Introduction to the Design Process
There are many texts that are devoted to the design process.
Chap 1.
Introduction to Engineering Design
Chap 2.
Problem Formulation
Chap 3.
Information and Communication
Chap 4.
Professional and Social Context of Design
Chap 5.
Probabilistic Considerations in Design
Chap 6.
Concept Generation
Chap 7.
Project Planning
Chap 8.
Engineering Economics
Chap 9.
Decision Making
Chap 10. Optimum Design
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Accreditation Board for Engineering and Technology (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.
Welcome to the world of OPEN ENDED PROBLEMS.
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Introduction to the Design Process
no sure footing takes different survival skills
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Steps of the Design Process 1. Recognize the Need
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 lowspeed 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.
recognition of the need and phrasing of the need are often a very creative act because the need may only be a sensing that something is not right
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
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2. Problem Definition
one of the most critical steps of the design process
Recognize the Need
Problem Definition
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
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.
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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.
design considerations strength reliability thermal properties corrosion wear friction processing utility
Introduction to the Design Process
cost safety weight life noise styling shape size
flexibility control stiffness surface finish lubrication maintenance volume liability
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3. Gathering of Information
either no information easily found or there is an abundance of information
Recognize the Need
Problem Definition
sources: technical reports from Gathering of Information 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 & credible is the information? How should the information be interpreted for my specific need? When do I have enough information? What decisions result from the information?
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4. Concept Generation
most creative part of the design process
store ideas in a design notebook
approaches to concept generation:
Recognize the Need
Problem Definition
Gathering of Information
- adaptation Concept Generation a solution of a problem in one field is applied to a similar problem in another field (pistol grip, wine press & printing press) - analogy 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.) - brainstorming 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 - involvement visualize yourself as being part of the mechanism Introduction to the Design Process
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- 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 Can Opener Realization
Part
Function
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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Recognize the Need
5. Concept Selection form decision matrix or decision tree time and cost are often evaluation parameters
Problem Definition
Gathering of Information
Concept Generation
Concept Selection
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Decision matrix for the design of a crane hook.
Built up plates, welded Objective
Weighting Factor
Mag.
Score
Material Cost
0.10
¢/lb
0.8
25
8
Manufac. Cost
0.20
$
7
1.4
1200
Time to Make
0.05
hours
40
7
0.3
Durability
0.15
experience
high
8
Reliability
0.30
experience
good
Repairability
0.20
experience
good
Overall value
Introduction to the Design Process
Parameter
Mag.
Score
25
8
1500
Value
Built up plates, riveted Mag.
Score
0.8
20
9
0.9
9
1.8
2000
4
0.8
25
9
0.4
60
5
0.2
1.2
high
8
1.2
good
6
0.9
7
2.1
excellent
9
2.7
fair
5
1.5
7
1.4
very good
8
1.6
fair
5
1.0
7.2
Value
Cast Hook
8.5
12
Value
5.3
6. Communication of the Design
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
Recognize the Need
Problem Definition
Gathering of Information
Concept Generation
Concept Selection
Communication
one of the goals of this course is to provide tools to aid in the communication process
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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
Recognize the Need
Problem Definition
Gathering of Information
Concept Generation
Concept Selection
Communication
Detailed Design and Analysis
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8. Prototype Development and Testing
Recognize the Need
9. Manufacture 10. Life Cycle Maintenance
Problem Definition
Gathering of Information
Concept Generation
Concept Selection
Communication
Detailed Design and Analysis
Prototype and Testing
Manufacture
Life Cycle Maintenance
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Impediments to Design "The Right Answer" "That's Not Logical" "Follow the Rules" "Be Practical" "Avoid Ambiguity" "To Err is Wrong" "Play is Frivolous" "That's Not My Area" "Don't Be Foolish" "I'm Not Creative"
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Ethical Engineering Issues in the Future The Engineer, to uphold and advance the honor and dignity of the engineering profession and in keeping with high standards of ethical conduct:
will be honest, impartial, and will serve with devotion his employer, his clients, and the public;
will strive to increase the competence and prestige of the engineering profession;
will use his/her knowledge and skill for the advancement of human welfare.
The engineer will have proper regard for the safety, health, and welfare of the public in the performance of his professional duties.
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