EML 2023 – Design Process Lecture 1 – Steps of the Design Process, part 1 Lecture 2 – part 2

EML 2023 Department of Mechanical and Aerospace Engineering ABET definition of design 2 devising a system meet desired needsEngineering design is the process of devising a system, component, or process to meet desired needs. decision-making processIt is a decision-making process (often iterative), in which the basic sciences and mathematics and engineering sciences are applied to convert resources optimally to meet a stated objective. analysis constructiontestingevaluationAmong the fundamental elements of the design process are the establishment of objectives and criteria, synthesis, analysis, construction, testing, and evaluation.

EML 2023 Department of Mechanical and Aerospace Engineering Design Process 3

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EML 2023 Department of Mechanical and Aerospace Engineering Learning How to Design is Different 6

EML 2023 Department of Mechanical and Aerospace Engineering Learning How to Design is Different 7

EML 2023 Department of Mechanical and Aerospace Engineering Learning How to Design is Different 8

EML 2023 Department of Mechanical and Aerospace Engineering Learning How to Design is Different We will show you some steps of the design process and some techniques to use. It’s been said that teaching someone how to design is like teaching someone how to paint. –We can show you how to set up the easel and how to hold the brush, but it will take a lot of practice and experience on your part to become a Van Gogh. 9

EML 2023 Department of Mechanical and Aerospace Engineering Design Welcome to the world of open-ended problems. 10

EML 2023 Department of Mechanical and Aerospace Engineering 1. Recognize the Need The first step is to establish the ultimate purpose of the project via a general statement of the client’s dissatisfaction with a current situation. example – “There’s too much damage to bumpers in low-speed collisions.” –This is a general statement that does not comment on the design approach to the problem. It does not say that the bumper should be stronger or more flexible. example – The need to do something about a food packaging machine may be indicated by the noise level, the variation in package weight, or by slight but perceptible variations in the quality of the packaging. 11

EML 2023 Department of Mechanical and Aerospace Engineering 2. Problem Definition one of the most critical steps of the design process the true problem is not what it first seems the problem definition must include all the specifications for the thing that is to be designed write a formal problem statement which expresses what the design is to accomplish –include: objectives and goals musts, must nots, wants, don't wants constraints criteria used to evaluate the design 12

EML 2023 Department of Mechanical and Aerospace Engineering 2. Problem Definition example: Mobile Vehicle –Design a vehicle which can maneuver in an indoors environment. The vehicle will be operated via remote control and must be able to: 1)Travel up to a speed of 7 ft/sec on a flat, horizontal surface. 2)Climb stairs at speeds up to 2 ft/sec. 3)Carry a payload of at least 20 lbs. 4)Fit through doorways. 5)Cross obstacles up to 20" high and up to 24" across within 20 seconds. 6)Climb a slope of up to 30 degrees and cross side slopes up to 20 degrees. 7)Turn with zero turning radius. 8)Travel in any direction. 9)Cross gaps up to 24" across. 10)Total vehicle weight, not including payload should not exceed 275 lbs. 13

EML 2023 Department of Mechanical and Aerospace Engineering 2. Problem Definition design considerations 14 cost safety weight life noise styling shape size flexibility control stiffness surface finish lubrication maintenance volume liability strength reliability thermal properties corrosion wear friction processing utility

EML 2023 Department of Mechanical and Aerospace Engineering 2. Problem Definition design considerations 15

EML 2023 Department of Mechanical and Aerospace Engineering 3. Gathering of Information either no information easily found or there is an abundance of information sources: –technical reports and papers from govt. sponsored R&D –company reports –trade journals –patents –catalogs –handbooks –people (others in company ; consultants) problems in gathering information: –Where can I find it? –How can I get it? –How accurate and credible is the information? –How is the information relevant to my particular need? –What decisions result from the information? –When do I have enough information? 16

EML 2023 Department of Mechanical and Aerospace Engineering Review from Lecture 1 17

EML 2023 Department of Mechanical and Aerospace Engineering 4. Concept Generation most creative part of the design process store ideas in a design notebook approaches to concept generation: –adaptation a solution of a problem in one field is applied to a similar problem in another field (pistol grip, wine press & printing press) –analogy example: obstacle avoidance similar to potential fields –area thinking improve an existing product by concentrating on one of its important characteristics (cost, performance, function, appearance, safety, etc.) –involvement visualize yourself as being part of the mechanism 18

EML 2023 Department of Mechanical and Aerospace Engineering 4. Concept Generation approaches to concept generation (cont.): –brainstorming gather a group of people who are familiar with the general nature of the problem people say what comes to mind rules: 1.no judgements 2.the more unconventional the better 3.the more ideas the better –functional synthesis divide the system into subunits describe each subunit by a complete list of functional requirements list all the ways the functional requirements of each subunit can be realized study all combinations of partial solutions 19

EML 2023 Department of Mechanical and Aerospace Engineering functional synthesis example; can opener 20 PartFunctionRealization Subunit 11. Separate metal1. Shearing 2. Tearing 3. Fatigue 4. Melting 5. Drawing thin 6. Chemical erosion Subunit 21. Apply power1. Hand 2. Electric motor 3. Hot wire 4. Hydraulic motor 5. Flame 6. Chemical reaction 7. Mechanical vibration 8. Laser 2. Position1. Bring can to opener 2. Bring opener to can 3. Have opener built on can

EML 2023 Department of Mechanical and Aerospace Engineering 5. Concept Selection form decision matrix or decision tree time and cost are often evaluation parameters 21

EML 2023 Department of Mechanical and Aerospace Engineering Decision matrix for a crane hook Built up plates, weldedBuilt up plates, rivetedCast Hook ObjectiveWeighting Factor ParameterMag.ScoreValueMag.ScoreValueMag.ScoreValue Material Cost0.10¢/lb Manufac. Cost0.20$ Time to Make0.05hours Durability0.15experiencehigh81.2high81.2good60.9 Reliability0.30experiencegood72.1excellent92.7fair51.5 Repairability0.20experiencegood71.4very good81.6fair51.0 Overall value concept 1concept 2concept 3

EML 2023 Department of Mechanical and Aerospace Engineering 6. Communication purpose of the design is to satisfy the needs of the client must provide oral presentation and written design report continuous communication is important in order to avoid surprises importance of: drawings visual aids computer graphics models in the communications process one of the goals of this course is to provide tools to aid in the communication process 23

EML 2023 Department of Mechanical and Aerospace Engineering 7. Detailed Design and Analysis one of the goals of this course is to introduce students to analysis tools that aid in the design process other classes in the curriculum will detail design analysis tools 24

EML 2023 Department of Mechanical and Aerospace Engineering 8. Prototype and Test This course introduces you to rapid prototyping technologies that are used to create parts. The prototype is tested to see if it meets the requirements listed in the Problem Definition. 25

EML 2023 Department of Mechanical and Aerospace Engineering 9. Manufacture Part fabrication, assembly, and documentation must be optimized. 26

EML 2023 Department of Mechanical and Aerospace Engineering 10. Life Cycle Maintenance replacement parts & distribution consumables technical support scheduled maintenance patches, service packs, hardware fixes disposal, recycling 27

EML 2023 Department of Mechanical and Aerospace Engineering Design is an Iterative Process 28

EML 2023 Department of Mechanical and Aerospace Engineering Design is an Iterative Process 29

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