Notice that in the example of Chapter 7.1, the shear stress increased in magnitude while the normal stresses decreased. The opposite can occur as well; you can rotate the element in such a way to reduce the shear stress and “contribute” it to the normal stresses.
What if we wanted to “contribute” all shear stress to the normal stresses? The result will be maximum normal stresses, or what we call principal stresses.
Similarly we can rotate the element in such a way to get the maximum shear stress or τmax in-plane. In this case we get average stresses for the normal stress instead (you’ll see why in Mohr’s Circle).
Here are the formulas for you to get principal σ and τmax in-plane:
Notice that in the example of Chapter 7.1, the shear stress increased in magnitude while the normal stresses decreased. The opposite can occur as well; you can rotate the element in such a way to reduce the shear stress and “contribute” it to the normal stresses.
What if we wanted to “contribute” all shear stress to the normal stresses? The result will be maximum normal stresses, or what we call principal stresses.
Similarly we can rotate the element in such a way to get the maximum shear stress or τmax in-plane. In this case we get average stresses for the normal stress instead (you’ll see why in Mohr’s Circle).
Here are the formulas for you to get principal σ and τmax in-plane:
