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Reply to fifth email from Philip Stewart (second)

Date: Tue, 26 Feb 2002 08:28:00 -0500
From: Bob Burkhardt <>
Subject: Tensegrity stresses

Hi Stu,

Adobe PhotoDeluxe managed to decypher indexer_tube_locator.wmf for me. I plugged the data into my software and was glad to find it thought it was a tensegrity too. Its reading on the relative self-stress forces (doesn't factor in member weights) were:

  (A)-A:     -343.935   (B)-B:     -244.315
  (C)-C:     -74.2161   (D)-D:      -311.55
  (A)-(B):      224.239   (A)-(D):      147.894
    (A)-D:      165.458   (A)-(C):      38.2116
    A-(B):      349.114
      A-B:       78.056     A-(C):      62.1884
      A-C:      58.7093
    (B)-D:      121.684       B-C:      79.0989
      B-D:      145.142
  (C)-(D):      66.3389     C-(D):      215.646
      C-D:      156.821

I wasn't sure what "WL" meant, but it didn't seem to matter. I did a POV rendering ( of the structure to approximately match one of your photos, and it pretty much matches the photo which must mean the gravity related stresses don't distort the structure visibly. I'm beginning to think I should figure out how to compute the gravity component when the structure is completely inelastic which would seem to be a good approximation to your structure. Must be possible if I get time to think about it. If you send me member weights, I'll do what I can. Thanks for sending the data. It was interesting testing my software out on someone else's structure. I'm attaching the POV view I generated along with the POV source files.


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