A mixed formulation for stress analysis of curved pipes with tangent terminations under in-plane forces

Curved pipes connected to tangent terminations play an important role in process equipment design for fluid transport. These structures allow changes in flow direction and simultaneously contribute to increasing the flexibility of the entire structure. The stress analysis of curved pipes (or pipe elbows) is an essential step in the design of a piping systems project. The method of hybrid formulation of shell parameters (internal forces and displacements) is an alternative to the irreducible formulation, which deals with a totally assumed displacement field for the unknowns. The main advantage of the proposed method lies in the use of lower order formulations for the differential equations used to set-up the solution as compared with the irreducible formulation. The hybrid solution here is based on a semi-analytic formulation, where the definition of the shell forces and displacements combines analytic and trigonometric functions. Tests for the most common loading cases are analysed and results for stress distribution are discussed.