pub fn poisson_ratio(transverse_strain: f64, axial_strain: f64) -> Option<f64>Expand description
Computes Poisson’s ratio from transverse and axial strain.
Formula: ν = -ε_transverse / ε_axial.
Returns None when axial_strain is zero or when any input or result is not finite.
Auxetic values are allowed; common stable isotropic materials often fall within a narrower
non-negative range.