LAUSR

Abstract Based on extensive three-dimensional finite element analyses and the unified creep constraint parameter Ac, systematic studies have been carried out to examine effects of a wide range of dimensions of test specimens (C(T), SEN(T) and M(T)) on creep crack-tip constraint. The parameter Ac solutions for the test specimens also have been obtained and are tabulated. It has been shown that the thickness B/W of the test specimens has the most significant effect on creep constraint, and the second is effect of the specimen width W. With increasing B/W and W, the constraint levels of specimens increase. The effect of crack depth a/W on creep constraint is not obvious. The comparison and matching of creep constraint between the standard test specimens recommended in ASTM-E1457 and non-standard specimens and pipes with a wide range of axial and circumferential crack sizes have been investigated. The results obtained are suitable for wider materials and may be used to choose constraint designed test specimens in creep life assessments of pipes with different crack size ranges, and to avoid non-conservative assessments for deeper and longer pipe cracks.