ME2110. Topic 3 : Problem Understanding

Transcription

1 ME2110 Topic 3 : Problem Understanding

2 PRODUCT LIFECYCLE Phases of Design Start End A. Customer/Product Requirements B. Design Specification C. Conceptual Design I. Concept Generation II. Concept Evaluation D. Detail Design E. Prototyping F. Design Finalization I. Specification for Production Manufacturing Usable Life End of Life Concurrent NOT Linear 2

3 DT 1&2: Understanding the Design Task A. Customer/Product Requirements Problem understanding, Initial Analysis DT1 P.U.F DT2 H.o.Q B. Design Specification Target Performance Metrics, Design Constraints DT4 Design Spec. Sheet C. Conceptual Design I. Concept Generation II. Concept Evaluation D. Detail Design E. Prototyping F. Design Finalization I. Specification for Production DT3 Function tree 3

4 1. Types of Design Example: CANSAT - Competition Design Task Competition result CANSAT is on-target, literally! Coke-can satellite - CANSAT 4

5 2. Customer Requirements Key Concepts: Seeding questions: Where can I sell product? What is target Market?, Why will people buy it? Why is it important? Customer side : Needs, Wants, Desires Product side : Features, Benefits, Quality Design process is most successful iff. customers quality function is embedded in the product QFD - Quality Function Deployment: Design process originated in Japan to rigorously ensure customer-centric product development Review Class Notes 5

6 Customer Requirements DT1 - Problem Understanding Form Ensures evaluation of relative importance of Customer Requirements Establishes relationships between Customer Requirements and Design Requirements using Relationship Matrix Customer WHATS into Design HOWS Analysis: Blank Row customer requirement not met; Engineer doesn t care Blank Column design requirement that customer doesn t want Be aware of intrinsic requirements Design Requirements 1 n Relationship Weight Relationship Matrix Strong 9 Medium 3 Weak 1 6

7 3. Product Functions What is a Product Function? Actions the product must be capable of DOING Abstract formulation of task What it is NOT: A specific solution path - eg. Turn Light On A Constraint eg. Be smaller than Approach: Drill down to the Hows 7

8 DT3 Example: Active-Safety Car Seat Consider the design of active-safety seats to increase occupant safety Use a Function Tree to establish/identify the product functions Conventional Car Seat Movie (see ME 2110 Homepage) Moving Car Seat Movie (see ME 2110 Homepage) 8

9 DT3 Example: Active-Safety Car Seat Close, but not quite there 9

10 DT3 Example: Active-Safety Car Seat Technically accurate, but not only solution Active Safety Car-Seat Be Comfortable Constrain occupant Provide Active Safety Conform to User Shape Maintain cushioning Sense Collision Adjust Occ. motion Increase lower-leg clearance Increase head space 10

11 DT3 Example: Pole-Vault Pole 11

12 Pole-Vault Pole Functions Shoot Athlete High Into the Air (Repeatedly) Support Load Be Easy to Use Be Consistent Bend Spring Back Lightweight Fit Comfortably in Hands Be Labeled Properly Maintain Stiffness Warn User Alert User Inform User 12

13 4. Design Specifications What is a Design Specification Numerical target (TPM) or constraint Derived from Design Standard, Design Constraint, or Design Analysis Specification Categories Geometric Material Kinematics Signals Dynamics Safety Energy Ergonomics Costs Schedules Assembly Transportation Operation Quality Control Recycling 13

14 DT4 Design Specification Sheet/List List of Design Specifications, Source, Design responsibility Tracks versioning by including date of modification or spec change Specifications arranged by category 14

15 DT4 Example Pole Vault Pole Specification For: A Pole Vault Pole Changes D/W D Requirements Shoot Idiot 3-6m into the air. Resp. Source D W W W D D D D W D D Geometry Diameter between 1-2 Length between 10'-17'6" Kinematics Damping ratio < 0.1 Forces Bending Force Scalable Bending angle > 180 deg. Materials Moldable Durable Ductile Not temperature dependent Safety Will not fracture 99% stiffness after 5k Bends Standard Design Team Standard USHSF Standard USHSF USHSF 15

16 5. Quality Function Deployment Casual-wear in Japan [Photo from Dr. Singhose] 16

17 Customer Requirements Importance Customer Comp. Assessment DT2 House of Quality Primary design tool in QFD Ensures comprehensive understanding of design task and product requirements Builds on P.U.F by adding rooms for: Design Trade-off & Analysis Identification Technical Importance identifies key design requirements for product non-subjectively Customer Competitive Assessment Technical Competitive Assessment Design Target Specification Absolute Correlation Matrix Design Requirements 1 n Relationship Matrix 1 n R Relative 1/ R n/ R TPMs Technical Competitive Assessment 17

18 H.o.Q Matrices Relationship Matrix: Relates Customer Requirements to Design requirements WHATS to HOWS Symbolic Entries with larger weighting scale Correlation Matrix: Relates Design Requirements to Design requirements Hows to HOWS Clearly identifies design trade-offs Demonstrates areas for optimization efforts Relationship Symbol Weight Strong 9 Medium 3 Weak 1 Co-Relationship Strong Positive Positive Negative Strong Negative Symbol 18

19 H.o.Q Coffee Example Product: A cup of coffee Explicit Requirements: Be Hot, Taste Good, Smell Good, Stimulating, Look like Coffee, No Grounds, Reasonable Cost Intrinsic Requirements: Non-Toxic 19

20 Technical Importance Absolute 1 : 8*9 + 3*6 + 9*9 +10*1 = 181 Relative R = 682 1/ R 181 / 682 =

21 H.o.Q Design Understanding Analysis House of Quality is a comprehensive summary of the understanding of a design task. HoQ exposes areas for detailed analysis and additional evaluation H.o.Q Analysis: Identify Blank rows and columns Compare customer vs technical competitive surveys Identify and Resolve conflicts Identify advantages (marketing points) Confirm target performance metrics Identify areas for detailed design optimization Strong negative correlations Target direction indicators 21

22 HoQ Detailed Example Product: Car door Customer requirements? 22

23 HoQ Detailed Example Product: Car door 23

24 Key Concepts Design is a Problem Solving Process Multiple Phases of Design Customer Requirements Intrinsic requirements Problem understanding Form Product Functions drill down to the how's Quality Function Deployment House of Quality 24