A novel finite element technique is developed for the calculation of the propagation pressure and the state of stress and deformation during buckle propagation in pipelines and tubular structures such as risers and tendons subjected to external pressure. Advantage is taken of the steady-state nature of propagation, permitting an efficient formulation to be implemented within the framework of large displacement/rotation elastoplastic finite element analysis. The relatively low computational requirements allow for a parametric study to be conducted for a range of values of the diameter-to-thickness ratio.
Initially, the problem of buckle propagation is reviewed briefly, and the pertinent equations of continuum, mechanics along with the finite element formulation are summarized. The Maxwell line (ring) method is also studied and extended to include the effect of axial force. Finally, the technique, its implementations, results for X-52 steel pipes and for aluminum 6061-T6 for different values of the diameter-to-thickness ratio (D/t), and a study of 1010 carbon steel pipes with different levels of axial force, are presented. Most of the predicted values of the propagation pressure are within 7% of experimental data.
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