It is well known that both the yield strength and the tensile strength of a material have significant effect on the failure behavior of pipelines. Thus it can be anticipated that the yield-to-tensile strength (Y/T) is closely related to the strain hardening behavior of the material, and it also influences the failure behavior. This paper theoretically explores the influence of T/Y (the inverse of Y/T) ratio on the failure pressure of pipelines with or without corrosion defects. Based on the instability of deformation and finite strain theory, a plastic collapse criterion for close-ended pipes without corrosion defects is developed first. The constitutive behavior of line pipes is characterized by a power-law strain hardening relation, while the plastic deformation obeys the Mises yield criterion and the associated deformation theory of plasticity. An approximate relationship between the T/Y ratio and the strain hardening exponent n is obtained, and a closed-form solution to the limit pressure of pipe based on T/Y is derived. This plastic instability model is extended to predict the failure pressure of pipelines with corrosion defects, and validated by the PCRI experimental database. The results show that (a) the T/Y ratio is simply proportional to the strain hardening exponent n, which is almost independent of the yield strain and affected by the definition of the yield stress; (b) the failure pressure predicted by the present plastic instability model increases as the T/Y ratio decreases; and (c) as T/Y → 1, the present solution approaches to that predicted by the Mises strength criterion based on the nominal hoop and axial stresses.
- Pressure Vessels and Piping Division
Influence of the Yield-to-Tensile Strength Ratio on the Failure Assessment of Corroded Pipelines
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Zhu, X, & Leis, BN. "Influence of the Yield-to-Tensile Strength Ratio on the Failure Assessment of Corroded Pipelines." Proceedings of the ASME 2003 Pressure Vessels and Piping Conference. Application of Fracture Mechanics in Failure Assessment. Cleveland, Ohio, USA. July 20–24, 2003. pp. 23-30. ASME. https://doi.org/10.1115/PVP2003-2004
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