Concept Evaluation and Selection… Integrated Product and Process Design ME En 475/476

Objectives For Today Help you know what to expect for your design review this week Learn Concept Selection principles and two methods of concept selection Concept Screening Concept Scoring 2

Design Reviews This Week 3 Purpose: To give you a chance to show results Forum for feedback from instructors /others on work of team and how we perceive team is doing First of two reviews in Fall Semester 16 minutes total, not graded… Approx. Eight minute presentation – Share current status of project, decisions made, justification, and plans Approx. Last 8 minutes - questions and feedback, assessing progress in relation to the evaluation criteria on pages of the Guidebook 3 teams are scheduled at once so you can learn from other teams…

Feedback: How many teams are working on concept generation? How many teams are finished with Concept Generation? How many teams are already doing some concept selection? 4

Concept Development Process Perform Economic Analysis Benchmark Competitive Products Build and Test Models and Prototypes Identify Customer Needs Establish Target Specifications Generate Product Concepts Select Product Concept(s) Set Final Specifications Plan Downstream Development Mission Statement Test Product Concept(s) Development Plan The purpose of concept generation is to produce lots of ideas. The purpose of concept selection is to narrow the list down to one or two for further development. Integrated Product and Process Design 61 Documentation

Selecting a Concept… How do we know a proposed concept will meet our needs? 6

Concept Selection Example: Mini-Baja Rear Suspension… Trailing Arm Suspension Double Wishbone Suspension 7

Many Methods for Concept Selection External Decision Product Champion Intuition/inspiration Multi-voting Pros and Cons Prototype and test Decision Matrices Screening Scoring Other All of these methods have their advantages and disadvantages -- but decision matrices are robust and recommended 8

Concept Development Funnel 9

Four Principles of Concept Selection: 10 Which Concept should I go with and why?

Principle 1 The choice of which concept to pursue is one of the most important design decisions we make… 11

Principle 2 Concept selection often involves many competing objectives and should therefore be carried out after prioritizing the goals of all the stakeholders. 12

Principle 3 Good Screening can be evidence that a good decision process has been used… 13

Principle 4 Prototyping can be a tremendous help! 14

Decision Matrices  Step 1: Prepare a Selection Matrix  Step 2: Rate the Concepts against each criteria  Step 3: Rank the Concepts  Step 4: Combine and Improve the Concepts  Step 5: Select One or More Concepts  Step 6: Reflect on the Results and the Process 15

Step 1: Prepare Matrix CriteriaC1C2C3C4 Ease of Manuf. Appeal Ease of Use Total Score What basis should we use to choose the criteria? 16

Concept Development Process Perform Economic Analysis Benchmark Competitive Products Build and Test Models and Prototypes Identify Customer Needs Establish Target Specifications Generate Product Concepts Select Product Concept(s) Set Final Specifications Plan Downstream Development Mission Statement Test Product Concept(s) Development Plan Integrated Product and Process Design Documentation As we move forward in the design process, we always want to keep in mind Customer Needs and Specifications…

How many concepts in matrix? Too few means you leave out good concepts Too many means you spend lots of time on bad concepts Rule of thumb: no more than 12 concepts Get there by multivoting, or by keeping any concept that somebody thinks is promising Don’t try to rate all 50 concepts!

Step 2: Rate the Concepts CriteriaC1C2C3C4 Ease of Manuf Appeal0-0- Ease of Use 0+-- Total Score 19 Zip Pouch Screw Cap Clam Shell Slider

Step 3: Rank the Concepts CriteriaC1C2C3C4 Ease of Manuf Appeal0-+- Ease of Use 0+-- Total Score01 Remember, this is your “benchmark” This may be your choice 20

Example: Screening Matrix Integrated Product and Process Design 27 Page 130 Ulrich and Eppinger

Potential Weaknesses of Screening Process Not all criteria are of equal value Further look with scoring if necessary Some criteria may be missing Identify missing needs statements May be “too formulaic” Be thoughtful in your rating and ranking 22

Concept Scoring Same steps as screening, but … Matrix includes weight for each need Rating is from 1 to 5, with different concepts as the reference for each need Ranking is a weighted sum Requires more information about concepts, so needs a smaller number of concepts

Select One (or More) Concepts Don't just blindly select the concept that comes out on top… Do a sensitivity analysis…(What if?) Pay attention to risk… Consider bringing two concepts out of selection… High risk, high reward Low risk, less reward Need to make choice as soon as possible (probably through prototyping) Working on two concepts requires twice as many resources 24

Reflect on the Results and the Process Do the selected concepts make sense? Could you get a better concept by combining some of the higher-rated concepts? Can you explain the choice of the selected concepts without referring to the matrix? Do you believe in the concept you have chosen? Would rough prototyping a concept/s help you in the decision making process? 25

Team Assignment, 6 minutes: Discuss what approach you might take to screen concepts. It might be for sub concepts or entire concepts… 1. How would you establish criteria for screening? 2. Can you make a list of possible concepts? 3. Can you select a benchmark? 4. What information is needed to decide if a concept is better or worse than your benchmark? 5. Sum results. Reflect on the results 6. Choose a spokesman to share… 26

Be open to other’s opinions Show me the 2 nd and 3 rd place concepts 27

Remember… The goal of concept selection is not just to Select the best concept… The goal of concept selection is also to Develop the best concept… So, remember to combine and refine your concepts to develop better ones! 28

Summary Four principles: 1.The choice of which concept to pursue is one of the most important design decisions we make… 2. Concept selection involves many competing objectives— carry out after prioritizing goals of all stakeholders… 3. Good Screening can be evidence that a good decision process has been used… 4. Prototyping can be a great help! Concept selection methods are a way to apply judgment, not a replacement for judgment 29

Which Concept Would You Choose? 30

Thank you!

Summary… 32 Many different methods to select concepts

Failure Mode & Effects Analysis (FMEA) Severity of failure is greater, on average, for the Trailing Arm Suspension Probability of failure is greater, on average, for the Double A Arm Suspension Another Method of Concept Selection… 33

Wrap Up:  Feasibility Judgment (from hundreds down to ~20)  Concept Screening (screening or elimination method) Advantages: 1. Fast 2. Less information required 3. From ~20 to a few  Rough Prototyping (helps to get from a few to 1) 34