives At the end of this session, you will be able to: 1.Describe a decision matrix 2.Categorize potential failures for a design 3.Perform a functional decomposition

EPICS Balance 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

Design Tool: Engineering specifications

Specifications Development What does your project partner need? oDon’t just rely on what they want, find out what they need oUnderstand the problems and issues you are addressing oWho will use product and who will benefit from it? Gather Data oTalk to Project Partner and others impacted by the project How will the problem be worked? oCriteria for design teams oHow will teams be integrated oTransition plans for multiple semesters Gather input from project partner on specifications oDevelop a specifications document and share it

Customer Requirements Types of customer requirements oFunctional performance oHuman factors oPhysical oTime (reliability) oCost oStandards oTest Method oService & maintenance

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

Engineering Specifications Answers the “how” question Quantified oShould 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

Engineering Requirements Starting with the customer requirements for a cell phone, make a list of engineering requirements

Defining Requirements Benchmarks oWhat is available oWhy did they use their approach oPatent searches avoid infringement Protect IP Are we smarter than everyone else? oOr did we miss something?

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

Design Tool: Defining the System

The EPICS Design Cycle Specification Development Detailed Design Production Service Maintenance Redesign Retirement Problem Identification Conceptual Design Disposal

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 oWhat 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

Functional Decomposition Diagram Overall Function Subfunction 1 Subfunction 2 Subfunction 3

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

Functional Decomposition Each function has a box with oAn action verb oThe object(s) on which the verb acts oPossibly a modifier giving details of the function oKnown flows of materials, energy, control or information Consider WHAT not HOW

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

Generating Ideas - Brainstorming 1.Pick A Facilitator 2.Define The Problem 3.Small Group 4.Explain the Process 5.Record Ideas in a Visible Way 6.Everyone’s Involved 7.No Evaluating 8.Eliminate Duplicates 9.Pick Three

In the same group Brainstorm ways to implement one of the functions on your diagram and select the best alternative Prepare it to share

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

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

Decision Matrix Example: Getting a Job CriteriaWtsCo. ACo. BCo. CCo. D Location5 Salary4 Bonus2 Job3 Training2 Boss2 Totals

DFMEA : Design for Robustness

Design Phase: Testing for Failures Planning to avoid failures Disposal Specification Development Detailed Design Production Service Maintenance Redesign Retirement Problem Identification Conceptual Design

DFMEA Steps 1.Review the design 2.Brainstorm potential failure modes 3.List potential effects of failure 4.Rank failures a)Severity b)Occurrence c)Detection 5.Develop action plan 6.Implement fixes 7.Revisit potential failure risks

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

Brainstorm Failures What could go wrong? What could break? Are there systems your design relies upon? oe.g. myEPICS authenticates through Purdue’s career accounts Are there things that could fail over time?

Brainstorm a list of potential failures for the project

Rate failures Rating Severity How severe are the consequences to the failure Occurrence How often are the failures likely to occur? Detection How easily are the failures detected?

DFMEA Matrix Failure modeSeverityOccurrenceDetectionRating

Identify the failure scenario that should be addressed first

Develop an action plan to address the failure scenario

Continue the process Implement the plan to eliminate the failure scenario Revisit other potential failure risks oPrioritize oEliminate failure scenarios Continue until risks are below determined thresholds oShow to the design reviews for confirmation

Questions/Discussion