The Flexibility of Curved Pipes in Creep

The redistribution of stress in a linear, thin shell model of a curved pipe creeping under the action of a constant applied in-plane bending moment is represented by an equation of evolution in time. Using finite differences, this continuous system is reduced to a finite set of initial value problems which are numerically integrated using a fifth order Runge-Kutta method. The flexibility of the curved pipe is compared to that of a similar elastic, and a similarly creeping, straight pipe. Results are compared with two simple approximate methods and with a previous-steady state analysis.