Download - 04.EngineeringDesign
EC180 Engineering PracticeEngineering Design
Chulantha Kulasekere
Department of Electronic and Telecommunication EngineeringUniversity of Moratuwa
February 1, 2013
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Difference Engineering Design and Engineering Science
Engineering Science Problem
Problem statement is compact and well-posed
Problem has a readily identifiable closure
Solution is unique and compact
Problem uses specialized knowledge
Engineering Design Problem
Problem statement is incomplete, ambiguous, and self-contradictory
Problem does not have a readily identifiable closure
Solutions are neither unique nor compact
Problem requires integration of knowledge from many fields
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A Typical Engineering Science Problem Statement
A simply supported steel beam with a 3¨ diameter circularcross-section is loaded as shown.
Determine the maximum stress and deflection.
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Another Engineering Science Problem Statement
How much current is flowing through the circuit 0.1 sec after theswitch is closed?
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A Typical Engineering Design Problem Statement
Design a system for lifting and moving loads of up to 5000 lb in amanufacturing facility .
The facility has an unobstructed span of 50 ft.
The lifting system should be inexpensive and satisfy all relevant safetystandards.
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Summary
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ABET Definition of Design
Engineering design is the process of devising a system, component, orprocess to meet desired needs.It is a decision-making process (often iterative), in which the basicsciences and mathematics, and engineering sciences are applied toconvert resources optimally to meet a stated objective.Among the fundamental elements of the design process are theestablishment of objectives and criteria, synthesis, analysis,construction, testing, and evaluation.The engineering design component of a curriculum must include:development of student creativity, use of open-ended problems,development and use of modern design theory and methodology,formulation of design problem statements and specifications,consideration of alternative solutions, feasibility considerations,production processes, concurrent engineering design, and detailedsystem descriptions.Further, it is essential to include a variety of realistic constraints, suchas economic factors, safety, reliability, aesthetics, ethics, and socialimpact.
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The DesignsJames Watts Steam Engine
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The DesignsHenry Fords Motor Car
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The DesignsSony Walkman
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The DesignsPhilips -CD Player
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The DesignsTank Sorowwa (Maduru Oya where Old and the New Met)
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The DesignsBiso Kotuwa (A Sri Lankan Invention to reduce water pressure)
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The DesignsThe Toilet (We were the first and not the French)
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The DesignsFor discussion
How does the anti lock braking system work?
Explain the shape of an aircraft wing
Why is a differential needed?
What is the use of the independent suspension system in a car?
Explain the fabrication of the bullet proof vest
Why do cement bricks have holes in the middle?
How does a thermos flask work?
How does a touch screen work?
How do you take a picture with a camera?
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Our Design History in the Recent Past
Heavy dependence on foreign technology
Heavy dependence on imported machinery
Heavy dependence on imported consumer products
No clear support from state
Why?
Local inventors were not supported by Colonial Rulers
No local development in-line with technological development tookplace during last 200 years
No significant contribution from the educated sector to improve thetechnology generation in Sri Lanka
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Characteristics of a Design Engineer
ability to identify problems
ability to simplify problems
creative skills
sound technical knowledge
sense of urgency
analytical skills
sound judgment
decisiveness
open mindedness
ability to communicate
negotiating skills
supervisory skills.
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Characteristics of a Design Engineer
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Why Engineering Design is Important
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Thinking Outside the BOXConnect the dots using 4 straight lines without lifting the pen
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Thinking Outside the BOXNow connect the dots using 3 straight lines without lifting the pen
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Thinking Outside the BOX4 lines
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Thinking Outside the BOX3 lines
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Some Software Tools used in Engineering Design
Project management tools (eg. Planner, MS Project)
Mind mapping tool (eg. Freemind, MindMeister, XMind)
Circuit design EDA (eg. OrCAD, Altium Designer, Proteus)
Solid Modeling (eg. SolidWorks, Medusa, FreeCAD, Pro Engineer)
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Ten Step Model of the Design Process
1. Recognizing the need
2. Defining the problem
3. Planning the project
4. Gathering information
5. Conceptualizing alternative approaches
6. Evaluating the alternatives
7. Selecting the preferred alternative
8. Communicating the design
9. Implementing the preferred design
10. Evaluating the design
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Step 1: Recognizing the Need
Communicate with the client (communication is the key)
Identifying the client needs against wants(customer requirements matrix.pdf)
A requirement is something the product should do/produce or aquality that it must have.
A customer requirements matrix can be filled if necessary.
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Step 1: Recognizing the NeedDifferent Perspectives on Requirements
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Step 1: Recognizing the NeedA typical example1
Sandra: “Jane, we need you to design a stronger bumper for our newpassenger car.”
Jane: “Why do we need a stronger bumper?”
Sandra: “Well, our current bumper gets easily damaged in low-speedcollisions, such as those that occur in parking lots.”
Jane: “Well, a stronger bumper may be the way to go, but theremay be better approaches. For example, what about a moreflexible bumper that absorbs the impact but then returns toits original shape?”
Sandra: “I never thought of that. I guess I was jumping toconclusions. Let’s restate the need as “there is too muchdamage to bumpers in low-speed collisions.” That shouldgive you more flexibility in exploring alternative designapproaches.”
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Step 2: Defining the Problem
Goal
Objective
Constraints
Use of design Notebooks
Use of Mind Map tools to define the problem
Describe the problem by writing a problem statement. Your problemstatement must answer three questions:
What is the problem or need?Who has the problem or need?Why is it important to solve?
You can elaborate these ideas and gather information later
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Design NotebooksPart of Leonardo daVinci’s notebook
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Design NotebooksPart of Thomas Edision´s notebook
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Design Notebooks
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Step 3: Planning the Project
Using a tool to develop a Gantt Chart
Identifying the milestones and the costs involved.
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Step 4: Gathering Information
Information sources to do a background research
Verify the accuracy
Organize and categorize the collected information
To make a background research plan, a road map of the researchquestions you need to answer:
Identify questions to ask about your target user or customer.Identify questions to ask about the products that already exist to solvethe problem you defined or a problem that is very similar.Plan to research how your product will work and how to make it.Use this Background Research Plan Worksheet to help you developyour own plan.
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Step 5: Conceptualizing Alternative Approaches
Create design options (deal with objectives and constraints)
Concurrent engineering: which is sometimes called SimultaneousEngineering or Integrated Product Development (IPD), is a workmethodology based on the parallelization of tasks (i.e. performingtasks concurrently). It refers to an approach used in productdevelopment in which functions of design engineering, manufacturingengineering and other functions are integrated to reduce the elapsedtime required to bring a new product to the market.
Totally different approaches should be analyzed and pruned (eg.AnalyzeaPhysicalProduct.pdf)
The alternatives can be based on new ideas, examining existingsolutions to come up with better designs or based on creating andusing analogies (applying design methods applied to other artifacts).All of these will enrich the creative process.
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Brainstorming as a Tool for Idea Generation
Composition:
Small team (5 to 10 members allowing individual ideas not to behidden)Diverse team: Select team members from different backgrounds.people with little and more experience
Logistics
Short meetings: brainstorming should be less than an hourRecord meetings: Identify a person to record the ideas on a board etc
Meeting protocol:
Group members should be considered equal: no hierarchyNonjudgmental: nothing is stupidQuantity over qualityBuild ideas: create new ideas by combining and building other ideas
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Methods for Generating New Ideas
Checklist: Is a tabulation of ways that an objective can be achieved.
Attribute Listing: table of attributes of the device considered and thepossible values or solutions for each attribute. Attribute values can becombined in different ways to generate new ideas as well.
Morphological analysis: All the permutations of the attribute listing iscalled a morphological analysis.
Ideation
This creative process of developing multiple ideas to solve a single problemis called ideation.
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Example of Generating Alternatives via New IdeaGeneration (1)
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Example of Generating Alternatives via New IdeaGeneration (2)
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Step 6/7: Evaluating/Selecting the Alternatives
Determine the effects and impact of each alternative
Use an objective evaluation methods (using formula, probability, orscience principle)
The Universal Design Criteria can also be used: Elegance,Robustness, Aesthetics, Cost, Resources, Time, Skill required, Safety.
Note that alternatives should be compared across a common set ofcriteria
Collect critiques via a decision matrix eg. DecisionMatrix.pdf
The answer to the above lies on the different feasibilities learnedbefore: Technical, Economic, Fiscal, Social/political/environmental.
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Universal Design CriteriaElegance. An elegant design solution is simple, clever, or ingenious. Itmight have fewer parts to wear out or fail. It might combine solutionsfrom different areas in an inventive way not seen before. All gooddesigners strive for elegance in their designs.Robustness. A robust design is unlikely to fail, even when used inconditions more severe than it was designed for. It is sturdy orresilient, perhaps bending, but not breaking in hard use.Aesthetics. If everything else is equal, people prefer a solution that istasteful and pleasing to look at.Cost. What will it cost? Can the target user afford the solution? Doyou have enough money to build your prototype?Resources. Do you have all the materials and equipment you need foryour engineering project, or will you be able to obtain them quicklyand at a very low cost?Time. Do you have enough time to complete your design and make itbefore the due date? Allow time for doing additional research andfixing problems. It is very rare for everything to work correctly the firsttime.Skill Required. Do you have the skills to build and implement yoursolution, or can you learn them in the time available?Safety. Is your solution safe to build, use, store, and dispose of?
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The Funnel
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Example Analysis
Design of a portable wheelchair ramp.
Requirements: Meet the disable people act, The ramp must beadjustable to slopes between 1:20 and 1:12, have a minimum width of36 inches., ramp must be inexpensive, should bewheelchair-transportable.
Lets say the brainstorming activity yielded: an inflatable ramp, afoldable stainless steel ramp, fiberglass ramp
In a case such as this the analysis might consist of the followingquestions:
Can the ramp be made adjustable to slopes between the values given?Can the ramp be made with a width of at least 36 inches?Can the ramp with the above specifications bewheelchair-transportable?What is the cost of the ramp with all of the above characteristics?
Use the techniques learned to suggest an analysis.
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Step 8: Communicating the Design
Use of language to bridge the gap between the ´design swamp´ to´land of the client´
Documentation methods which have to be followed.
Balance between the technical content and the marketing content tomeet the needs of the client.
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What issues do you see with the lack of communicationwithin the design groups?
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Design Innovation Strategies
Concurrent engineering: Concurrent engineering is a workmethodology based on the parallelization of tasks (i.e. performingtasks concurrently). It refers to an approach used in productdevelopment in which functions of design engineering, manufacturingengineering and other functions are integrated to reduce the elapsedtime required to bring a new product to the market.
Re-engineering (redesign): refers to a fundamental rethinking andradical redesign of a system.
Reverse Engineering: refers to the process of taking apart an object orsystem to see how it works and design based on your findings.
Failures are the pillars of success
A glue that did not stick well enough was nearly abandoned after a lot ofresearch but became the solution to 3M post-it notes which took the worldby storm.
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Mode refined way of looking at Design StrategiesTop-Down
Also called ¨functional decomposition¨
implementation details considered only at the lowest level
top-down design, is not so clean and linear in practice
Often implementation-level commitments are made at high levels inthe design process
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Mode refined way of looking at Design StrategiesCase Based
Research a specific, similar design case study
Model your process on that
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Mode refined way of looking at Design StrategiesIncremental Redesign
Find an existing design and ¨unravel¨ the design from the bottom up
Modify as required
Detailed and least global aspects of the design are explored andredesigned, if necessary, first
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Mode refined way of looking at Design StrategiesIncremental Redesign
An iterative top-down approach
First a rough, approximate and general design is completed
Then we do it finer, more exact and more specific
This process continues iteratively until the complete detail design indone
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Mode refined way of looking at Design StrategiesBottom-up Design
Opposite of top-down
Start at the bottom with detail design
To do this, you must have some idea of where you are going. So,often this becomes a Hybrid Design
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Mode refined way of looking at Design StrategiesHybrid Design
Combines aspects of both top down and bottom up
More practical design approach then pure top down
Start with a top-down approach, but have feedback from the bottom
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Mode refined way of looking at Design StrategiesExplorer Method
Typically used for new design ideas or research
It is useful in initial design and specification stages, and is often usedwhen in ´unfamiliar territory´
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Example Exercises
5E method of addressing the supermarket organizer
Building a single heat element coffee maker(http://www.engineerguy.com/videos/video-coffee-maker.htm)
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