Accuracy of a measuring instrument is expressed as

A machined surface with standard symbols indicating the surface texture is shown in the Figure. (ALL dimensions in the Figure are in micrometer).

The waviness height (in micrometer) of the surface is

If $$E$$ is the modulus of elasticity in $$GPa$$, $$G$$ is the shear modulus in $$GPa$$ and $$v$$ is the Poisson's ratio of a linear elastic and isotropic material, the three terms are related as

For a two dimensional state-of-stress defined as $${\sigma _{xx}} = {\sigma _{yy}} = {\tau _{xy}} = S,$$ the Mohr's circle of stress has