Fabric Elastic Constants On axis

Warp Modulus (E1) MPa

Fill Modulus (E2) MPa

In-Plane Shear Modulus (G12) MPa

Poisson's Ratio (v12)

Load Case On the diagonal

Applied Bias Stress MPa

Panel Length on the Bias m

Bias Modulus at 45°

— MPa

Off-axis stiffness from the orthotropic transformation

Diagonal Behaviour

Bias Strain: — %
Panel Elongation: — mm
Strain if Loaded Along Warp: — %
Warp Stiffness over Bias Stiffness: — ×
Shear Share of Bias Compliance: — %

Linear elastic and small-strain: a real sail on the bias also scissors its yarn crossings, which is strongly non-linear and not captured here. Use this to compare constructions and to see where the compliance sits, then confirm on a biaxial or picture-frame test before committing a sail plan.

Sailcloth Bias Stretch & Modulus Calculator — free, with the formula and a worked example, at Textile School.