eml 2023 – design process lecture 1 – steps of the design process, part 1 lecture 2 – part 2
TRANSCRIPT
EML 2023 – Design Process
Lecture 1 – Steps of the Design Process, part 1
Lecture 2 – part 2
EML 2023Department of Mechanical and Aerospace Engineering 2
ABET definition of design
• Engineering design is the process of devising a system,
component, or process to meet desired needs.
• It 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.
• Among the fundamental elements of the design process are the
establishment of objectives and criteria, synthesis, analysis,
construction, testing, and evaluation.
EML 2023Department of Mechanical and Aerospace Engineering 3
Design Process
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EML 2023Department of Mechanical and Aerospace Engineering 4
Design Process
http://architects2zebras.com
EML 2023Department of Mechanical and Aerospace Engineering 6
Learning How to Design is Different
EML 2023Department of Mechanical and Aerospace Engineering 7
Learning How to Design is Different
EML 2023Department of Mechanical and Aerospace Engineering 8
Learning How to Design is Different
EML 2023Department of Mechanical and Aerospace Engineering 9
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.
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Design
• Welcome to the world of open-ended problems.
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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.
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 12
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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 13
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.
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
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2. Problem Definition
• design considerations
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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
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2. Problem Definition
• design considerations
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
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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?
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 17
Review from Lecture 1
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
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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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 19
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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 20
functional synthesis example; can opener
Part Function Realization
Subunit 1 1. Separate metal 1. Shearing
2. Tearing
3. Fatigue
4. Melting
5. Drawing thin
6. Chemical erosion
Subunit 2 1. Apply power 1. Hand
2. Electric motor
3. Hot wire
4. Hydraulic motor
5. Flame
6. Chemical reaction
7. Mechanical vibration
8. Laser
2. Position 1. Bring can to opener
2. Bring opener to can
3. Have opener built on can
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5. Concept Selection
• form decision matrix or decision tree• time and cost are often evaluation
parameters
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
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Decision matrix for a crane hook
Built up plates, welded Built up plates, riveted Cast Hook
Objective Weighting Factor
Parameter Mag. Score Value Mag. Score Value Mag. Score Value
Material Cost 0.10 ¢/lb 25 8 0.8 25 8 0.8 20 9 0.9
Manufac. Cost 0.20 $ 1500 7 1.4 1200 9 1.8 2000 4 0.8
Time to Make 0.05 hours 40 7 0.3 25 9 0.4 60 5 0.2
Durability 0.15 experience high 8 1.2 high 8 1.2 good 6 0.9
Reliability 0.30 experience good 7 2.1 excellent 9 2.7 fair 5 1.5
Repairability 0.20 experience good 7 1.4 very good 8 1.6 fair 5 1.0
Overall value 7.2 8.5 5.3
concept 1 concept 2 concept 3
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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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 24
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
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 25
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.
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 26
9. Manufacture
• Part fabrication, assembly, and documentation must be optimized.
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 27
10. Life Cycle Maintenance
• replacement parts & distribution
• consumables
• technical support
• scheduled maintenance
• patches, service packs, hardware fixes
• disposal, recycling
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 28
Design is an Iterative Process
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection
EML 2023Department of Mechanical and Aerospace Engineering 29
Design is an Iterative Process
Problem Definition
Gathering of Information
Concept Generation
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
Recognize the Need
Concept Selection