pub fn axial_stiffness(
area: f64,
youngs_modulus: f64,
length: f64,
) -> Option<f64>Expand description
Computes axial stiffness of a uniform elastic bar.
Formula: k = AE / L.
Returns None when area is negative, youngs_modulus is negative, length is less than or
equal to zero, or when any input or result is not finite.