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Tensegrity Bean Teepee Construction Data


Copyright © 1999, 2005 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.

<Member> strut0608 pt06A pt08a 0.0 sqr(2.5) 1 Con CalcClear Inelastic *
<Member> strut0709 pt07A pt09c 0.0 sqr(2.5) 1 Con CalcClear Inelastic *
<Member> strut0810 pt08A pt10a 0.0 sqr(2.5) 1 Con CalcClear Inelastic *

<Member> baset  pt06A pt06B 0.0 sqr(2.0) 10 Con *
<Member> apext  pt10a pt10b 0.0 sqr(0.5) 10 Con *

<Member> guy0   pt06A pt07B 0.55 0.0      3 Obj *
<Member> guy6   pt06A pt08b 0.35 0.0      3 Obj *
<Member> guy7   pt07A pt09b 0.40 0.0      3 Obj *
<Member> guy8   pt08A pt10b 0.70 0.0      3 Obj *

<Member> xtr8   pt08a pt08A 0.36 0.0      7 Obj *

<Member> TL0607   pt06A pt07A 0.25 0.0      4 Obj *
<Member> TS0708   pt07A pt08a 1.45 0.0      2 Obj *
<Member> TL0708   pt07A pt08B 0.55 0.0      4 Obj *
<Member> tS0708   pt07A pt08b 1.45 0.0      2 Obj *
<Member> TS0809   pt08A pt09b 1.45 0.0      2 Obj *
<Member> tS0809   pt08A pt09a 1.45 0.0      2 Obj *
<Member> tL0809   pt08c pt09a 0.55 0.0      4 Obj *
<Member> tL0910   pt09a pt10a 0.55 0.0      4 Obj *


        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
        hub center to hub center, as are the tendon lengths.
        These values are in model units.

strut0608:          2.5 strut0709:          2.5 strut0810:          2.5
    baset:            2     apext:          0.5      guy0:      1.06079
     guy6:      1.76225      guy7:      2.16525      guy8:      2.39895
     xtr8:     0.855865    TL0607:      1.82586    TS0708:     0.940875
   TL0708:      1.61585    tS0708:      1.09291    TS0809:     0.957033
   tS0809:     0.851856    tL0809:      1.68392    tL0910:      1.80869


        Relative Member Prestress 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.

strut0608:     -2.06741 strut0709:     -3.22737 strut0810:     -2.72331
    baset:     0.467791     apext:     0.424326      guy0:     0.583432
     guy6:     0.616788      guy7:     0.866101      guy8:      1.67927
     xtr8:     0.308111    TL0607:     0.456466    TS0708:      1.36427
   TL0708:     0.888719    tS0708:      1.58471    TS0809:       1.3877
   tS0809:      1.23519    tL0809:     0.926157    tL0910:     0.994779

        Average tendon force magnitude: 0.918921


        Construction Lengths (in inches, 16ths and 32nds)
        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 a member
        represents the distance between the locations where it
        departs from the hub.  The struts were cut from
        1-inch by 1-inch hardwood garden stakes.  The tendon material
        was single strands of twisted #18 nylon twine.  Its behavior
        under stress is highly non-linear, so a look-up table
        was used to compute strains.  Prestress forces were assumed
        to affect tendon lengths and not strut lengths.

        Average Tendon Force Magnitude (chart units)> 20
        Length Scale Factor> 42/2.5
        Strut and Tendon Hub Adjustments> 0 0.5
        (adjust the tendon lengths by subtracting a half inch from
         both ends)

strut0608:  42  0 0 strut0709:  42  0 0 strut0810:  42  0 0    baset:  30 13 1 
    apext:   7  0 1      guy0:  15 12 0      guy6:  26 11 0     guy7:  32  7 1 
     guy8:  34  9 1      xtr8:  12 13 1    TL0607:  28  1 1   TS0708:  13  3 1 
   TL0708:  23 15 1    tS0708:  15  5 1    TS0809:  13  7 0   tS0809:  11 15 1 
   tL0809:  24 15 1    tL0910:  26 12 0 

        Base chord length = (2/2.5)*42" = 33.6" = 33 9 1


        Material Quantities
        This provides an estimate of how much material will
        be needed to assemble the structure, in this case
        inches of garden stake and inches of nylon twine.
        The lengths must be adjusted to take into account the
        fact that the strut extends past the hub and some length
        of tendon is required to tie it to the strut.
        The Quantity value given for each Type does not take
        into account the Cross Section value.  The total
        Quantity given across from Tndns does.

        Length Scale Factor> 42/2.5 
        Strut and Tendon Adjustments> 0 (-6)

                    Cross
         Type     Section    Quantity Count

            1           1         378     9
           10           1     187.536     6
            3           1      509.07    12
            7           1       76.03     3
            4           1     417.702    12
            2           1     301.048    12
        Strts                     378     9
        Tndns                 1491.39    45
side view of the tensegrity bean teepee another side view of the tensegrity bean teepee
Two Views of the Tensegrity Bean Teepee
(VRML Model)

Schematic for the Tensegrity Bean Teepee
Schematic for the Tensegrity Bean Teepee

          structure file:  obelisk2/stage4.rc
           variable file:  obelisk2/stage4.dat
stress-strain chart file:  v04oct_d/wellingtn.ssc
         digit list file:  src/standard.dls

CONTACT:

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

e-mail: bobwb@juno.com

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