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> s1 c1 p1 -1.00 sqr(170) 1 Con CalcClear *
<Member> s2 c1 p2 -1.00 sqr(170) 1 Con CalcClear *
<Member> s3 c2 p3 -1.00 sqr(170) 1 Con CalcClear *
<Member> s4 c2 p4 -1.00 sqr(170) 1 Con CalcClear *
# tendons
<Member> t1-2 p1 p2 1.00 sqr(216.903670735357) 3 Con *
<Member> t1-3 p1 p3 1.00 sqr(216.903670735357) 2 Con *
<Member> t1-4 p1 p4 1.00 sqr(216.903670735357) 2 Con *
<Member> t2-3 p2 p3 1.00 sqr(216.903670735357) 2 Con *
<Member> t2-4 p2 p4 1.00 sqr(216.903670735357) 2 Con *
<Member> t3-4 p3 p4 1.00 sqr(216.903670735357) 3 Con *
<Member> tc c1 c2 1.00 sqr(108.451835367679) 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
screw-eye center to screw-eye center, as are the tendon lengths.
The values are in model units.
s1: 170 s2: 170
s3: 170 s4: 170
t1-2: 216.903670735357 t1-3: 216.903670735357
t1-4: 216.903670735357 t2-3: 216.903670735357
t2-4: 216.903670735357 t3-4: 216.903670735357
tc: 108.451835367679
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.
s1: -70.4163056034263 s2: -70.4163056034263
s3: -70.4163056034265 s4: -70.4163056034261
t1-2: 6.57870696324024 t1-3: 38.3435141103065
t1-4: 38.3435141103062 t2-3: 38.3435141103065
t2-4: 38.3435141103063 t3-4: 6.57870696324026
tc: 108.451835367679
Average tendon force magnitude: 39.2833293907693
Construction Lengths (in mm 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 a member
represents the distance between the locations where it
departs from the hubs. The struts are cut from
5/16-inch diameter hardwood dowel. The tendons are made
of single strands of braided nylon fishing line except
for member tc where two strands are used.
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)> .02
Length Scale Factor> 1
Strut and Tendon Hub Adjustments - s;t> 7 3.5
(subtract 2*(7 mm) off strut lengths to get dowel lengths;
subtract 2*(3.5 mm) off tendon lengths to get hub-adjusted
in-situ tendon lengths)
s1: 156 0 s2: 156 0 s3: 156 0 s4: 156 0
t1-2: 209 0 t1-3: 206 0 t1-4: 206 0 t2-3: 206 0
t2-4: 206 0 t3-4: 209 0 tc: 98 1

Tensegrity Tetrahedron Point Labels
structure file: tetra/tetra4.rc
variable file: tetra/tetra4.dat
cross-section table: tetra/tetra4.cst
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CONTACT:
Bob Burkhardt
Tensegrity Solutions
Box 426164
Cambridge, MA 02142-0021
USA
e-mail: bobwb@juno.com