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Datasheet for First Wheel Based on Gůmez JŠuregui Module


Copyright © 2007 by Bob Burkhardt

        Member Descriptions
        [name, end point names, weight (if in objective function),
        second power of length (if a constraint), member category,
        Obj/Con/Exc (put in objective function, use as a constraint or
        exclude from computations), flags]
        For assembly purposes, only the name and end point names are
        of interest.  The other information may be of interest after
        A Practical Guide to Tensegrity Design has been consulted.

# struts
<Member> sA1F2  A1  F2  -1.000000  sqr(13.3932)   1 Obj CalcClear *
<Member> sB1D2  B1  D2  -1.000000  sqr(13.3932)   1 Obj CalcClear *
<Member> sC1E2  C1  E2  -0.438373  sqr(15.4987)   1 Obj CalcClear *

# tendons
<Member> tA1D1  A1  D1   2.0 sqr(1.50000)  2 Con *
<Member> tA1D2  A1  D2   1.0 sqr(5.50000)  3 Con *
<Member> tA1E1  A1  E1   1.0 sqr(7.06508)  2 Con *
<Member> tB1E1  B1  E1   1.0 sqr(2.00000)  2 Con *
<Member> tB1F1  B1  F1   1.0 sqr(7.06000)  2 Con *
<Member> tC1C2  C1  C2   1.0 sqr(11.0000)  2 Con *
<Member> tC1D1  C1  D1   1.0 sqr(7.06508)  2 Con *
<Member> tC1F1  C1  F1   1.0 sqr(2.00000)  2 Con *
<Member> tE1E2  E1  E2   1.0 sqr(11.0000)  2 Con *

        In-Situ Member Lengths
        These are the lengths of the members when they are in place
        and prestress is applied.  The strut lengths are from pin insertion
        point to pin insertion point, as are the tendon lengths.
        The values are in model units.

    sA1F2:      12.7527     sB1D2:      12.7527     sC1E2:      12.7527
    tA1D1:          1.5     tA1D2:          5.5     tA1E1:      7.06508
    tB1E1:            2     tB1F1:         7.06     tC1C2:           11
    tC1D1:      7.06508     tC1F1:            2     tE1E2:           11

        Relative Member Force Magnitudes
        These values are useful for developing an assembly
        strategy for the structure.  The tighter tendons are much
        easier to tie in place early on, while the looser tendons
        can be left to the last.  This information is also used
        to adjust tendon lengths since the measured length of a tendon
        will be shorter for a highly-stressed tendon with the same
        in-situ length as a tendon which is not so stressed.

    sA1F2:     -12.7527     sB1D2:     -12.7527     sC1E2:     -5.59045
    tA1D1:      5.85918     tA1D2:      9.64597     tA1E1:      6.41162
    tB1E1:      11.6907     tB1F1:      4.57469     tC1C2:      7.50265
    tC1D1:      6.41162     tC1F1:      11.6907     tE1E2:      7.50265

        Average tendon force magnitude: 7.92108

        Construction Lengths (in millimeters and halves)
        The construction length of a tendon is less than the in-situ
        length since when the tendon is measured off it isn't under
        any prestress force.  The construction length for the strut
        represents the length of the 3/16-inch-diameter wooden dowel.
        The tendons were made of 12-lb.-test braided nylon fishing line.
        In this case, the attachment point at the hubs was a simple
        metal pin stuck into the end of the strut, so no member-length
        adjustments were necessary.  Prestress forces are assumed
        not to affect strut lengths.

        Elongation of Tendon of Unit Cross Section
        Under Force of Average Magnitude (fraction)> .02
        Length Scale Factor> 150/12.7527
        Strut and Tendon Hub Adjustments - s;t> 0 0
 
    sA1F2: 150 0     sB1D2: 150 0     sC1E2: 150 0     tA1D1:  17 1
    tA1D2:  63 0     tA1E1:  82 0     tB1E1:  23 0     tB1F1:  82 0
    tC1C2: 127 0     tC1D1:  82 0     tC1F1:  23 0     tE1E2: 127 0


pedagogic view of first wheel based on Gůmez JŠuregui module
First Wheel Based on Gůmez JŠuregui Module with Point Labels

structure file:  val/bridge1a.rc
 variable file:  val/bridge1a.dat
    digit list:  src/mm.dls

CONTACT:

Bob Burkhardt
Tensegrity Solutions
Box 426164
Cambridge, MA 02142-0021
USA

e-mail: bobwb@juno.com

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