<P> Critical resolved shear stress (CRSS) is the component of shear stress, resolved in the direction of slip, necessary to initiate slip in a grain . Resolved shear stress (RSS) is the shear component of an applied tensile or compressive stress resolved along a slip plane that is other than perpendicular or parallel to the stress axis . The RSS is related to the applied stress by a geometrical factor, m, typically the Schmid factor: </P> <P> τ RSS = σ app m = σ app (cos ⁡ φ cos ⁡ λ) (\ displaystyle \ tau _ (\ text (RSS)) = \ sigma _ (\ text (app)) m = \ sigma _ (\ text (app)) (\ cos \ phi \ cos \ lambda)) </P> <P> where σ is the magnitude of the applied tensile stress, Φ is the angle between the normal of the slip plane and the direction of the applied force, and λ is the angle between the slip direction and the direction of the applied force . The Schmid Factor is most applicable to FCC single crystal metals, but for polycrystal metals the Taylor factor has been shown to be more accurate . The CRSS is the value of resolved shear stress at which yielding of the grain occurs, marking the onset of plastic deformation . CRSS, therefore, is a material property and is not dependent on the applied load or grain orientation . The CRSS is related to the observed yield strength of the material by the maximum value of the Schmid factor: </P> <P> σ y = τ CRSS m max (\ displaystyle \ sigma _ (y) = (\ frac (\ tau _ (\ text (CRSS))) (m_ (\ text (max))))) </P>

What is critical resolved shear stress derive its formula