FITNET FFS Methodologies for the Assessment of Low Constraint Conditions: Overview, Contents and New Contributions

In the last years constraint has represented one of the major issues on fracture mechanics and structural integrity research. The need of more adjusted less conservative (and still safe) assessments requires, in many cases, the consideration of the constraint conditions in the crack tip in order to make better predictions of the load bearing capacity or the critical crack dimensions. The newly developed FITNET FFS Procedure gathers a comprehensive set of methodologies for the assessment of low constraint conditions, from those ones that have their origin on the crack shallowness and/or the type of loading (something that is also treated in other procedures), to those related to the notch effect (included for first time in an assessment procedure). Moreover, one of the biggest difficulties that has been traditionally found when performing constraint assessments, has been the obtainment of the different material and constraint parameters that have to be implemented in the calculations. FITNET FFS has dedicated special efforts in providing values of these parameters for a wide variety of materials and geometries, so that the application of its constraint assessment methodologies is noticeably simplified if compared to other procedures. This paper presents these FITNET FFS constraint methodologies and the advances achieved by the procedure in the constraint field.