Auxetic Hinge Generator
Create auxetic cut patterns made of rotating squares. Short horizontal and vertical slits alternate on a grid; the squares between them hang on narrow ligaments and rotate when stretched — the material expands in both directions when bent and wraps around doubly curved surfaces such as spheres or saddles.
Material
Cut Parameters
Length of each slit – the cell size of the rotating squares follows from it
Distance from a slit end to the neighbouring perpendicular slit – the ligaments the squares hinge on
Effective: cell 7.41 × 7.69 mm, slits 11.81 / 12.38 mm
Appearance
No design generated
What Is an Auxetic Living Hinge?
An auxetic material gets wider when it is stretched instead of narrower. The rotating-squares pattern is the classic way to build this behaviour into a flat sheet: horizontal and vertical slits alternate on a square grid like a checkerboard, and the squares between them are connected only at their corners by short ligaments.
When the sheet is pulled or bent, the squares rotate around those ligaments. Neighbouring squares turn in opposite directions, the slits open into diamonds, and the pattern expands along both axes at once. This is what lets a flat sheet wrap around a sphere, a dome, or a saddle surface without buckling.
Every slit is an open cut whose ends stop one ligament width before the neighbouring perpendicular slits. Cuts never touch, so no closed loop is ever cut into the sheet and every square stays attached to its neighbours. The generator checks all neighbouring slits before it produces output and refuses ligaments below 0.5 mm.
Recommended Settings by Material
| Material | Slit Length | Ligament | Result |
|---|---|---|---|
| 1.5 mm Aircraft Plywood | 8–12 mm | 1–1.5 mm | Wraps tight curves, large stretch |
| 3 mm Plywood | 12–20 mm | 1.5–2.5 mm | Even stretch, sturdy ligaments |
| 3 mm MDF | 15–20 mm | 2–3 mm | Moderate stretch, clean cuts |
| 2 mm Polypropylene | 6–10 mm | 1–2 mm | Very flexible, fatigue resistant |
Tips & Best Practices
Ligaments Carry Everything
The short strips at the square corners take all the movement. Use 1.5–2.5 mm in plywood and 2–3 mm in acrylic; below 1 mm they tear after a few cycles.
Cell Size Sets the Curvature
Shorter slits give smaller squares that follow tight curves; longer slits stretch further but need a larger radius. For spherical surfaces a test cut with two sizes pays off.
Align to Edges
With the edge alignment switched on, whole squares fit the width and the height of the plate. The ligament width stays as set; the slit lengths adapt per direction and are shown below the parameters.
Stretch in Both Directions
Unlike slit hinges, the pattern has no preferred bend axis. Test a small piece by pulling it diagonally—the squares should rotate evenly without any ligament whitening or cracking.
Common Applications
Domes & Spherical Surfaces
Flat material that stretches over spheres, domes, and saddle surfaces—made possible by expansion in both directions.
Wearables
Arm cuffs, masks, and form-fitting accessories that adapt to the body in several directions.
Lampshades
Spherical lamps where the grid opens up when stretched and creates a lively light pattern.
Cushioning & Padding
Flexible inserts and protective surfaces that adapt under pressure instead of kinking.
Frequently Asked Questions
What is an auxetic living hinge?
An auxetic living hinge uses the rotating-squares pattern: short horizontal and vertical slits alternate on a square grid, and the squares between them hang on narrow ligaments at their corners. When the sheet is stretched, the squares rotate and the pattern opens up in both directions at once, so the material can wrap around spheres, domes, and saddle surfaces.
What do slit length and ligament width control?
The slit length sets the cell size: the grid pitch is half the slit length plus the ligament width. The ligament width is the strip of material between a slit end and the neighbouring perpendicular slit; it is the hinge every square rotates on. Shorter slits give smaller cells that wrap tighter around curves, narrower ligaments rotate more easily but tear sooner.
Can the slits ever touch each other?
No. Every slit ends exactly one ligament width before the neighbouring perpendicular slits by construction, and parallel slits are a full cell apart. The generator additionally checks all neighbouring slits and refuses ligaments below 0.5 mm, so no cuts merge and no region of the sheet is ever cut loose.