The Engineering Design “Recipe”The Engineering Design “Recipe”

Engineering Design Recipe

Although the design Although the design process is very process is very

structured, it should structured, it should not inhibit creativity!not inhibit creativity!

Looping and iterations Looping and iterations are common!are common!

Separates “designing” Separates “designing” from trial and errorfrom trial and error

Engineering Design…

……is problem solving!is problem solving! Problem: My cell phone battery is dead Problem: I agreed to attend two different

meetings during the lunch hour Define the problem, generate ideas, select a

solution….but no building or evaluating

Problem: “Design” a way to conveniently and effectively roll up the rim to win.

Problem Definition

Ask questions! Ask questions as if you were the user AND the

designer User: will it fit in my pocket? Designer: what kind of material will it be made of?

First brainstorming session should be to come up with questions to better clarify the problem

How big can it be? Does it have to work on a full cup? What type of people will be using it? What does ‘convenient’ mean? What does ‘effectively’ mean? How much should it cost?

Problem Definition

Clarify objectives!Objectives of a design are

Goals you work towardWhat the design “should” be

“The design should be easy to use” “The design should be inexpensive”

Design options may meet an objective perfectly, or they might only meet an objective part way

Problem Definition

Establish constraints! Constraints of a design are

Strictures or limitations on the design What the design must be

The design must cost less than $500 to purchase The design must be able to carry at least 500 g of sand

Must be able to answer yes/no The design must be lightweight not a constraint The design must weigh less than 10 kg constraint

Listing Objectives and Constraints

Easy to use Lightweight Portable (fit in your pocket) Safe (no sharp edges or

open cutting surfaces) Made of non-toxic

materials Able to open enough of

the rim to read the printed words

Able to open the rim without mangling the cup

objective

constraintobjective

constraint

objective

objective

objective

A method of rolling up the rim should be…A method of rolling up the rim should be…

Ordering Objectives

Different designs result from the same problem “Design a device that enables people to reach

heights they would be otherwise unable to reach”

Final design will depend on which objectives are MOST important

Objectives: Portable Inexpensive Aesthetically pleasing Durable Safe for people of all ages Wide variety of uses

Ordering Objectives

Pairwise Comparison ChartPortable Inexpensive Aesthetically

pleasingDurable Safe for

people of all ages

Wide variety of uses

Score

Portable X 1 0 1 0 1 3

Inexpensive 0 X 0 0 0 0 0

Aesthetically pleasing

1 1 X 0 0 0 2

Durable 0 1 1 X 0 1 3

Safe for people of all ages

1 1 1 1 X 1 5

Wide variety of uses

0 1 1 0 0 X 2

Measuring how well objectives are met (metrics)

Constraints are yes/no so they are either met or they aren’t

Objectives may be met part way need to assign a “number” value

Metrics: a scale that the designers agree upon to measure how well design alternatives meet objectives Should be unambiguous Should actually measure what you want to measure Should be repeatable

Metrics

Metric scales can be based on actual numbers Objective: inexpensive to buy Metric scale

< $500 scores a 10 >$1000 scores a 1

Metric scales can be subjective Objective: safe to use

Likely to harm self or others scores a 1 Impossible to harm self or others scores a 10

Metric scales can be based on actual lab tests Objective: durable in all types of weather Lab test: build a scale model or prototype and subject it to simulated

wind, rain etc. and assess the damage after a specific amount of time

Total destruction scores a 1 Totally intact scores a 10

Applying Metrics

A method of rolling up the rim objectivesEasy to useSafeOpens enough of rim to read wordsDoesn’t mangle cup

Applying Metrics

Metric for “easy to use” Requires extensive

training 0 Requires one

demonstration 5 Intuitive 10

Metric for “safe” Likely to harm self or

others 0 Possible to harm self or

others 5 Impossible to harm self

or others 10

Metric for “opens enough of rim” <1 cm 0 1-3 cm 5 >3 cm 10

Metric for “doesn’t mangle” Words are

indistinguishable 0 Words can be made

out 5 Words are clear 10

Finishing Defining the Problem

When you run out of questions, you can continue gathering information by searching literature “State of the art” searches how do similar

designs work? Web searches, patents, vendor information

Expert information talk to someone with experience in the area

Sometimes more efficient than wading through documents Visual brainstorming looking at images related to

your design problem can stimulate thought process Google images, magazines, Science TV

Next Stage: Generate Ideas

Literature searches Literature searches can stimulate can stimulate creative ideascreative ideas

Identifying Identifying functions and functions and

means can also means can also help start the help start the

creative processcreative process

Functions

Establish Functions!Functions of a design are

Things the design will doUsually characterized with a verb-noun pair

The design will support a loadThe design will dampen oscillationThe design will contain liquid

Try not to worry about how you will achieve the function yet

Help with establishing functions

Imagine the object disappearing Imagine if a bookshelf wasn’t there, what would

happen? The books would all be on the floor in a big heap!

Function: support books Secondary function: organize books

Think of the object as a black box and examine inputs and outputs The inputs on a radio are: channel/volume

selection, power, and a radio frequency signal. Outputs include: sound, indicator lights and heat.

Function: convert signal to sound Secondary (unwanted) function: generate heat

Morphological Charts

Brainstorm ways to achieve functions and featuresBrainstorm ways to achieve functions and featuresFeature or function Means

Cut rim Scissors Knife Laser Razor blade Teeth

Unroll rim Squeeze and pull

Heating to expansion Momentum Wedge and

slide

Non-toxic material Plastic Cardboard Metal Glass Wood Nylon

Portable Key chain Zipper pull Attached to cell phone

Part of your body

More on Brainstorming

Need a specific problem statement How can we achieve this function? How is this function achieved in other situations? How can we meet this objective perfectly?

Anything goes! Do not discuss until after session. Write everything down!

Linking seemingly unrelated things is key to good brainstorming

Establish Design Alternatives

Choose from your options in the morphological chart and use some creativity to put them together

A method of rolling up the rim design optionsFingers/teethKnife/fingersPlastic RimRoller

Next Stage: Select a Solution

A good solution A good solution must fulfill must fulfill

requirements, requirements, meet with meet with

deadline, and be deadline, and be produced with produced with

available available resources.resources.

Applying Metrics

Easy to use

Safe Opens enough

Doesn’t mangle

Score

Fingers & teeth

6 9 1 5 21

Knife & fingers

5 2 10 10 27

Rim Roller

5 10 5 10 30

Doesn’t account for relative importance of objectives!Doesn’t account for relative importance of objectives!

Decision Matrices

First, check to see if alternatives meet all constraintsConstraints: portable (fit in pocket) and

made of non-toxic materialsAlternatives that meet all constraints can

be entered into a decision matrixDecision matrices involve weighted

objectives

Pairwise Comparison Chart (again)

Easy to use Safe Opens enough Doesn’t Mangle Score

Easy to use X 0 1 0 1

Safe 1 X 1 1 3

Opens enough 0 0 X 0 0

Doesn’t mangle 1 0 1 X 2

Apply weightings (subjective, discuss with group). Total Apply weightings (subjective, discuss with group). Total weighting should add up to 100%.weighting should add up to 100%.

Safe: 40% Doesn’t mangle: 30% Easy to use: 20% Opens enough: 10%

Decision Matrix (with weighted objectives)

Fingers & teeth Knife & fingers Rim Roller

Objectives Weight Score Weighted Score Score Weighted

Score Score Weighted Score

Easy to use 20% 6 1.2 5 1.0 5 1.0

Safe 40% 9 3.6 2 0.8 10 4.0

Opens enough 10% 1 0.1 10 1.0 5 0.5

Doesn’t mangle 30% 5 1.5 10 3.0 10 3.0

TOTAL 100% 6.46.4 5.85.8 8.58.5

Establish Design Specifications

SpecifyMaterialsSizesTypes of motorsSizes of pumpsMethods of attachmentSize of holesEtc, etc, etc.

Next Stage: Build the Design!

After all the After all the question asking, question asking,

brainstorming brainstorming and evaluating, and evaluating,

you should have you should have a good idea of a good idea of

how the how the components will components will

go together.go together.

Next Stage: Evaluate!

Test the design in Test the design in conditions similar conditions similar

to actual to actual conditions. conditions.

Modifications Modifications may be required, may be required,

or alternatives not or alternatives not previously previously

considered may considered may become obvious!become obvious!

Final Stage: Communication

Written and oral Written and oral reportsreports

Include all Include all options as well options as well as final option to as final option to show thought show thought process and process and consideration for consideration for all alternativesall alternatives

Clear, concise, to Clear, concise, to the point, well the point, well organizedorganized

Working in Groups

Engineering is multi-disciplinary!Communication is keyDealing with conflict

AvoidanceSmoothingForcingCompromiseConstructive engagement – the only way to

consistently get “win-win” results

Making a plan and sticking to it!

Procrastination can lead to stress and sub-par designs!

Be aware of tasks that can overlap and tasks that must be completed before moving on

Set deadlines for tasks, assign them to group members, and stick to the plan!

Gantt Charts are visual representations of task breakdown, overlaps, and critical path

Sample Gantt Chart

Summary

Ingredients:Ingredients:

Brainstorming, Brainstorming, objectives, constraints, objectives, constraints, functionsfunctions

Pairwise comparison Pairwise comparison charts, metrics, decision charts, metrics, decision matrices, morphological matrices, morphological chartscharts

Project planning, Project planning, communication, communication, creativity, patiencecreativity, patience