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Triangularly Girdled Six-fold Prism Datasheet


Copyright © 2004 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> strut1a    p01   p09    0.00   sqr(2.1)   1 Con CalcClear *
<Member> strut1b    p02   p07    0.00   sqr(2.1)   1 Con CalcClear *
<Member> strut2     p11   p12    0.00   sqr(2.1)   1 Con CalcClear *

# hexagon tendon
<Member> hexten1a   p01   p02    0.00   sqr(1.0)   2 Con *
<Member> hexten1b   p02   p03    0.00   sqr(1.0)   2 Con *
<Member> hexten2a   p07   p08    0.00   sqr(1.0)   2 Con *
<Member> hexten2b   p07   p09    0.00   sqr(1.0)   2 Con *

# side tendons
<Member> side1a     p02   p11    1.00   0.0        3 Obj *
<Member> side1b     p03   p12    0.00   sqr(1.221805837)   3 Con *
<Member> side2a     p09   p11    0.00   sqr(1.221805837)   2 Con *
<Member> side2b     p07   p12    1.00   0.0        2 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
        screw-eye center to screw-eye center, as are the tendon lengths.
        These values are in model units.

  strut1a:          2.1   strut1b:          2.1    strut2:          2.1
 hexten1a:            1  hexten1b:            1  hexten2a:            1
 hexten2b:            1    side1a:     0.652903    side1b:      1.22181
   side2a:      1.22181    side2b:     0.652903


        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.

  strut1a:     -1.10881   strut1b:    -0.800146    strut2:     -1.02511
 hexten1a:     0.478954  hexten1b:     0.902131  hexten2a:     0.478954
 hexten2b:     0.902131    side1a:     0.652903    side1b:      1.04223
   side2a:      1.04223    side2b:     0.652903


        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 5/16-inch-diameter wooden dowel.
        Braided nylon fishing line was used for the tendons.
        Prestress forces are assumed to affect tendon lengths and
        not strut lengths.

        Elongation of Tendon of Unit Cross Section
        Under Force of Average Magnitude (fraction)> 0.02
        Length Scale Factor> 212/2.1
        Strut and Tendon Hub Adjustments - s;t> 7.0 4.0
        (The 7.0 mm adjustment for the strut is the amount
         the screw-eye center extends from the dowel.  The 4.0 mm
	 adjustment for the tendon is half the outer diameter of the
         screw eye.)

  strut1a: 198 0   strut1b: 198 0    strut2: 198 0  hexten1a:  92 0
 hexten1b:  91 0  hexten2a:  92 0  hexten2b:  91 0    side1a:  57 0
   side1b: 112 1    side2a: 112 1    side2b:  57 0

ray trace of triangularly girdled six-fold prism
Triangularly Girdled Six-fold Tensegrity Prism
with Point Labels
(VRML Model)

structure file:  tprism/x6girdle1.rc
variable file:   tprism/x6girdle1.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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