V-Expander


Read here about the V-expander. It refers to the use of a v-shaped rigid strut in a tensegrity structure.

The V-expander is an example of non-linear strut. For our purposes, it is a form of a nucleated strut. For more information on strut morphology see Strut, Strut, Curved, Strut, Ring.

V-Expander as a Module in a Grid


Motro defined the V-Expander in "Tensegrity: structural systems for the future" as follows. The V expander is constituted by two struts, each one converging to a pin jointed node, placed respectively on either grid's flexible layer. The expander's axis, joining this couple of nodes, is normal to the layer's surface. an active cable materializes the expander's axis. By reducing its length, it is tensioned and introduces a pre-stress (self-stress) state.

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v-expander rendering from "Tensegrity" by Motro fig 7.6 page 194


Vinicius Raducanu, who worked on the Tensarch Project at Montpellier, applied this “V-expander” to different geometries: bi-, tri- and quadri-directional tensegrity grids.

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4 v-expander, published as Bi-dimensional double-layer grid Laboratoire de Mécanique et Génie Civil by Montpellier. Illustration by Gómez-Jáuregui



Tensegrity V-Expander as the basis for a Helix


Robert Mathieson recently posted to his website helixes composed of v-expander modules. He wrote, "the v-expander module is constructed from four equal length compressive members, six equal length outer tension cables and a central tendon. The center tendon is crucial as it stresses the whole structure, holds the form together and gives it rigidity."

Below, 1 v-expander module by Mathieson.

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1 v expander module by Mathieson

Below, a helix composed of repeating v-expander modules.

V-Expander_Helix_by_Mathieson_top.jpg
V-Expander Helix by Mathieson



Portal To Basic Concepts
A series of pages addressing critical concepts; see also the index.

Tensegrity> Benefits, Chronology, Definitions, Dynamics, Force, Geodesic Dome, Humor, Mast, Nexorade, Prestress, Pneumatics, prestress, Stability, Stiffness, Stress, Videos
Compression> Strut: Curved, Linear, Nucleated, Ring, Spring
Tension> Floating, Tendon, Membrane, Wire Roap, Materials

Forms> Bicycle wheel, Buckminsterfullerene, Folding, Musical instruments, Plane, Prism, Skew, Specific Strength, Springs, Torus, Tuning, Wall, Weaving
Materials> Bone, DNA, Fabric, Glass, Inox, Integrin, Spring, Tendon Materials, Wire Roap
Founders> Fuller, Snelson