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. <Member> end1 pt1A pt1B 0.0 sqr(2.95572) 3 Con * <Member> st13p pt1A pt3a 0.0 sqr(2.43699) 1 Con CalcClear * <Member> st13q pt1B pt3b 0.0 sqr(2.43699) 1 Con CalcClear * <Member> side1ap pt1A pt3b 1.0 0.0 3 Obj * <Member> side1cp pt1A pt2B 1.0 0.0 3 Obj * <Member> side1aq pt1B pt3a 1.0 0.0 3 Obj * <Member> side1cq pt1B pt2A 1.0 0.0 3 Obj * <Member> gird1ap pt2A pt3a 0.0 sqr(1.0) 2 Con * <Member> gird1bp pt2A pt3b 0.0 sqr(1.0) 2 Con * <Member> gird1aq pt2B pt3b 0.0 sqr(1.0) 2 Con * <Member> gird1bq pt2B pt3a 0.0 sqr(1.0) 2 Con * <Member> st24p pt2A pt4a 0.0 sqr(2.43699) 1 Con CalcClear * <Member> st24q pt2B pt4b 0.0 sqr(2.43699) 1 Con CalcClear * <Member> side2ap pt2A pt4b 1.0 0.0 3 Obj * <Member> side2bp pt4a pt3a 1.0 0.0 3 Obj * <Member> side2aq pt2B pt4a 1.0 0.0 3 Obj * <Member> side2bq pt4b pt3b 1.0 0.0 3 Obj * <Member> end2 pt4b pt4a 0.0 sqr(2.95572) 3 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. end1: 2.95572 st13p: 2.43699 st13q: 2.43699 side1ap: 1.47679 side1cp: 1.66364 side1aq: 1.47679 side1cq: 1.66364 gird1ap: 1 gird1bp: 1 gird1aq: 1 gird1bq: 1 st24p: 2.43699 st24q: 2.43699 side2ap: 1.47679 side2bp: 1.66364 side2aq: 1.47679 side2bq: 1.66364 end2: 2.95572
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. end1: 1.61982 st13p: -4.27662 st13q: -4.27662 side1ap: 1.47679 side1cp: 1.66364 side1aq: 1.47679 side1cq: 1.66364 gird1ap: 3.07959 gird1bp: 3.07959 gird1aq: 3.07959 gird1bq: 3.07959 st24p: -4.27662 st24q: -4.27662 side2ap: 1.47679 side2bp: 1.66364 side2aq: 1.47679 side2bq: 1.66364 end2: 1.61982 Average tendon force magnitude: 2.00855
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 1/4-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 5 mm o.d. (size 217½) screw eye in the end of the strut. 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> 208/2.43699 Strut and Tendon Hub Adjustments - s;t> 4, 2.5 end1: 243 1 st13p: 200 0 st13q: 200 0 side1ap: 119 1 side1cp: 135 0 side1aq: 119 1 side1cq: 135 0 gird1ap: 78 0 gird1bp: 78 0 gird1aq: 78 0 gird1bq: 78 0 st24p: 200 0 st24q: 200 0 side2ap: 119 1 side2bp: 135 0 side2aq: 119 1 side2bq: 135 0 end2: 243 1
Construction Lengths II (in millimeters and halves) The construction length for the strut now represents the length of a 3/16-inch-diameter wooden dowel. The tendons continue to be made of 12-lb.-test braided nylon fishing line, but now the attachment point at the hubs is a small nail stuck into the end of the strut, so no member-length adjustments were necessary. Elongation of Tendon of Unit Cross Section Under Force of Average Magnitude (fraction)> .02 Length Scale Factor> 150/2.43699 Strut and Tendon Hub Adjustments - s;t> 0, 0 end1: 179 0 st13p: 150 0 st13q: 150 0 side1ap: 89 1 side1cp: 100 1 side1aq: 89 1 side1cq: 100 1 gird1ap: 59 1 gird1bp: 59 1 gird1aq: 59 1 gird1bq: 59 1 st24p: 150 0 st24q: 150 0 side2ap: 89 1 side2bp: 100 1 side2aq: 89 1 side2bq: 100 1 end2: 179 0
X-Module Tetrahedron with Point Labels
structure file: chain/x2l2chain5.rc variable file: chain/x2l2chain5.dat digit list: src/mm.dls |
CONTACT: Bob Burkhardt Tensegrity Solutions Box 426164 Cambridge, MA 02142-0021 USA e-mail: bobwb@juno.com |