Lets build a Geodesic Dome!
Introduce students to the geodesic dome but do not define it yet. The next 4 slides have pictures of domes, well show these and ask the students what these structures have in common, noting that all structures are geodesic domes. Then we will ask students what they think a geodesic dome is based on the pictures, then we will give them a definition.Mitchell Park: is a conservatory located at Mitchell Park in Milwaukee, Wisconsin, U.S..Superior Dome: opened as the worlds largest wooden dome on September 14, 1991, is a domed stadium on the campus of Northern Michigan University in Marquette, Michigan. Tacoma Dome: is an indoor arena located in Tacoma, Washington, USA and often referred to as "The Woodshed". Completed in 1983 for $44 million and opened on April 21, the arena seats 17,100 for basketball. It is the world's second largest arena with a wooden dome (only the Superior Dome in Marquette, MI is larger with a 536 foot diameter), and one of the largest geodesic domes. Geodesic dome home.The Project Eden: is a large-scale environmental complex near St. Austell, Cornwall, England, United Kingdom. The biomes are constructed from a tubular steel frame with mostly hexagonal transparent panels (there are a few pentagonal ones) made from the complex plastic ETFE (it was decided very early on that glass was out of the question, being too heavy and potentially dangerous). The "panes" of the biome are created from a triple layer of thin UV-transparent ETFE film, inflated to create a large space between the two sides and trapping heat like double-glazed windows. The plastic is resistant to most stains, which simply wipe off in the rain, although if required, cleaning is performed by abseilers (similar to window cleaners). Although the plastic is prone to punctures, these can be fixed with ETFE tape. The structure is completely self-supporting, with no internal supports, and takes the form of a geodesic structure. The panels vary in size up to 9 m across, with the largest at the top of the structure.Geodesic dome green house.On this slide we define a geodesic come. Geodesic domes are mostly made out of triangles but they can also be made from other triangular shapes. The Project Eden domes are made from hexagons and pentagons, these are considered triangular shapes because the the triangles connect at a point.The different parts of the shapes under go two different forces, tension and compression.This slide goes along with an activity. Using pins and straws create a square and a triangle. The straws are the beams and the pins hold the beams together at the joints. We will have the students apply pressure to the top of the square and the triangle but before they do ask them what they think will happen. Will the shapes deform, if so how?
This slide shows how the force from the hand (black arrow) is distributed throughout the shapes (red arrow). This picture shows what is happening to the shapes when under stress.This picture shows how the force from the hand distributed throughout the shape. Notice how not all beams experience compression or tension, even thought the overall force is a downward force. Some beams are stretched while others undergo compression. Notice that even some beams undergo both tension and compression.When a structure is under stress (tension or compression) it might undergo strain. In this activity the square undergoes strain and can deform in several ways. The triangle, however, retains its shape. Thus the triangle is a better structure.This slide introduces the concept of a load bearing structure. In the picture above, ask the students which pillar they think is a load bearing structure. Ask them what they think would happen if you removed one of the pillars? What about removing two of the pillars?
After the students build and test their geo-desic dome ask them which beams they think are most important. Are there any they could remove and have the structure remain standing?Now that students know what a geodesic dome is and how it behaves they can begin building their own!