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> struta pb1' pa1 -1.0 sqr(0.60) 1 Con * <Member> strutc1 pc2' pc1 -1.0 sqr(0.60) 1 Con * <Member> strutc2 pc3' pc2 -1.0 sqr(0.60) 1 Con * <Member> strutc3 pc1' pc3 -1.0 sqr(0.60) 1 Con * # interlayer tendons <Member> xltc1 pc1' pc1 1.0 0.0 3 Obj * <Member> xltc2 pc2' pc2 1.0 0.0 3 Obj * <Member> xltc3 pc3' pc3 1.0 0.0 3 Obj * <Member> xltb1 pb1' pc1 1.0 sqr(0.25) 3 Con * <Member> xltb2 pb1' pc2 1.0 sqr(0.25) 3 Con * <Member> xltb3 pb1' pc3 1.0 sqr(0.25) 3 Con * <Member> xlta1 pa1 pc1 1.0 sqr(0.55) 3 Con * <Member> xlta2 pa1 pc2 1.0 sqr(0.55) 3 Con * <Member> xlta3 pa1 pc3 1.0 sqr(0.55) 3 Con * # end tendons <Member> endc1' pc2' pc1' 1.0 sqr(0.58762079226) 4 Con * <Member> endc2' pc3' pc2' 1.0 sqr(0.58762079226) 4 Con * <Member> endc3' pc1' pc3' 1.0 sqr(0.58762079226) 4 Con *
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 pin insertion point to pin insertion point, as are the tendon lengths. The values are in model units. struta: 0.6 strutc1: 0.6 strutc2: 0.6 strutc3: 0.6 xltc1: 0.301195 xltc2: 0.301195 xltc3: 0.301195 xltb1: 0.25 xltb2: 0.25 xltb3: 0.25 xlta1: 0.55 xlta2: 0.55 xlta3: 0.55 endc1': 0.587621 endc2': 0.587621 endc3': 0.587621
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: -0.641147 strutc1: -0.6 strutc2: -0.6 strutc3: -0.6 xltc1: 0.301195 xltc2: 0.301195 xltc3: 0.301195 xltb1: 0.534289 xltb2: 0.534289 xltb3: 0.534289 xlta1: 0.235087 xlta2: 0.235087 xlta3: 0.235087 endc1': 0.229129 endc2': 0.229129 endc3': 0.229129 Average tendon force magnitude: 0.324925
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 3/16-inch-diameter wooden dowel. The tendons were made of 12-lb.-test braided nylon fishing line. In this case, the attachment point at the hubs was a simple metal pin stuck into the end of the strut, so no member-length adjustments were necessary. Prestress forces are assumed not to affect strut lengths. Elongation of Tendon of Unit Cross Section Under Force of Average Magnitude (fraction)> .02 Length Scale Factor> 100/0.6 Strut and Tendon Hub Adjustments - s;t> 0 0 struta: 100 0 strutc1: 100 0 strutc2: 100 0 strutc3: 100 0 xltc1: 49 1 xltc2: 49 1 xltc3: 49 1 xltb1: 40 1 xltb2: 40 1 xltb3: 40 1 xlta1: 90 1 xlta2: 90 1 xlta3: 90 1 endc1': 96 1 endc2': 96 1 endc3': 96 1
Aspension Skylon II with Point Labels
structure file: marcus/x3l2marcuse.rc variable file: marcus/x3l2marcuse.dat digit list: src/mm.dls |
CONTACT: Bob Burkhardt Tensegrity Solutions Box 426164 Cambridge, MA 02142-0021 USA e-mail: bobwb@juno.com |