Presentation on theme: ""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."— Presentation transcript:
"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 Structure Workshop Welcome to an IncreDIble Illinois Structure Workshop Please check in! 12:30- 1:00 p.m. Brainstorming: One idea per Post it®:
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.
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. 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
Intro to teaching basic structure Wood Jigs Forces Glue Tools and More Tools Construction Area This years 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.
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)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?
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 Structure Column Brace Member Stress / (Forces)
Stress (Forces) that act on a structure 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
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
BalsaBalsa Estimate Weight Balsa Actual Weight Weight Held Estimate Weight Held Actual 36XX 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
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-ack- relate") 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 Carpenters wood glue (Elmers) –Factors to consider Strength Drying time Weight Ease of use Provide Adequate Ventilation !
Airplane Glue Gorilla Glue Glass Surface to build on Wood Glues CA Super Glues Acetone Extra CA Glue Tips Old Razor - to clean glass Pill bottles to clean CA Glue Tips Glues Contact Cement
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 No Horseplay Read and Follow Safety Instructions If you cant use it safely – dont use it Dont 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 small aluminum mitre box for razor saw Other useful building items: Flat tile or mirror Building square Emery boards, sand paper All tools should be readily available to consumers and of the teams own choosing
Level/Straight Edge Levels are usually used to see if a surface is perfectly level (meaning it wont 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
Clear Plastic Ruler comes in handy when youre 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 youve measured it, be sure to measure it again. There is an old woodworking saying Measure twice, cut once. Thats because it is a lot easier to fix a mistake before you make it than afterwards. Woodworking Basics Measuring Tools
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 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.
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
Sample materials that can be used to make templates Aluminum Square Tube from hardware store Plastic and brass square tube from Hobby store Steel keystock from hardware store 1x1 from lumber yard
This Years 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
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 bystructure The Presser Board & weights are fully supported by structure
Tester setup Team Designed Structures Floor surface Metal Weights Traditional Tester Supporting Blocks Pressure Board 7.5 to 9 2 nd structure inside first structure Top of red tape is 1 below top of pole
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! 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 first- time 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 dont have to make snap decisions at tournament that they might regret.
Your team will: 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.
Weight Placement 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 Dont change too many variables between tests Dont change too many things at once
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 Good structures look good Keep it simple Keep in Level Keep it Well-glued Have Fun!
Acknowledgements Victor TomBill Allen Pre-engineering Corp (pictures) 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