are positive in tension and shear stresses 
are positive when they tend to produce counterclockwise rotation of the material
Angle 
is between the x-axis and the normal to the section
b.)These equations are valid for any material, whether it behaves linearly or nonlinearly, elastically or inelastically.
a) Maximum Normal and Shear Stresses
i) The maximum normal Stress occurs at 
and is 
ii) 
and the largest negative value when 
