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> strut1a p01 p09 0.00 sqr(2.1) 1 Con CalcClear * <Member> strut1b p02 p07 0.00 sqr(2.1) 1 Con CalcClear * <Member> strut2 p11 p12 0.00 sqr(2.1) 1 Con CalcClear * # hexagon tendon <Member> hexten1a p01 p02 0.00 sqr(1.0) 2 Con * <Member> hexten1b p02 p03 0.00 sqr(1.0) 2 Con * <Member> hexten2a p07 p08 0.00 sqr(1.0) 2 Con * <Member> hexten2b p07 p09 0.00 sqr(1.0) 2 Con * # side tendons <Member> side1a p02 p11 1.00 0.0 3 Obj * <Member> side1b p03 p12 0.00 sqr(1.221805837) 3 Con * <Member> side2a p09 p11 0.00 sqr(1.221805837) 2 Con * <Member> side2b p07 p12 1.00 0.0 2 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. These values are in model units. strut1a: 2.1 strut1b: 2.1 strut2: 2.1 hexten1a: 1 hexten1b: 1 hexten2a: 1 hexten2b: 1 side1a: 0.652903 side1b: 1.22181 side2a: 1.22181 side2b: 0.652903 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. strut1a: -1.10881 strut1b: -0.800146 strut2: -1.02511 hexten1a: 0.478954 hexten1b: 0.902131 hexten2a: 0.478954 hexten2b: 0.902131 side1a: 0.652903 side1b: 1.04223 side2a: 1.04223 side2b: 0.652903 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 5/16-inch-diameter wooden dowel. Braided nylon fishing line was used for the tendons. 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)> 0.02 Length Scale Factor> 212/2.1 Strut and Tendon Hub Adjustments - s;t> 7.0 4.0 (The 7.0 mm adjustment for the strut is the amount the screw-eye center extends from the dowel. The 4.0 mm adjustment for the tendon is half the outer diameter of the screw eye.) strut1a: 198 0 strut1b: 198 0 strut2: 198 0 hexten1a: 92 0 hexten1b: 91 0 hexten2a: 92 0 hexten2b: 91 0 side1a: 57 0 side1b: 112 1 side2a: 112 1 side2b: 57 0
Triangularly Girdled Six-fold Tensegrity Prism
with Point Labels
(VRML Model)
structure file: tprism/x6girdle1.rc variable file: tprism/x6girdle1.dat digit list: src/mm.dls |
CONTACT:
Bob Burkhardt
Tensegrity Solutions
Box 426164
Cambridge, MA 02142-0021
USA
e-mail: bobwb@juno.com