Hi,
Equivalent stress = (0.5^0.5))*((s1-s2)^2 +(s2-s3)^2 +(s3-s1)^2)^0.5
I am using the above formula to add principle stresses.
CASE 1
If I have a very long tube and want to find the stress in the wall.
I get hoop stress = 100 MPa. (Neglect radial stresses).
Therefore if my material yield...