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Datasheet for Skew Eight-Prism


Copyright © 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> 01(c) pt01 pt02  0.0 sqr(1.0) 2 Con *
<Member> 02(c) pt02 pt03  0.0 sqr(1.0) 2 Con *
<Member> 03(c) pt03 pt04  0.0 sqr(1.0) 2 Con *
<Member> 04(c) pt04 pt05  0.0 sqr(1.0) 2 Con *
<Member> 05(c) pt05 pt06  0.0 sqr(1.0) 2 Con *
<Member> 06(c) pt06 pt07  0.0 sqr(1.0) 2 Con *
<Member> 07(c) pt07 pt08  0.0 sqr(1.0) 2 Con *
<Member> 08(c) pt08 pt01  0.0 sqr(1.0) 2 Con *
<Member> 09(c) pt01 pt09  1.0 sqr(2.1) 7 Con *
<Member> 10(c) pt02 pt10  1.0 0.0      3 Obj *
<Member> 11(c) pt03 pt11  1.0 0.0      3 Obj *
<Member> 12(c) pt04 pt12  1.0 0.0      3 Obj *
<Member> 13(c) pt05 pt13  1.0 0.0      3 Obj *
<Member> 14(c) pt06 pt14  1.0 0.0      3 Obj *
<Member> 15(c) pt07 pt15  1.0 0.0      3 Obj *
<Member> 16(c) pt08 pt16  1.0 0.0      3 Obj *
<Member> 17(s) pt01 pt16 -1.0 0.0      1 Obj *
<Member> 18(s) pt02 pt09 -1.0 sqr(3.0) 1 Con *
<Member> 19(s) pt03 pt10 -1.0 0.0      1 Obj *
<Member> 20(s) pt04 pt11 -1.0 0.0      1 Obj *
<Member> 21(s) pt05 pt12 -1.0 0.0      1 Obj *
<Member> 22(s) pt06 pt13 -1.0 0.0      1 Obj *
<Member> 23(s) pt07 pt14 -1.0 0.0      1 Obj *
<Member> 24(s) pt08 pt15 -1.0 0.0      1 Obj *
<Member> 25(c) pt09 pt10  0.0 sqr(0.8) 2 Con *
<Member> 26(c) pt10 pt11  0.0 sqr(0.8) 2 Con *
<Member> 27(c) pt11 pt12  0.0 sqr(1.0) 2 Con *
<Member> 28(c) pt12 pt13  0.0 sqr(1.0) 2 Con *
<Member> 29(c) pt13 pt14  0.0 sqr(0.8) 2 Con *
<Member> 30(c) pt14 pt15  0.0 sqr(0.8) 2 Con *
<Member> 31(c) pt15 pt16  0.0 sqr(1.0) 2 Con *
<Member> 32(c) pt16 pt09  0.0 sqr(1.0) 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.

    01(c):            1     02(c):            1     03(c):            1
    04(c):            1     05(c):            1     06(c):            1
    07(c):            1     08(c):            1     09(c):          2.1
    10(c):      2.79295     11(c):      3.12529     12(c):      2.93865
    13(c):       2.2802     14(c):      1.47522     15(c):     0.981849
    16(c):      1.30782     17(s):      2.10244     18(s):            3
    19(s):      3.64012     20(s):      3.81178     21(s):      3.20853
    22(s):      2.12729     23(s):      1.32768     24(s):      1.32601
    25(c):          0.8     26(c):          0.8     27(c):            1
    28(c):            1     29(c):          0.8     30(c):          0.8
    31(c):            1     32(c):            1

        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.

    01(c):      1.18407     02(c):      1.25909     03(c):      1.18407
    04(c):      1.09222     05(c):      1.18407     06(c):      1.25909
    07(c):      1.18407     08(c):      1.09222     09(c):          2.1
    10(c):      2.79295     11(c):      3.12529     12(c):      2.93865
    13(c):       2.2802     14(c):      1.47522     15(c):     0.981849
    16(c):      1.30782     17(s):     -2.10244     18(s):           -3
    19(s):     -3.64012     20(s):     -3.81178     21(s):     -3.20853
    22(s):     -2.12729     23(s):     -1.32768     24(s):     -1.32601
    25(c):      1.22347     26(c):      1.22347     27(c):      1.38094
    28(c):      1.38094     29(c):      1.22347     30(c):      1.22347
    31(c):      1.38094     32(c):      1.38094

        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> 60
        Strut and Tendon Hub Adjustments - s;t> 0 0
 
    01(c):  59 0     02(c):  59 0     03(c):  59 0     04(c):  59 0
    05(c):  59 0     06(c):  59 0     07(c):  59 0     08(c):  59 0
    09(c): 122 1     10(c): 161 1     11(c): 180 0     12(c): 170 0
    13(c): 133 0     14(c):  87 0     15(c):  58 0     16(c):  77 0
    17(s): 126 0     18(s): 180 0     19(s): 218 1     20(s): 228 1
    21(s): 192 1     22(s): 127 1     23(s):  79 1     24(s):  79 1
    25(c):  47 0     26(c):  47 0     27(c):  59 0     28(c):  59 0
    29(c):  47 0     30(c):  47 0     31(c):  59 0     32(c):  59 0


pedagogic view of skew eight-prism
Skew Eight-Prism with Point Labels

structure file:  sk8prsm/stage1.rc
 variable file:  sk8prsm/stage2.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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