Theoretical and numerical analysis of end force of multilayer bellows expansion joint

Multilayer bellows expansion joint is a thin-walled shell widely used in underground pipeline systems for displacement compensation and vibration absorbing. The bellows expansion joint's end force affects the underground pipeline's safety. It is urgent to solve the end force of the bellows expansion joint theoretically. However, scholars only obtained the coupling solution of the end force of the bellows expansion joint, which is inconvenient in theoretical analysis and engineering application. This paper proposes a decoupling solution for a bellows expansion joint based on theoretical and numerical methods. The end force is decoupled to the deviation of the bending pressure which is caused by overcoming its own stiffness and internal pressure. In the end force expression, stiffness and internal pressure are independent of each other, which can evaluate the influence of asymmetric pressure difference and external load on end force more accurately. In the end, the accuracy of the decoupling solution is verified by the finite element method and coupling solution. The results show that the decoupling solution agrees with the results obtained by the finite element method and coupling solution. It can provide a theoretical basis for the design of the bellows structure.