Thursday, January 20, 2011

Construct your own Dome

Heres a fun and challenging project I found that I've tried out, and even though it took a really long time, it was fun and worth it in the end. Try it out for yourselves! 

Geodesic domes are made of interconnected triangles that approximate the shape of a sphere. This project shows you how to build a geodesic dome using rolled-up newspapers and tape. How much weight do you think your dome will support? Build one and find out!

The goal of this project is to build a geodesic dome using struts made from rolled-up newspaper. You will determine the strength-to-weight ratio of the resulting dome.

Intro image
A geodesic dome is a structure made of interconnected struts that approximate the shape of a sphere (or hemisphere). The struts are joined together in triangles, with the vertices of the triangles designed to fall approximately on the sphere. The struts form a rigid network that transmits stress forces throughout the structure. The sides of the triangles form great circles (geodesics) over the surface of the sphere. (Wikipedia contributors, 2006a)
Geodesic domes have some very interesting properties. Since the structure approximates a sphere, geodesic domes have very high surface-to-volume ratios. In fact, geodesic domes enclose more volume per unit weight than any other man-made structure made from linear elements. They are also the only known man-made structure that increases in strength as the size of the structure is increased. (Wikipedia contributors, 2006a)
While you are doing your background research for this project, you should spend some time reading about Richard Buckminster Fuller, who named, patented, and popularized geodesic domes. He had a lot of interesting ideas for maximizing efficiency in design, trying to do "more with less."
In this project, you will build a geodesic dome using tubes made from rolled-up newspaper, taped together.

  • How much weight do you think your dome will be able to support?
Materials and Equipment
To do this experiment you will need the following materials and equipment:
  • many newspapers,
  • masking tape,
  • measuring tape,
  • markers,
  • many magazines (for strength testing),
  • optional: glitter, beads, and glue for decorating.
Experimental Procedure
  1. Stack three flat sheets of newspaper together. Starting in one corner, roll the sheets up together as tightly as you can to form a tube. When you reach the other corner, tape the tube to keep it from unrolling. Repeat until you have 65 tubes.

    Illustration of how to roll the newspapers, starting from one corner.
  2. Now cut down the tubes to make 35 "longs" and 30 "shorts."
    1. Longs: Cut off both ends of a tube until it is 71 centimeters long. Use this tube as a model to create 34 more longs. Be sure to mark all the longs clearly in some way, such as with colored marker at each end, so you can tell them apart from the shorts. Decorate the tubes if you like.
    2. Shorts: Cut off both ends of another tube until it is 66 cm long. Use this tube as a model to create 29 more shorts. Decorate the tubes if you like.

    Illustration of rolled, taped and trimmed paper tubes for use in constructing a large geodesic dome.
  3. First, tape 10 longs together to make the base of the dome.

    Illustration of base of dome, using 10 long tubes.
  4. Tape a long and a short to each joint. Arrange them so that there are two longs next to each other, followed by two shorts, and so on, as shown below.

    Illustration of straws ring with long and short pieces attached at vertices.
  5. Tape the tops of two adjacent shorts together to make a triangle. Tape the next two longs together, and so on all the way around.

    Illustration of ring of straws, with long and short pieces attached to form bracing triangles.
  6. Connect the tops of these new triangles with a row of shorts. The dome will start curving inward.

    Illustration of straws ring with second tier ring attached to top of bracing triangles.
  7. At each joint where four shorts come together, tape another short sticking straight up. Connect this short to the joints on either side with longs, forming new triangles.

    Illustration of straws ring with next tier of bracing longs and shorts.
  8. Connect the tops of these new triangles with a row of longs.

    Illustration of straws ring with next level of bracing.
  9. Finally, add the last five shorts so that they meet at a single point in the center of the dome. You might need to stand inside the dome to tape them together.

    Illustration of completed straws construction.
  1. How much does the dome weigh?
  2. How strong is it? To test your dome's strength, see how many magazines you can load on top. Adult supervision is recommended for this step. Add magazines gradually. Observe the dome carefully for signs of impending failure.
  3. What was the strength-to-weight ratio of the dome?
  4. Did the results surprise you? Why or why not?
  5. What was the hardest part about creating the dome?
  • What part of the dome failed during strength testing? How could you strengthen this part (or parts)? Would different materials or a different method of fastening the parts together make the dome stronger? Try your proposed solution and see if it works.
  • How could you make your dome stronger without interrupting the space underneath it? Make a prediction and test it.
  • Can you use the same materials to make another structure, with a different shape, that is as strong as the geodesic dome? What shape did you choose for your structure? How much does it weigh? How strong is it? What is its strength-to-weight ratio? How do these measurements compare to those that you made for the geodesic dome?
  • For a much more advanced project, you could try designing your own geodesic dome. The Bibliography lists several references to help you get started (Anderson, 1998a; Anderson, 1998b; Kenner, 2003; Landry, 2002).
Edited by Andrew Olson, Ph.D., Science Buddies
This project idea, including the experimental procedure and construction images, is from:

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