A child's wagon: I-Beams or Rectangular Tubes?
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Re: A child's wagon: I-Beams or Rectangular Tubes?
Re: A child's wagon: I-Beams or Rectangular Tubes? -- godavesec	Post Reply	Top of thread	Forum

Posted by: daves ® 10/31/2003, 23:46:56 Author Profile Mail author Edit

The factor you are looking for is called "I", the moment of inertia. The following is greatly simplified, but so is your case. Don't use in people-supporting equipment without a thorough background. See:To calculate a tube, just subtract the inside "I" from the outside "I". Generally, the farther apart the average top and bottom materials are from each other the less the material needed. In some cases the web or tube wall that joins the top and bottom material can be very thin. This can lead to the case where the web or wall will wrinkle and allow the top and bottom to come closer - buckling failure. For weight I-beams are usually best - It's why I-beams are so popular in construction. If the web is divided in 2 and pushed to the sides to form a tube, it is half the web thickness and more susceptible to damage which leads to buckling. On the other hand, if there is any twisting, the tube is much more resistant to such deflections -like 10 times or more for similar amounts of material (been 20 years since I've calculated that, so please don't gripe if I'm off a little)

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