Smr2 (Valley material portion)
Smr2 (valley material portion) is the percentage of the measurement area that comprises the deeper valley structures associated with Svk.
Sk represents the height of the core surface, Smr1 represents the areal material ratio that divides the reduced peaks from the core surface, and Smr2 represents the areal material ratio that divides the reduced valleys from the core surface.
The reduced peaks are the areas that are removed by initial abrasion. Spk represents the average height of the reduced peaks.
The reduced valleys are the areas that hold liquid applied on the surface in order to improve lubricity. Svk represents the average depth of the reduced valleys.