Combined-stress analysis at a point subjected to multiple simultaneous loading actions (internal pressure, axial force, bending, torsion, shear) proceeds by computing the normal and shear stress contribution of each individual load resultant, algebraically superposing them to obtain resultant Sigma-x, Sigma-y, and Tau-xy at that point, and then applying Mohr's circle or stress-transformation equations to determine the principal stresses and maximum shear stress. For thin-walled pressure vessels specifically, internal pressure produces circumferential (hoop) and longitudinal normal stresses that superpose with normal stress from an external axial load and shear stress from an applied torque, and points on the neutral axis under combined bending and torsion experience pure shear (zero normal stress) since bending stress vanishes there.
Combined-stress analysis at a point subjected to multiple simultaneous loading actions (internal pressure, axial force, bending, torsion, shear) proceeds by computing the normal and shear stress cont…