What is this?
“Pretenst” structure, otherwise known as tensegrity, is structure which is distilled down to the basics of push and pull, making all of the forces visible. It is minimal, and as a result these structures appear to defy gravity, and that gives them their elegant beauty.
The defining feature of tensegrity is that the pushing elements or bars are floating, separated from each other and only held together by a network of tension. The shape maintains its integrity because of the tension, with or without gravity, since the compression pushing outwards is only localized.
This project has two parts. It is both about a piece of open source software, and about projects to build real world tensegrity structures.
Pretenst software is an open source online tool for designing four-dimensional physical structures made from elements of pure compression (struts) and tension (cables) and exploring how they behave over time and under stress.
The app generates tensegrities based on a minimal language called “tenscript”. For example, the structure called “Halo by Crane” was generated with this short script:
With all the numbers from the generated virtual model, it became possible to build the real physical object!
Scripts have also been written for importing structures into Blender for generating high resolution renderings.
The articles below record the progression of projects and technique refinements which seem to be a necessary part of the journey to really understand this structural principle.
Anything is possible in the virtual world, and although the behavior is convincing and accurate to seven digits, it completely sidesteps the details of the connection mechanism, and the imperfections of real world materials. Building physical pretenst objects exposes us to the realities of tension and compression.
One fairly unique feature of our approach here is that the tension network is almost always assembled in a slack state and only tightened later. High tension is achieved purely by effectively lengthening the compression elements instead.
It is this approach which enabled the building of complex tensegrity structures, and primarily because it becomes possible to return the structure to a slack state temporarily for repairs or adjustments.
Pretenst Constructions:2021-04-08: "Bow Tie Tensegrity": better bend resistance
2021-03-29: "Six Twist Essential": what if more hands could see?!
2021-01-25: "Minimal Tensegrity": no more tension lines than absolutely necessary
2021-01-18: "Degrees of Freedom": first adjustable hybrid tensegrity
2021-01-11: "Fractal Experiment": a tensegrity of tensegrities
2020-12-09: "Axial Tension": pretensing what is already pretenst
2020-11-02: "Halo by Crane - Part 2": the strengthening
2020-10-26: "Halo by Crane - Part 1": assembly complete but strength lacking
2020-10-12: "Brass and Tulips": a tight and strong tensegrity tower
2020-08-10: "Prefab Tension Tower": the tower of eight twists
2020-07-27: "Elastic Bubble": building with elastic ease
2020-07-13: "The Twist Sisters": left-handed and right-handed
2020-07-06: "Radial Tension": Pulling towards the middle
2020-06-22: "Diamond of Tension": Four pulls for every push
2020-06-15: "Prefab Tension": Separating compression from tension
Software:2021-03-10: "Do the Twist": constructing in push-pull space
2021-03-01: "Elastic Interval Geometry": pure pairwise push and pull