Effective Modulus for Crack Size Measurement With SE(T) Specimens using Unloading Compliance

摘要

Low-constraint toughness tests have been increasingly used in pipeline flaw assessment. A number of protocols have been published using a test employing a clamped single-edge tension (SE(T)) specimen with the distance between the clamps H equal to ten times the specimen width W, and specimen width Unequal to thickness 6. For this geometry, the constraint over the bulk of the specimen varies between plane stress and plane strain. This affects the elastic compliance, commonly used to estimate crack size. It was the intent of the present work to assess the effects of constraint on the compliance and to identify the best combination of compliance equation and modulus to estimate crack size from CMOD compliance where CMOD is the crack mouth opening displacement. To do this, values of compliance from finite element analyses were provided by the authors of this paper from three separate laboratories. 2D plane strain, 3D plane-sided, and 3D side-grooved specimens were analyzed. The data were used to assess available compliance equations and to propose a new one for the specific geometry of interest in this work.