1. Mechanical Design Lab. with Advanced Materials 1 What is design? 이대길 KAIST 기계공학과 교수 한국과학기술한림원 정회원 한국복합재료학회 부회장

2. Mechanical Design Lab. with Advanced Materials 2 1. Normal design processes 2. Motorola’s 6  Program 3. Axiomatic design process Contents:

3. Mechanical Design Lab. with Advanced Materials 3 1. Normal design processes Ref. J. E. Shigley, C. R. Mischke and R. G. Budynas, Mechanical Engineering Design, 7th Edition, McGraw Hill, 2003

4. Mechanical Design Lab. with Advanced Materials 4 What is engineering? Engineering= Design + Manufacturing

5. Mechanical Design Lab. with Advanced Materials 5 Design is an interplay between what we want to achieve and how we want to achieve it. What is design?

6. Mechanical Design Lab. with Advanced Materials 6 The designers (mechanical engineer, electrical engineer, mayor, CEO, etc) must do the following. 1. Know or understand their customers’ needs. 2. Define the problem they must solve to satisfy the needs. 3. Conceptualize the solution through synthesis. 4. Perform analysis to optimize the proposed solution (Adequacy assessment ). 5. Check the resulting design solution to see if it meets the original customer needs. What is design?

7. Mechanical Design Lab. with Advanced Materials 7 What is design?

8. Mechanical Design Lab. with Advanced Materials 8  Design product should be 1.Functional: satisfy the intended need and customer expectation. 2. Safe: not hazardous to the user, bystanders, or surrounding property with appropriate directions or warnings provided. 3. Reliable: perform its intended function satisfactorily or without failure at a given age. 4. Competitive: product survival. Adequacy of Design

9. Mechanical Design Lab. with Advanced Materials 9 Adequacy of Design-continued Design product should be 5. Usable: user friendly product. 6. Manufacturable: suited to mass production with a minimum number of parts (or information). 7. Marketable: purchasable with repair available.

10. Mechanical Design Lab. with Advanced Materials 10 1. Functionality 2. Strength/stress 3. Distortion/deflection/stiffness. 4. Wear 5. Corrosion 6. Safety 7. Reliability 8. Manufacturability 9. Utility (electricity, gas. etc) 10. Cost 11. Friction 12. Weight 13. Life14. Noise 15. Styling 16. Shape 17. Size 18. Control 19. Thermal Properties 20. Surface 21. Lubrication 22. Marketability 23. Maintenance 24. Volume 25. Liability 26. Remanufacturing/resource recovery Interaction between Design Process Elements

11. Mechanical Design Lab. with Advanced Materials 11  Computational Tools  CAD (Computer-aided design) software: Aries, AutoCAD, CadKey, I-deas/Unigraphics, ProEngineer, etc.  CAE (Computer-aided engineering): Finite element analysis/method (FEA or FEM): Algor, ANSYS, MSC/NASTRAN, ABAQUS, etc. Computational fluid dynamics: CFD++, FIDAP, Fluent, etc. Dynamic force and motion in mechanics: ADAMS, DADS, Working Model, etc.  Acquiring Technical Information Libraries, Government sources, Professional societies, commercial vendors, internet and TRIZ. Design Tools and Resources

12. Mechanical Design Lab. with Advanced Materials 12 Design Engineer’s Professional Responsibilities Satisfy the needs of customers (management, clients, consumers, etc.). Communicate your ideas clearly and concisely, or your technical proficiency may be compromised. The design engineer’s professional obligations include conducting activities in an ethical manner. (There’s no engineers in the hell). Engineer’s Creed from the National Society of Professional Engineers (NSPE).

13. Mechanical Design Lab. with Advanced Materials 13  Standard: a set of specifications for parts, materials, or processes intended to achieve uniformity, efficiency, and a specified quality.  Code: a set of specifications for the analysis, design, manufacture, and construction of something. All of the organizations and societies have established specifications for standards and safety or design codes. AA, AGMA, AISC, AISI, ANSI, ASM, ASME, ASTM, AWS, ABMA, BSI, IFI, I. Mech. E., BIPM, ISO, NIST, SAE, JIS, DIN Codes andStandards Codes and  Standards

14. Mechanical Design Lab. with Advanced Materials 14 Economics Standard sizes Large tolerances Breakeven points Cost estimates (cost per weight, number of parts, area, volume, horsepower, torque, capacity, speed and various performance ratios).

15. Mechanical Design Lab. with Advanced Materials 15 Safety and Product Liability The strict liability concept of product liability generally prevails in the United States. The manufacturer of an article is liable for any damage or harm that results because of a defect. It does not matter whether the manufacturer knew about the defect, or even could have known about it.

16. Mechanical Design Lab. with Advanced Materials 16 The reliability method of design is one in which we obtain the distributions of stresses and the distribution of strengths and then relate these two in order to achieve an acceptable success rate. Reliability

17. Mechanical Design Lab. with Advanced Materials 17 Should an automotive engineer increase the cost per car by 10,000 Won in order to avoid 100 failures in a production run of a million cars, where the failure would not involve safety, but would entail a 100,000 Won repair? Reliability

18. Mechanical Design Lab. with Advanced Materials 18 Should 10 billion Won be spent to save 10 million Won plus some customer inconvenience? 6  =1/10 9 Reliability

19. Mechanical Design Lab. with Advanced Materials 19 2. Motorola’s 6  Program

20. Mechanical Design Lab. with Advanced Materials 20 2. Motorola’s 6  Program  The 6  quality is a phrase made famous by Motorola once it decided to refocus on quality in the late 1970s and early 1980s.  It is a quality assurance program that has the goal of reducing the defective parts in a bath to as low as 3.4 parts per million (10 6 ).  A rigorous interpretation of 6  is really 2 defects per billion parts (10 9 ) made.  If we consider each side of center, then 6.8 components per million will lie in the tails with 3.4 on each side.

21. Mechanical Design Lab. with Advanced Materials 21 Motorola’s 6 s Program

22. Mechanical Design Lab. with Advanced Materials 22 Motorola’s 6  Program  When the center of the normal distribution curve drifts by 1.5  to the right, and is viewed still window, there will be virtually no defects in the left-side tail but a rather large number in the right-side tail (1350 parts per million).  If we view with the window of, the right tail contains 3.4 parts per million, with negligible number of parts in the left signal.  There is an infinite combination of “m  offset plus n  viewing window” for quality performance of 3.4 parts per million.  The number of 3.4 parts per million is used as the bench mark rather than the rigorous definition of 6 .

23. Mechanical Design Lab. with Advanced Materials 23 Calculations and Significant Figures Usually three or four significant figures are necessary for engineering accuracy. Make all calculations to the greatest accuracy possible and reports the results within the accuracy of the given input.

24. Mechanical Design Lab. with Advanced Materials 24 Calculations and Significant Figures To display 706 to four significant figures: 706.0, 7.060 ⅹ 10 2, 0.7060 ⅹ 10 3 To display 91600 to four significant figures: 91.60 ⅹ 10 3 When d=0.40 in  d=3.1(0.40)=1.24in=1.2 in  d=3.141592(0.40)=1.256in=1.3 in

25. Mechanical Design Lab. with Advanced Materials 25 3. Axiomatic design process

26. Mechanical Design Lab. with Advanced Materials 26 References: 1.Dai Gil Lee and Nam P. Suh, Axiomatic Design and Fabrication of Composite Structures, Oxford University Press, August, 2005. 2. Nam P. Suh, Axiomatic Design, Oxford University Press, 2000. 3. Nam P. Suh, The Principles of Design, Oxford University Press, 1990. Introduction to Axiomatic Design

27. Mechanical Design Lab. with Advanced Materials 27 ▪ There are several key concepts that are fundamental to axiomatic design. ▪ They are the existence of domains, mapping, axioms, and decomposition by zigzagging between the domains, theorems, and corollaries. Introduction to Axiomatic Design

28. Mechanical Design Lab. with Advanced Materials 28 Introduction to Axiomatic Design

29. Mechanical Design Lab. with Advanced Materials 29 ▪ The customer domain is characterized by the needs (or attributes) that the customer is looking for in a product or process or system or material. ▪ In the functional domain, the customer needs are specified in terms of functional requirements (FRs) and constraints (Cs). ▪ In order to satisfy the specified FRs, we conceive design parameters (DPs) in the physical domain. ▪ Finally, to produce the product specified in terms of DPs, we develop a process that is characterized by process variables (PVs) in the process domain. Key Concepts of Axiomatic Design Theory

30. Mechanical Design Lab. with Advanced Materials 30  Once we identify and define the perceived customer needs, these needs must be translated to FRs.  This must be done within a "solution-neutral environment." without ever thinking about existing products or what has been already designed or what the design solution should be (Japanese method).  Often designers and engineers identify solutions first by looking at existing materials or products before they define FRs, which leads to a description of what exists rather what is needed. Key Concepts of Axiomatic Design Theory

31. Mechanical Design Lab. with Advanced Materials 31 Axiom 1: The Independence Axiom Maintain the independence of the functional requirements (FRs). Axiom 2: The Information Axiom Minimize the information content of the design. TWO AXIOMS

32. Mechanical Design Lab. with Advanced Materials 32 Independence Axiom: FRs are defined as the minimum set of independent requirements that characterize the design goals. ▪ Information Axiom: The design that has the smallest information content is the best design. 1.3 Key Concepts of Axiomatic Design Theory

33. Mechanical Design Lab. with Advanced Materials 33 Knob Design for a Shaft FR 1 =Grasp the end of the shaft tightly with axial force of 30 N FR 2 =Turn the shaft by applying 15 N-m of torque DP 1 =Interference fit between the shaft and the inside diameter of the knob DP 2 =The flat surface

34. Mechanical Design Lab. with Advanced Materials 34 Knob Design for a Shaft FR 1 =Grasp the end of the shaft tightly with axial force of 30 N FR 2 =Turn the shaft by applying 15 N-m of torque DP 1 =Interference fit between the shaft and the inside diameter of the knob DP 2 =The flat surface

35. Mechanical Design Lab. with Advanced Materials 35 Bias Probability density System pdf Area within common range (A cr ) Variation from the peak value Target Design range

36. Mechanical Design Lab. with Advanced Materials 36  Information content I i for a given FR i is defined in terms of the probability P i of satisfying FR i. (1.6) 1.3 Key Concepts of Axiomatic Design Theory  The probability is determined by the overlap between the design range and the system range.

37. Mechanical Design Lab. with Advanced Materials 37 ▪ The design that has the highest probability of success is the best design. ▪ In an ideal design, the information content should be zero to satisfy the FR every time and all the time. ▪ The design goals are often subject to constraints (Cs). Constraints provide bounds on the acceptable design solutions and differ from the FRs in that they do not have to be independent. Key Concepts of Axiomatic Design Theory

38. Mechanical Design Lab. with Advanced Materials 38  FRs and DPs (as well as PVs) must be decomposed to the leaf-level until we create a hierarchy.  From an FR in the functional domain, we go to the physical domain to conceptualize a design and determine its corresponding DP.  Then, we come back to the functional domain to create FR 1 and FR 2 at the next level that collectively satisfies the highest-level FR.  Key Concepts of Axiomatic Design Theory

39. Mechanical Design Lab. with Advanced Materials 39  FR 1 and FR 2 are the FRs for the highest level DP.  Then we go to the physical domain to find DP 1 and DP 2 by conceptualizing a design at this level, which satisfies FR 1 and FR 2, respectively. 1.3 Key Concepts of Axiomatic Design Theory FR FR 1 FR 11 FR 121 FR 12 FR 122 FR 123 FR 1231 FR 1232 FR 2 Functional domain DP DP 1 DP 11 DP 121 DP 12 DP 122 DP 123 DP 1231 DP 1232 DP 2 Physical domain

40. Mechanical Design Lab. with Advanced Materials 40 FR FR 1 FR 11 FR 121 FR 12 FR 122 FR 123 FR 1231 FR 1232 FR 2 Functional domain DP DP 1 DP 11 DP 121 DP 12 DP 122 DP 123 DP 1231 DP 1232 DP 2 Physical domain 1.3 Key Concepts of Axiomatic Design Theory  This process of decomposition is continued until the FR can be satisfied without further decomposition when all of the branches reach the final state.  The final state is indicated by thick boxes, which is called a “leaf” or “leaves”.

41. Mechanical Design Lab. with Advanced Materials 41 DPs: DP 1 = Vertically hung door DP 2 = Thermal insulation material FRs: FR 1 = provide access to the food in the refrigerator. FR 2 = minimize energy consumption 1.3 Key Concepts of Axiomatic Design Theory

42. Mechanical Design Lab. with Advanced Materials 42  Bend a titanium tube to prescribed curvatures maintaining the circular cross section of the bent tube.  Titanium has a hexagonal close packed (hcp) structure so that its mechanical properties anisotropic, and it cannot be bent repeatedly because it will fracture. Design Example FR 1 = Bend a titanium tube to prescribed curvatures. FR 2 = Maintain the circular cross section of the bent tube.

43. Mechanical Design Lab. with Advanced Materials 43 Fixed set of counter-rotating grooved feed rollers Flexible set of counter- rotating grooved rollers for bending Pivot axis  1 =  2  1 >  2 11 22 11 22 Tube between the two bending rollers DP 1 = Differential rotation of the bending rollers to bend the tube DP 2 = The profile of the grooves on the periphery of the bending rollers

44. Mechanical Design Lab. with Advanced Materials 44 Design range pdf Target System pdf 90 110 100 c m FR (Length, cm) To cut Rod A to 1  10 -6 m and Rod B to 1  0.1m. Which has a higher probability of success? Cutting a Rod

45. Mechanical Design Lab. with Advanced Materials 45 FR 1 = Commuting time must be in the range of 15 to 30 minutes. FR 2 = The quality of the high school must be good, i.e., more than 65 % of the high school graduates must go to reputable colleges. FR 3 = The quality of air must be good over 340 days a year. FR 4 = The price of the house must be reasonable, i.e., a four bedroom house with 3000 square feet of heated space must be less than $ 650,000. Buying a house

46. Mechanical Design Lab. with Advanced Materials 46 FR 1 = Commuting time must be in the range of 15 to 30 minutes. FR 2 = The quality of the high school must be good, i.e., more than 65 % of the high school graduates must go to reputable colleges. FR 3 = The quality of air must be good over 340 days a year. FR 4 = The price of the house must be reasonable, i.e., a four bedroom house with 3000 square feet of heated space must be less than $ 650,000. FR 1 = Commute FR 2 = QualityFR 3 = QualityFR 4 = Price TownTime [min]of schools [%]of air [days][1000 $] A20 to 4050 to 70300 to 320450 to 550 B20 to 3050 to 75340 to 350450 to 650 C20 to 4550 to 80350 and up600 to 800 TownI 1 (bits)I 2 (bits)I 3 (bits)I 4 (bits)  I (bits) A1.02.0Infinite0 B01.3200 C2.01.002.05.0 Buying a house

47. Mechanical Design Lab. with Advanced Materials 47 K=stiffness 1  FR FR  DP DP Estimating the height of Washington Monument Students were asked to estimate the height of the George Washington Monument. They were given tape measures that can measure the length of the shadow of the monument accurately. Then they were asked to eyeball the angle from the end of the shadow to the top of the monument. Which will give the closer height when it was measured at 1 P.M. and 5 P.M.?

48. Mechanical Design Lab. with Advanced Materials 48 Hot and Cold Water Faucet

49. Mechanical Design Lab. with Advanced Materials 49 Hot and Cold Water Faucet

50. Mechanical Design Lab. with Advanced Materials 50 Van Seat Assembly

51. Mechanical Design Lab. with Advanced Materials 51 Design Failure Examples-Challenger Space Shuttle The solid rocket booster segments are joined by a tang-and-clevis arrangement, with two O-rings to seal the joint and 177 steel pins around the circumference to hold the joint together. The zinc chromate putty acts as an insulation that under pressure would behave plastically and move toward the O-rings.

52. Mechanical Design Lab. with Advanced Materials 52 Design Failure Examples -Cubicle Failure  A large open area with a high ceiling was to be heated and cooled with three cubical units, each suspended from the ceiling by long steel rods (S.F.=17) at four corners.  The cubicles were being fitted with heat exchangers, blowers, and filters by workers inside and on top of the enclosures.  The flexibility of the long support rods permitted the cubicles to swing back and forth, and the workers sometimes enjoyed getting their cubicles swinging with considerable amplitude, Fatigue failure of a support rod caused the death of one worker.

53. Mechanical Design Lab. with Advanced Materials 53 Design Failure Examples-Press Accident  A worker lost a hand in a 400-ton punch press despite wearing safety cuffs that were cam-actuated to pull the hands.  The cause was a loosened setscrew, which delayed the hand retraction until after the ram came down.

54. Mechanical Design Lab. with Advanced Materials 54 Design Failure Examples- Engine Cover Failure When the joint is not separated P=P b +P m  =P b /k b =P m /k m =P/(k b +k m ) P b =CP C=k b /(k b +k m ) The resultant bolt force is F b =P b +F i =CP+F i F m = -k m P/(k b +k m )+F i =-(1-C)P+F i