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. # strutsstruta po2' pi1 -1.0 0.0 1 Obj CalcClear * strutb pi1' po2 -1.0 0.0 1 Obj CalcClear * # interlayer tendons xlta pi1' po1 0.0 sqr(2.0) 3 Con CalcClear * xltb pi1 po1' 0.0 sqr(2.0) 3 Con CalcClear * # end tendons end pi2 pi1 0.0 1.0 2 Con CalcClear * end' pi2' pi1' 0.0 1.0 4 Con CalcClear * endx pi1 po2 0.0 1.0 2 Con CalcClear * endx' po2' pi1' 0.0 1.0 4 Con CalcClear * 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. struta: 2.64575 strutb: 2.64575 xlta: 2 xltb: 2 end: 1 end': 1 endx: 1 endx': 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. struta: -2.64575 strutb: -2.64575 xlta: 2 xltb: 2 end: 2 end': 2 endx: 1 endx': 1 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. The tendons were made of braided nylon fishing line. Prestress forces were assumed not to affect strut lengths. Elongation of Tendon of Unit Cross Section Under Force of Average Magnitude (fraction)> .02 Length Scale Factor> 170/2.64575 Strut and Tendon Hub Adjustments - s;t> 6.0 3.5 (The 6.0 mm adjustment for the strut is the amount the screw-eye center extends from the dowel. The 3.5 mm adjustment for the tendon is half the outer diameter of the screw eye.) struta: 158 0 strutb: 158 0 xlta: 118 1 xltb: 118 1 end: 56 0 end': 56 0 endx: 56 1 endx': 56 1
View of Variation on Emmerich's Prism
with Point Labels
structure file: tprism/x3eaprism2.rc variable file: tprism/x3eaprism2.dat digit list: src/mm.dls |
CONTACT:
Bob Burkhardt
Tensegrity Solutions
Box 426164
Cambridge, MA 02142-0021
USA
e-mail: bobwb@juno.com