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. # 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 LengthsThese 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: 108.451835367679Relative Member Force MagnitudesThese 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: 39.2833293907693Construction 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 |

CONTACT:

Bob Burkhardt

Tensegrity Solutions

Box 426164

Cambridge, MA 02142-0021

USA

e-mail: bobwb@juno.com