Structure and Forces How does understanding the effect of forces, properties of building materials, and design characteristics contribute to structural strength and stability?

1) p (Natural vs. Manufactured) APK and notes 2) p (Mass Structures - advantages and disadvantages) Monitoring and Clarifying checklist– 3) p (Frame Structure - advantages and disadvantages) Inferring use chart 4) p (Shell structure) Questioning w/s 5) p280 (Mix and Match) Questioning – Divide page in half 6) p (Function) Choose Strategy 7) p (Joints) Choose Strategy

A one story building, has no doors or windows. How do you enter?

Types of Structures: Origin 1)Natural Structures (p ) – not made by people -living and non-living You have 3 minutes to list as many natural structures as you can as a team.

Types of Structures: Origin 2) Manufactured Structures (p271) – made by people -big and small - often modelled after natural structures You have 3 minutes to list as many manufactured structures that were modelled after natural structures as you can.

Shell Structures p Divide your page in half. On one side write ANSWERS and the other QUESTIONS.

Shell Structures p What are questions you could ask about the following “answers”? - objects that use a thin, carefully shaped outer layer of material to provide their strength and rigidity

Shell Structures p parachutes, eggs, igloos, box, cream puffs, bubbles, turtle shells

Type of Structure: Design - completely empty so make great containers - use very little building material

Type of Structure: Design -flat materials do not easily form shells -careful assembly is required - tiny weaknesses from formation, material, outside forces can easily damage the shell

Identify the types of structure Tent Dam Spider web Boat Skull Pop can Bridge CD case Solid plastic wing Wood wing Type of Structure Quiz

Name the type of structure (shell, mass or frame) that is most likely to fail because 1)The material it was built from has small cracks or weaknesses 2) The weight of the structure caused the ground underneath it to shift 3) The outside walls were tilted slightly by an earthquake

Identify the types of structure Tent (combination shell/frame) Dam (mass) Spider web (frame) Boat (combination frame/shell) Skull (shell) Pop can (shell) Bridge (frame) CD case (shell) Solid plastic wing (mass) Wood wing (combination frame/shell) Type of Structure Quiz

Name the type of structure that is most likely to fail because 1) the material it was built from has small cracks or weaknesses (shell) 2) The weight of the structure caused the ground underneath it to shift (mass) 3) The outside walls were tilted slightly by an earthquake (frame/shell)

Pinocchio nose Pinocchio nose challenge (longest free-hanging nose extending from the face, using only newspaper (take what you need but use what you take) masking tape (no sticky side of the tape can touch the skin) String 20 minutes

Marshmallow Challenge In order to get to know the people in your company, your first challenge is build a free standing structure using spaghetti, marshmallow, tape and string.

Type of Structure: Design 1)Mass structures (p ) -Can be made by piling up or forming similar materials into a particular shape or design -Advantages: -Held in place by its own weight -Doesn’t wear down or break easily -Disadvantages: -Uses a lot of materials -Examples: (List as many as you can)

Type of Structure: Design 2) Frame structures (p ) -Advantages: -easy to design and build - use very little materials - can be built quickly -Disadvantages: - might need anchors to the ground - parts have to fit together precisely - might need to be braced or reinforced

Type of Structure: Design 3) Shell structures (p ) -Advantages: - completely empty so make great containers - use very little building material Disadvantages: - flat materials do not easily form shells - careful assembly is required - tiny weaknesses from formation, material, outside forces can easily damage the shell

Type of Structure: Design 4)Mix and Match (p280) - combinations of the strengths of the five different types of structures create super structures - examples: airplanes, hydroelectric dams, geodesic domes, warehouses

Materials and Design What a structure is made out of (materials) and how it is put together (design) can determine its successful function

Materials and Design How do you think you will be able to use paper to make a table strong enough to hold a textbook?

Materials and Design Obtain a sheet of newspaper and tape Roll two pieces of paper into two tight tubes from corner to corner (on the diagonal) and tape it closed Form one rolled paper into a square. Form one rolled paper into a triangle

Materials and Design Push down on each shape. Which one can withstand more force? Does it depend on its orientation? Does it depend on which part of the shape you are applying the force?

Make a Paper Table Build a table, using newspaper (what you take, you must use!) and tape 15 cm high must support at least 1 textbook. Must use a frame structure No countdown timer…

Make a Paper Table When engineers solve a problem, they try different ideas, learn from mistakes and try again. Changing the shape of a material affects its strength. Any shape that distributes the force of a load increases the materials strength (load distribution)

Make a Paper Table Troubleshooting Exit Slip What did you do when the tubes started to unroll? What is load distribution? What did you do when the legs tried to tilt or twist? What did you do when a tube started to buckle? Where did you apply reinforcement in your design? How did your design account for load distribution? What needed to be as sturdy as possible to support the book?

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented A. Paper Church One of the most famous paper tube structures: temporary church building erected after the Great Hanshin earthquake.Great Hanshin earthquake.

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented B. Paper Video Disc - This disc holds more than three times as much data as a standard DVD and is much better for the environment

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented C. Paper House - An engineer built a vacation home out of newspaper into one-inch thick slabs and then used them to make the walls.

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented D. Paper Towels - By mistake, a factory made rolls of paper that were too thick for toilet paper but too weak for most other uses. But where others see problems, engineers see possibilities. The paper was sold as “Sani-Towels” which soon became known as paper towels.

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented E. Paper Batteries - They’re smaller than a postage stamp but can power a light bulb! And they decompose in landfills.

Engineering in Action Check out these items that engineers made out of paper. Then choose from the list and see if you can figure out the year each item was invented F. Paper Dresses - Engineers created paper outfits that were sold in stationary stores where you could get a table cloth to match!

Engineering in Action Paper Church – 1995 Paper Video Disc – 2004 Paper House – 1922 Paper Towels – 1931 Paper Batteries – 2007 Paper Dresses

Function The purpose of the structure May have more than one function Containing Transporting Sheltering Supporting Lifting Fastening Separating Communicating Breaking Holding

Function Aesthetics p284 Beauty in art and nature Colour, symmetry

Function Durability Ability to withstand erosion, weathering, long term repetitive use

Function Safety p285 Margin of safety is the limits of a structure before it fails and hurts someone Balancing Safety with Cost – making structures safe usually are expensive but necessary

Materials The properties or characteristics of the materials must match the purpose of the structure

Materials Composite Materials p286 Composite Made from more than one kind of material that can resist more than one kind of force MDF - Medium-density fibreboard (MDF)

Materials Layered Materials p286 Different materials, pressed and glued together to produce a combination of properties Layers of one substance can be more useful than a single thick piece Can be cost effective and more available

Materials Woven and Knit p287 Hair-like fibres that have been spun (twisted together) into long, thin strings String that can be interlocked into a crisscross pattern Very flexible and stretchable Lightweight, easily transported and stored

Materials Considerations when choosing a material: p Cost Appearance Environmental impact Energy efficiency Availability and waste Function Know your materials

Building Big Experiment with: Building Big*Building Big Shape (as a class) Materials as a chart Materials (test materials – textbook p287 Sneezeproof Strength) Build a TeepeeBuild a Teepee*

Get a whiteboard and …name that joint… Joints p Mobile joints Rigid joints Fasteners Interlocking shapes Ties Adhesives Melting

Name that Joint…

Rigid

Name that Joint…

Adhesive

Name that Joint…

Interlocking Shapes

Name that Joint…

Ties

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Fasteners

Name that Joint…

Melting

Name that Joint…

Mobile