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> strut0305 pt03A pt05c 0.0 sqr(2.5) 1 Con CalcClear Inelastic *
<Member> strut0406 pt04A pt06a 0.0 sqr(2.5) 1 Con CalcClear Inelastic *
<Member> strut0507 pt05A pt07c 0.0 sqr(2.5) 1 Con CalcClear Inelastic *
<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 pt03A pt03B 0.0 sqr(1.5) 10 Exc *
<Member> apext pt10a pt10b 0.0 sqr(1.0) 10 Con *
<Member> guy0 pt03A pt04A 0.26 0.0 3 Obj *
<Member> guy3 pt03A pt05b 0.46 0.0 3 Obj *
<Member> guy4 pt04A pt06b 0.37 0.0 3 Obj *
<Member> guy5 pt05A pt07b 0.40 0.0 3 Obj *
<Member> guy6 pt06A pt08b 0.50 0.0 3 Obj *
<Member> guy7 pt07A pt09b 0.45 0.0 3 Obj *
<Member> guy8 pt08A pt10b 0.70 0.0 3 Obj *
<Member> xtr5 pt05a pt05A 0.36 0.0 7 Obj *
<Member> xtr6 pt06a pt06A 0.36 0.0 7 Obj *
<Member> xtr7 pt07a pt07A 0.36 0.0 7 Obj *
<Member> xtr8 pt08a pt08A 0.36 0.0 7 Obj *
<Member> TL0304 pt03A pt04B 0.55 0.0 4 Obj *
<Member> TS0405 pt04A pt05a 1.45 0.0 2 Obj *
<Member> TL0405 pt04A pt05B 0.55 sqr(1.60584) 4 Con *
<Member> tS0405 pt04A pt05b 1.45 0.0 2 Obj *
<Member> TS0506 pt05A pt06a 1.45 sqr(.984101) 2 Con *
<Member> TL0506 pt05A pt06B 0.55 0.0 4 Obj *
<Member> tS0506 pt05A pt06b 1.45 0.0 2 Obj *
<Member> tL0506 pt05a pt06a 0.55 0.0 4 Obj *
<Member> TS0607 pt06A pt07a 1.45 0.0 2 Obj *
<Member> TL0607 pt06A pt07A 0.55 0.0 4 Obj *
<Member> tS0607 pt06A pt07b 1.45 0.0 2 Obj *
<Member> tL0607 pt06a pt07b 0.55 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> tL0708 pt07a pt08a 0.55 0.0 4 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.
strut0305: 2.5 strut0406: 2.5 strut0507: 2.5
strut0608: 2.5 strut0709: 2.5 strut0810: 2.5
baset: 1.51987 apext: 1 guy0: 1.33158
guy3: 2.01281 guy4: 2.18526 guy5: 2.08293
guy6: 2.1659 guy7: 2.22818 guy8: 2.24252
xtr5: 0.8186 xtr6: 0.708883 xtr7: 0.719252
xtr8: 0.805133 TL0304: 1.66303 TS0405: 1.04135
TL0405: 1.60584 tS0405: 0.956123 TS0506: 0.984101
TL0506: 1.60423 tS0506: 1.02919 tL0506: 1.66715
TS0607: 0.994281 TL0607: 1.60176 tS0607: 1.03325
tL0607: 1.61019 TS0708: 1.01978 TL0708: 1.68087
tS0708: 0.984525 tL0708: 1.6565 TS0809: 0.9407
tS0809: 0.907978 tL0809: 1.65306 tL0910: 1.72719
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.
strut0305: -2.43384 strut0406: -2.4833 strut0507: -3.14895
strut0608: -3.3746 strut0709: -3.31851 strut0810: -2.70319
apext: 0.506916 guy0: 0.346211 guy3: 0.925894
guy4: 0.808545 guy5: 0.833171 guy6: 1.08295
guy7: 1.00268 guy8: 1.56976 xtr5: 0.294696
xtr6: 0.255198 xtr7: 0.258931 xtr8: 0.289848
TL0304: 0.914668 TS0405: 1.50996 TL0405: 0.288695
tS0405: 1.38638 TS0506: 0.947462 TL0506: 0.882328
tS0506: 1.49233 tL0506: 0.916934 TS0607: 1.44171
TL0607: 0.880968 tS0607: 1.49822 tL0607: 0.885604
TS0708: 1.47868 TL0708: 0.92448 tS0708: 1.42756
tL0708: 0.911076 TS0809: 1.36402 tS0809: 1.31657
tL0809: 0.90918 tL0910: 0.949954
Average tendon force magnitude: 0.953174
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)
strut0305: 42 0 0 strut0406: 42 0 0 strut0507: 42 0 0 strut0608: 42 0 0
strut0709: 42 0 0 strut0810: 42 0 0 apext: 14 14 1 guy0: 20 7 1
guy3: 30 1 0 guy4: 33 0 0 guy5: 31 5 1 guy6: 32 2 1
guy7: 33 3 1 guy8: 32 8 0 xtr5: 12 4 1 xtr6: 10 8 1
xtr7: 10 11 1 xtr8: 12 1 0 TL0304: 24 11 1 TS0405: 14 10 1
TL0405: 25 0 1 tS0405: 13 7 1 TS0506: 14 3 1 TL0506: 23 13 1
tS0506: 14 8 0 tL0506: 24 12 1 TS0607: 14 0 0 TL0607: 23 13 0
tS0607: 14 8 1 tL0607: 23 15 0 TS0708: 14 5 1 TL0708: 24 15 1
tS0708: 13 14 0 tL0708: 24 10 0 TS0809: 13 4 0 tS0809: 12 12 1
tL0809: 24 9 0 tL0910: 25 10 0
Base chord length = (1.51987/2.5)*42" = 25.5338" = 25 8 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 1 756 18
10 1 81.5565 3
3 1 888.924 21
7 1 287.309 12
4 1 1097.36 30
2 1 767.801 30
Strts 756 18
Tndns 3122.95 96
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Schematic for the Second Tensegrity Obelisk
structure file: obelisk2/stage3.rc
variable file: obelisk2/stage3.dat
stress-strain chart file: v04oct_d/wellingtn.ssc
digit list file: src/standard.dls
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CONTACT:
Bob Burkhardt
Tensegrity Solutions
Box 426164
Cambridge, MA 02142-0021
USA
e-mail: bobwb@juno.com