Schmid's Law

Schmid's Law (also Schmid factor, m) describes the slip plane and the slip direction of a stressed material, which can resolve the most amount of shear stress.

Schmid's Law states that the critically resolved shear stress (τ) is equal to the stress applied to the material (σ) multiplied by the cosine of the angle with the glide plane (Φ) and the cosine of the angle with the glide direction (λ). Which can be expressed as: