FLEXIBLE STRUCTURES

1 . A flexible structure comprising a plurality of interlinked spring units, each spring unit comprising at least three coaxial coiled springs, wherein each spring of a spring unit comprises a first end and second end, and wherein an end of one spring adjoins an end of a spring of an adjacent spring unit.

2 . The flexible structure of claim 1 , wherein the spring units are waisted.

3 . The flexible structure of claim 1 , comprising four coaxial coiled springs.

4 . The flexible structure of claim 1 , wherein each spring unit comprises an integer number of springs, and, for spring units which are not at an edge of the fabric, each spring is connected to at least the same integer number of springs of other spring units.

5 . The flexible structure of claim 1 , which is formed by additive manufacturing.

6 . The flexible structure of claim 1 in which each spring unit has a height, width and depth dimension of less than 1 cm.

7 . The flexible structure of claim 1 in which each spring comprises a coiled wire-like element of less than 1 mm, and wherein the springs of are separated from one another with a clearance of less than 1 mm.

8 . A flexible fabric formed by additive manufacturing, the fabric comprising a plurality of adjoining spring units,

each spring unit comprising at least three spiral spring elements extending from a lower end to an upper end around a central axis,

wherein the upper end of a first spring element of a first spring unit is continuously formed with the upper end of a spring element of a second spring unit, and the lower end of the first spring element is continuously formed with the lower end of a spring element of a third spring unit.

9 . The flexible fabric of claim 8 , wherein the spring units are arranged in a regular grid.

10 . A method comprising:

determining, by processing circuitry, an intended property for a flexible structure to be formed by additive manufacturing, the flexible structure comprising a plurality of interlinked spring units, each spring unit comprising at least three coaxial coiled springs formed of spring filaments and the intended property comprising at least one of a volume of the structure and a flexibility of the structure;

determining, by processing circuitry, a geometry of the structure,

determining, by processing circuitry, a physical attribute for the structure based on the intended property, the physical attribute comprising at least one of a size of the spring unit and the diameter of a spring filament; and

determining, by processing circuitry, a flexible structure data model for use in generating the flexible structure having the geometry and the physical attribute in additive manufacturing.

11 . A method according to claim 10 wherein determining the geometry of the structure comprises determining a spring unit geometry, wherein determining a spring unit geometry comprises determining at least one of:

a number of springs in a spring unit;

a spring pitch;

a spring length;

a number of partial turns of a spring; and

a taper angle.

12 . A method according to claim 10 further comprising:

determining an object model for generating an object having a flexible structure incorporated therein, the object model comprising the flexible structure data model.

13 . A method according to claim 12 comprising:

obtaining a first object model comprising a void;

transforming and/or replicating at least one spring unit to provide a geometric shape for the structure which corresponds to the predetermined void;

modifying the first object model to comprise the structure in the region of the void.

14 . A method according to claim 10 further comprising

determining additive manufacturing instructions based on the data model, which when executed by an additive manufacturing apparatus, cause the additive manufacturing apparatus to generate the structure;

wherein determining the additive manufacturing instructions comprises determining the instructions based on a predetermined mapping between the model data and print agents, wherein the predetermined mapping is a mapping for generating flexible structures.

15 . A method according to claim 14 further comprising executing the instructions to generate the object.