Welcome to an IncreDIble Illinois
Structure Workshop
Please check in! 12:30- 1:00 p.m.
Brainstorming: One idea per Post it®:
"Structure"
1. "What exactly IS a “structure”? Can you give examples? What other words
come to mind ?
2.List questions you want
answered today
3. Then add your Post it®s
to designated papers on wall
What is a Structure?
• A structure is anything made up of a number of parts
that are held together in a particular way and has a
base or foundation.
• All structures give support or provide a framework.
You can find structures everywhere. Bridges,
buildings, chairs, shoes, plants, spider webs, tables,
and even your own body are all structures. A
structure's shape, size, and what it's made of depend
on what the structure does and how strong it needs to
be.
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Form and Function
Every structure has form and function. Form and Function are
interconnected.
The shape (or form) of something affects its purpose (or function).
Something with a certain shape can have more than one purpose or
function.
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Forces of Tension and Compression
Every structure is affected by forces.
The force of one structure can affect another.
The affect can go back and forth with a push and pull force.
Compression and Tension are examples of push and pull forces.
Compression : the state of a material pressed together or forced into
less space.
Tension : a stress on a material made by the pull of forces extending
outwards.
Structures in
the Real World
You can find inspiration all around you if you just look
6 Flags – Texas Giant
6 Flags – G Force
6 Flags – Bob Sled
6 Flags – Judge Roy Scream Roller Coaster
Construction Project – Masonry Scaffolding
DFW Airport – Tower Cranes used constructing new Terminal
Six Flags – The Titan
DFW Airport – Doppler Radar
Six Flags – Mister Freeze
Electrical Wire Transmission Tower
Six Flags Oil Derrick
DFW Airport - Scaffolding holding up concrete forms
Basic
Concepts
&
Definitions
Intro to teaching
basic structure
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Wood
Jigs
Forces
Glue
Tools and More Tools
Construction Area
This year’s Challenge
The Duct Tape Challenge
Summary
Construction Area
A large open table, where team can place building jigs,
weigh wood, saw and cut materials, assemble, & finish
structures.
Cover the table top (sheet of thick plastic or masonite)
Make sure that work areas are kept well ventilated,
especially when teams are using glues with harmful
vapors.
Cutting Tools and Equipment
Helping teams learn
about wood characteristics
• Wood
– Wood comes in a variety of dimensions (sticks and planks).
– Hobby stores carry balsa and basswood (basswood generally denser and
heavier)
– USA Balsa and SIG has a large assortment of wood (www.sigmfg.com)
– Factors to consider
• Weight
• Strength
• Ease of use
Wood Hands on
• Examine the wood for
– Texture
– Grain
– Smoothness
– Kerf marks
• How porous is it?
• How easy does a stick bend?
• How much does it weigh?
Sanding Balsa Wood prior to sorting
Comparison of woods
Species
Wt Stiffness Bending
lbs/cf Strength Strength
Compression
Strength
Balsa
8
72
70
75
Balsa
14
156
161
149
Spruce
28
230
260
289
Bass
wood
26
261
288
288
Wood Characteristics
• Anistropic means having properties that
differ depending on direction
• Wood has grain to it and will react
differently depending on the grain
• Consider how grain affects how wood
reacts and build your structure with this
in mind
Moisture
• Wood absorbs moisture from the air
(especially balsa wood)
• When weight is a consideration teams may
want to consider ways to remove moisture
from their structure
• Many teams try to control the moisture
absorption by the wood
• Others try to remove moisture prior to weigh
in
Moisture
• Teams may find that certain glues
degrade when exposed to extreme heat
(thus the structure is weaker after
drying)
• Teams should brainstorm, quantify and
test any techniques they consider for
removing moisture from their structure
General Definitions
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Structure
Column
Brace
Member
Stress / (Forces)
Stress (Forces)
that act on a structure
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Compression
Tension
Shear
Twisting/ Rotation
Compression
Compression forces try to “crush” things
Compression
Compression forces also try to buckle things
Tension
Tension forces try to pull things apart
Shear
Shear forces try to “break things”
Hands on
• Take a 12” piece of wood
– Stand on its end and push down on it
You are putting the wood in compression
– Now try to pull it apart
– Now lay it ½ over the edge of your table
and press down on the outside piece
More Definitions/Concepts
• Buckling load
– The amount of weight required to cause a
structure to fail
• Critical Length
– The length where wood no longer bends
but crushes
Law of Squares (cont)
• If I have a 12” column and a 4” column
constructed from the same material the
4” column will hold 9 times as much
weight as the 12” column.
• 4” = 1/3 of 12”. So Invert 1/3 to get 3
and then square it to get 9
Hands On
Law of Squares
Balsa
Balsa
Balsa
Estimate Actual
Weight
Weight
Weight
Weight
Held
Held
Estimate Actual
36”
X
X
18”
12”
Demonstrations
The next few slides come from a
computer program that allows a user to
build a structure on screen and then test
the structure. We are using screen
shots form this program to demonstrate
a few of these concepts
Simple 4 column 8” tall structure with compression load
110.74 grams
Held 110 grams of weight
Simple Tower – horizontal braces in middle
444.68 grams
Tested to failure
4 x 110 = 440 grams
Columns are now braced twice (1/3 length)
899.23 grams
Tested to failure
Not testing to failure
Adding another force acting on the side of the structure (only 1 gram)
Disaster strikes
Correcting the problem
The Diagonal Braces kept the structure stable
Bracing
• Horizontal Bracing
– Typically – horizontal bracing is used to
resist buckling in a column
• Diagonal Bracing
– Typically – diagonal bracing resists twisting
in the structure (adds stability)
35.05 grams
With compression force applied straight down – column held 35.05 grams
140.38 grams
4 x 35 = 140
140.38 grams
Total Column height is 12”
140.38 grams
Total Column height is 12”
Cutting
• Cut (don’t “squash”) the wood
• Cutting can damage cells at end of the
piece
• Think of ways to keep that from
happening
Cut by rocking blade straight back and forth
Helping teams learn about glue
characteristics
• Glue
– Expose team to many different types of
glue, read directions
• Hot glue
• Super glue
– CYANOACRYLATE (pronounced "sigh-ano-ackrelate") adhesive specially formulated to meet
the tough demands of building and flying model
airplanes. Available in three different viscosities.
Each viscosity has different application and cure
characteristics.
• Wood glue (Gorilla glue)
• Epoxy
• Carpenter’s wood glue (Elmer’s)
– Factors to consider
• Strength
• Drying time
Provide Adequate Ventilation !
• Weight
• Ease of use
Pill bottles to clean CA
Glue Tips
Acetone
Gorilla Glue
Airplane Glue
Wood Glues
Contact
Cement
CA “Super” Glues
Old Razor - to clean glass
Extra CA Glue Tips
Glass Surface to build on
Glues
Glue Testing Device
• Teams may want to construct testing devices to test the
different types of glues.
• Plans for a device for testing glue strength are available at :
http://www.specializedbalsa.com/strength_test_instructions.php
Glue Safety Rules
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No Horseplay
Read and Follow Safety Instructions
If you can’t use it safely – don’t use it
Don’t mix glues together
If using CA Glue – keep Acetone on
hand
Tools & Safety
• Tools such as saws, X-acto knives, and
razors can be used to cut wood. When any
sharp tool is used, sharp edges should
always be directed away from flesh.
• Let team members experiment with cutting,
sawing, and sanding wood with various tools.
Encourage them to explore any tool they
think will allow them to build better/easier.
Useful tools
• X-acto fine tooth razor saw
• Plastic holder holding a single edge razor blade
Other useful building items:
• Flat tile or mirror
• Building square
• Emery boards, sand paper
• small aluminum mitre box for razor saw
All tools should be readily available to consumers
and of the team’s own choosing
Level/Straight Edge
Levels are usually used to
see if a surface
is perfectly level (meaning
it won’t tilt up or
down). They can also be
used to draw a straight
edge.
Other Useful Things to Have
• Gram scale accurate to 0.1 grams
– Permits weighing wood and completed
structures
– Ohaus has a low-cost one (<$90) but
you can probably borrow or get access to
one (school lab, workplace, post office,
police station (ask for confiscated scales)
– Ebay frequently has “deals”.
• Hair Dryer
– Speeds up glue drying
– Removes excess moisture from wood
(weight)
More Useful Things to Have
• Structure Tester
– TM or other parents are allowed to construct a
tester for the team
– Instructions are available
(http://www.farnorthdi.org/TRAINING/How_to_
build_tester.doc)
– Try borrowing a tester
• Weights
– Olympic style (2 inch hole)
flat metal weights
Woodworking
Basics
Measuring Tools
Clear Plastic Ruler comes in handy when you’re cutting sticks of balsa
wood. When you mark the balsa wood, make sure of three things:
One, make sure that you have the edge of the ruler aligned with the edge
of the stick.
Two, make sure you mark the length with a single dot. Otherwise, if you
mark it with a line, it will be crooked for sure.
Three, once you’ve measured it, be sure to measure it again. There is an
old woodworking saying “Measure twice, cut once”. That’s because it
is a lot easier to fix a mistake before you make it than afterwards.
Woodworking
Basics
Measuring Tools
Top: T square is used to put one piece of wood at a right angle to
another.
Bottom: L Square
Woodworking
Basics
Measuring Tools
• A combination square is used to mark a line
lengthwise down the middle of a long piece of
wood. A combination square consists of two main
parts. The first part is a foot long metal ruler with a
notch at the end to hold a pencil. The second part is
an adjustable steel bar that slides. This lets you
adjust where you want the mark to be.
Jigs
Jig (template)
• A gauge, pattern, or mold used as a
guide to the form of a piece being made
• Jigs can be 2 dimensional or 3
dimensional
• It is not necessary to use a Jig
• A Jig helps you to build consistently
• ANY jigs used by the team must be
BUILT by the team
Plastic and
brass square
tube from
Hobby store
Aluminum Square Tube
from hardware store
Steel keystock
from hardware
store
1x1 from lumber yard
Sample materials that can be used to make templates
This Year’s Challenge
E: The Inside DImension
If walls could talk….!
Educational Focus: Architectural Design, Structural
Engineering, Construction, Research, Innovation
and Design Process, Mathematics, Theater Arts,
Teamwork
AAAAHHHHHHH!!!!!
Inside DImension
Structure Specification Details (applies to both structures)
– 7 1/2” ≤ height above tester surface ≤ 9”
– Combined wt. of both structures ≤ 14.0 grams
– Weight difference between 2 structures ≤ 2.0 grams
– fits over 2” cylinder
– Any wood allowed as long as it is just natural wood
(no plywood, laminates, composites, coatings)
– Glue may only be used as an adhesive
– Glue may not extend beyond ¼” of a joint
Closeup of a Tester
• Base
alone
• Loaded with
structure, presser
board & weights
Presser Board
supported
about 1”
above
corner posts
by
structure
The Presser Board & weights are fully supported by structure
Tester setup
Top of red tape is 1” below top of pole
Metal Weights
Pressure Board
Team Designed Structures
7.5” to 9”
Floor surface
Traditional Tester
2nd structure inside first structure
Supporting Blocks
More Hands on
The Duct Tape Challenge
Focus: The Testing process for structure challenges
Architectural Design, Structural Engineering, Construction, Teamwork.
The Destination: Where This Challenge Will Take You!
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One of the keys to building REALLY strong structures is to spend the
time ‘following through on the details’. Without doing so could turn a
wonderfully constructed structure into a ‘leaning tower of Pisa” unless it
is checked to be sure it is “plumb”.
The process of placing weights on the structure is an area many firsttime structure teams do not give sufficient attention.
What happens if all the parts of the structure that have to carry “load”
do not actually contact the upper and lower surfaces of the tester?
What happens when the weights are placed on the structure? Is there a
way to anticipate those things and plan for them?
This goal of this challenge is to help teams anticipate these questions
and develop a team plan. Teams that plan, practice and brainstorm
issues in advance will have a plan – and a contingency plans- so they
don’t have to make “snap decisions” at tournament that they might
regret.
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Your team will:
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􀂐 Build and test a Structure made completely of Wood and Tape. 􀂐
Time Limit: The team must complete the solution on site within one hour which will include weigh-in and testing of the
structure.
Team Materials Required: Teams will provide their own duct tape and masking tapes, and may prefer to bring a ruler for
their use. The pre-cut balsa wood for the structure, a “template” and “jig”, gram scale for weighing it, testing device and
Olympic weights will be provided by the Trainers.
Roadmap for Success: Teams must work together and plan a strategy in order to successfully solve this Challenge!
a. Team will open kit and construct the structure.
b. When complete they can raise their hand and let the Trainer know they are ready for “weigh-in”
c. The team will test the strength of their Structure by stacking weights on the Pressure Board of a Structure Tester while
the Structure rests on the Tester Base.
d. The testing will result in an Official Weight Held. Normally, at each level of competition, the Structures with the highest
Official Weight Held score will receive 160 points. The score for all other teams in that Level would be based on the
percentage of that Official Weight Held for that competition Level. In this challenge, the focus is not on the weight held
but on how well the teams can place the weights on their structure so that it will hold as much weight as possible.
Building the Structures: Specifications
a. A “level playing field” has been ensured for all teams in regard to the design and the materials of the structure. The test
here will be in how they construct and TEST the structure.
b. Height of Structures: Each Structure must have a minimum height of 7.5in. (19.1cm) and a maximum height of 8 in.
(21.9cm).
c. Weight of Structures: The weight for Middle and Secondary team Structures may not exceed 40 grams The
weight for all other levels is unlimited but the teams will want to know what it is for their records and to note the efficiency
of their structure.
d. The Structures are designed to support weights stacked on the Pressure Board of the Structure Tester
e. The Structures must have an opening, running their entire height, which can accept a circular column with an outside
diameter of 2in. (5.1cm). The Structure must rest upon the Tester Base and fit over the Safety Pole. The Structure must
fit entirely on the Tester Base and may not touch any of the Safety Supports or the Safety Pole.
f. The Structures will be constructed using ONLY natural Wood and Tape- Duct tape and Masking Tape; no other
materials will be allowed. The Balsa Wood included in the kit was not weighed in advance and has not been screened in
any way. Pieces were placed randomly in the kits.
Laminates in the Structures. Team may use duct tape as a laminate in this structure but should realize it will add to the
weight of the finished product.
Jig provided is a simple block of wood with L square.
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Weight Placement
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Practice, practice, practice
Have a plan
Be prepared to modify your plan
What will happen when you mishandle a
weight
• How can you protect your fingers from
being pinched?
Analyzing
• Analyze broken structure to determine
what failed
• Use safety shields and watch what
happens – make notes
• Analyze the video tapes
• Use a sports camera
• Incremental testing
Analyzing tested structures is the best way to discover where you can improve
Design Considerations
• Record pertinent information about
every structure
– Glues used
– Materials used
– Weight and weight held
• Don’t change too many variables
between tests
Don’t change too many things at once
What’s
the Secret?
Thoughts on
the Tournament
Tournament Day
Considerations
• How are your going to transport your
structure safely to tournament
• What supplies do you need for repairs?
• What will you store your structures in
when you turn them over to the
Appraisers
Tournament Day Thoughts
. . . . . (continued)
• Before tournament do your own mock
check in with the structure – does it
meet the challenge specifications
• Do you think you need a spare
structure?
Tournament Day Thoughts
Closing Thoughts
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Good structures look good
Keep it simple
Keep in Level
Keep it Well-glued
Have Fun!
Questions?
Good Luck!
Acknowledgements
Victor Tom
Pre-engineering Corp (pictures)
Bill Allen
Reggie Bunis
Ernie Chang
Special thanks to Charles Compton, Arlington TX, for
creating the structure of this presentation and offering
suggestions, corrections, technical
explanations and commentary