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Datasheet for Four-fold Aspension Skylon


Copyright © 2008 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> struta      pb1' pa1  -1.0      sqr(0.612372435695794)  1 Con *
<Member> strutc1     pc2' pc1  -1.0      sqr(0.612372435695794)  1 Con *
<Member> strutc2     pc3' pc2  -1.0      sqr(0.612372435695794)  1 Con *
<Member> strutc3     pc4' pc3  -1.0      sqr(0.612372435695794)  1 Con *
<Member> strutc4     pc1' pc4  -1.0      sqr(0.612372435695794)  1 Con *

# interlayer tendons
<Member> xltc1       pc1' pc1   1.0      0.0        3 Obj *
<Member> xltc2       pc2' pc2   1.0      0.0        3 Obj *
<Member> xltc3       pc3' pc3   1.0      0.0        3 Obj *
<Member> xltc4       pc4' pc4   1.0      0.0        3 Obj *
<Member> xltb1       pb1' pc1   1.0      sqr(0.281508125152624)  3 Con *
<Member> xltb2       pb1' pc2   1.0      sqr(0.281508125152624)  3 Con *
<Member> xltb3       pb1' pc3   1.0      sqr(0.281508125152624)  3 Con *
<Member> xltb4       pb1' pc4   1.0      sqr(0.281508125152624)  3 Con *
<Member> xlta1       pa1  pc1   1.0      sqr(0.543831936790269)  3 Con *
<Member> xlta2       pa1  pc2   1.0      sqr(0.543831936790269)  3 Con *
<Member> xlta3       pa1  pc3   1.0      sqr(0.543831936790269)  3 Con *
<Member> xlta4       pa1  pc4   1.0      sqr(0.543831936790269)  3 Con *

# end tendons
<Member> endc1'      pc2' pc1'  1.0      sqr(0.50)  4 Con *
<Member> endc2'      pc3' pc2'  1.0      sqr(0.50)  4 Con *
<Member> endc3'      pc4' pc3'  1.0      sqr(0.50)  4 Con *
<Member> endc4'      pc1' pc4'  1.0      sqr(0.50)  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 pin insertion
        point to pin insertion point, as are the tendon lengths.
        The values are in model units.

   struta:     0.612372   strutc1:     0.612372   strutc2:     0.612372
  strutc3:     0.612372   strutc4:     0.612372     xltc1:     0.353553
    xltc2:     0.353553     xltc3:     0.353553     xltc4:     0.353553
    xltb1:     0.281508     xltb2:     0.281508     xltb3:     0.281508
    xltb4:     0.281508     xlta1:     0.543832     xlta2:     0.543832
    xlta3:     0.543832     xlta4:     0.543832    endc1':          0.5
   endc2':          0.5    endc3':          0.5    endc4':          0.5

        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.

   struta:    -0.816497   strutc1:    -0.612372   strutc2:    -0.612372
  strutc3:    -0.612372   strutc4:    -0.612372     xltc1:     0.353553
    xltc2:     0.353553     xltc3:     0.353553     xltc4:     0.353553
    xltb1:     0.444037     xltb2:     0.444037     xltb3:     0.444037
    xltb4:     0.444037     xlta1:      0.22985     xlta2:      0.22985
    xlta3:      0.22985     xlta4:      0.22985    endc1':         0.25
   endc2':         0.25    endc3':         0.25    endc4':         0.25

        Average tendon force magnitude: 0.31936

        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 15-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> 177/0.612372435695794
        Strut and Tendon Hub Adjustments - s;t> 0 0

   struta: 177 0   strutc1: 177 0   strutc2: 177 0   strutc3: 177 0
  strutc4: 177 0     xltc1: 100 0     xltc2: 100 0     xltc3: 100 0
    xltc4: 100 0     xltb1:  79 0     xltb2:  79 0     xltb3:  79 0
    xltb4:  79 0     xlta1: 155 0     xlta2: 155 0     xlta3: 155 0
    xlta4: 155 0    endc1': 142 1    endc2': 142 1    endc3': 142 1
   endc4': 142 1

pedagogic view of aspension skylon
Four-fold Aspension Skylon with Point Labels

structure file:  marcus/x4l2marcuse.rc
 variable file:  marcus/x4l2marcuse.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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