Summary
The development of an efficient analytical procedure for the determination of the propagation pressure is the goal of this work. The previous studies of Tassoulas and his associated (Katsounas and Tassoulas, 1989; Song and Tassoulas, 1990) serve as foundations of which this work is built.
The original contribution of this work is the treatment of the propagating buckle as a steady-state. This approach permits the development of an algorithm that gives precise results with significantly reduced computational effort.
The contents of this work are organized in the following way:
Task 1: Experimental and analytical models for the determination of the propagation pressure, which were developed in previous work, are described. Their results are assessed. Not all models are reviewed here (for this is not a historical compendium);
Only the more widely accepted and most rationally developed. These models are experimental results will serve as a basis for comparison of this work.
Task 2: The tensors and equations of Continuum Mechanics, relevant to the present work, are reviewed. Although this material can be found in a number of textbooks, it is included for completeness and for the reader’s convenience in following the fundamental relationships used or in attempting to reproduce the results.
Task 3: The nine-node isoparametric shell element (degenerated brick), adapted to nonlinear analysis, is described. A special feature of the element –namely, the pressure node—necessary to track unstable equilibrium paths is also discussed.
Task 4: The Finite Element formulation is used to analyze rings under external pressure and axial tension. A simplified method to determine the propagation pressure is implemented and the results are compared to experiments and other models.
Task 5: The propagating buckle problem is formulated as an instability of a steady-state nature in a three-dimensional continuum. Parameters that determine the quality of the solution are studied.
Task 6: Parametric studies using the method described in Tasks are presented for pipes under pressure and axial force. Comparisons with experimental results are performed.
Task 7: Conclusions and recommendations for further research are presented.
Related Publications: Nogueira, A.C. and Tassoulas, J.L., “Steady-State Analysis of Buckle Propagation,” Proceedings, ASCE Structures Congress XII, Atlanta, Georgia, April 24-28, 1994, Vol. 2, pp. 1514-1519.
Nogueira, A.C. and Tassoulas, J.L., “Buckle Propagation: Steady-State Finite Element Analysis,” Journal of Engineering Mechanics, American Society of Civil Engineers, Vol. 120, No. 9, pp. 1931-1944, September 1994.
Nogueira, A.C. and Tassoulas, J.L., “Buckle Propagation in Tubular Structures,” Paper No. 7803, Proceedings, Offshore Technology Conference, Houston, Texas, May 1-4, 1995.
Nogueira, A.C. and Tassoulas, J.L., “Finite Element Analysis of Buckle Propagation in Pipelines Under Tension,” International Journal of Mechanical Sciences, Vol. 37, No. 3, pp. 249-259, 1995.
