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Concentric Five-fold Prisms 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> strut1 p2' p1   0.0      sqr(2.40147) 1 Con CalcClear Inelastic *
<Member> strut2 p4' p5  -1.0      0.0          1 Obj CalcClear Inelastic *

# side tendon
<Member> side1  p4' p1'  0.0      sqr(1.0) 3 Con *
<Member> side2  p4  p4'  0.0      sqr(1.0) 3 Con *
<Member> side3  p1  p4   0.0      sqr(1.0) 3 Con *

# end tendons
<Member> end1   p2  p1   0.0      sqr(1.0) 2 Con *
<Member> end2   p2' p1'  0.0      sqr(1.0) 4 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
        screw-eye center to screw-eye center, as are the tendon lengths.
        These values are in model units.

   strut1:      2.40147    strut2:      2.40147     side1:            1
    side2:            1     side3:            1      end1:            1
     end2:            1


        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.

   strut1:     -1.39986    strut2:     -2.40147     side1:      1.90028
    side2:      2.50822     side3:      1.90028      end1:      1.40999
     end2:      1.40999


        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> 212/2.40147
        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.)

   strut1: 198 0    strut2: 198 0     side1:  78 1     side2:  78 0
    side3:  78 1      end1:  79 0      end2:  79 0

ray trace of concentric five-fold prisms
Concentric Five-fold Prisms with Point Labels

structure file:  tprism/x5girdle2.rc
variable file:   tprism/x5girdle2.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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