| In this paper, the C(t) and C* integrals, stress redistribution time tred and creep crack-tip stress distributions in the CT, SENB, SENT and CCT specimens and in axially and circumferential surface cracked pipes have been calculated by the FEM, the creep crack-tip constraint induced by the loading configuration has been investigated, and its correlation to crack-tip constraint in internal-pressure pipelines. The main concluations obtained are as follows:(1) The creep constraint induced by the loading configuration could be characterized and analyzed by the new constraint parameter R. The specimen order in terms of crack-tip constraint (r<0.65mm) from high to low is CT, SENB, SENT and CCT. It can be deduced from the crack-tip constraint that the specimen order in terms of the CCG rate from high to low is CT, SENB, SENT and CCT. This analysis result is consistent with the experimental results in literature.(2) With increasing C* the constraint decreases in the specimens with different loading configurations. At the crack-tip region of 0.1 mm |
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