Effects of creep properties of materials on unified creep constraint parameter A_c for cracked pipes

ABSTRACT

Extensive finite element analyses of cracked pipes with different crack sizes and orientations have been conducted to investigate effects of creep properties of materials on the unified creep constraint parameter A_c. The results show that the constraint parameter A_c is independent on Norton’s coefficient A, and it is only affected by the creep exponent n of materials. For a given crack size, with increasing n, A_c decreases and constraint level increases. The A_c of lower constraint cracks is more sensitive to n. The unified correlation equations between A_c and n have been obtained for cracked pipes with a wide range of crack sizes and constraint levels. They may be used to estimate the constraint parameter A_c at different positions along the crack fronts in cracked pipes made of materials with different n values. The two-parameter C*-A_c approach for assessing creep life of cracked pipes has also been discussed.

KEYWORDS:

• Creep
• constraint parameter A_c
• creep exponent
• cracked pipe
• material
• crack

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was financially supported by the National Key Research and Development Program of China (2018YFC080880) and the Projects of the National Natural Science Foundation of China (51575184 and 51835003) and the Fundamental Research Funds for the Central Universities (50321071918005) .