General Conclusions
Normal and shear stresses in the x and y directions can be determined by some means for a component.
At orientations other than the x and y directions, there are different combinations of normal stress and shear stress. The x and y stresses don't change — only our reference frame changes.
In one particular orientation, we find the largest normal stresses. These stresses are called principal stresses. On principal stress planes, there is no shear stress.
