A failure assessment diagram (FAD) approach is strongly expected to be useful for the simplified fracture assessment. The applicability of FAD approach to ductile fracture strength analysis was verified using a heavy section 9%Ni steel plate and its weld joints, in use for large scale LNG storage tank, in this paper. Various ductile fracture tests using compact and center cracked panel specimens were carried out in order to observe stable crack extension behavior and to estimate failure strength.
The obtained results are summarized as follows :
(1) When the assessment by means of Option 2 FADs is considered, an appropriate failure assessment curve (FAC) which takes account of actual fracture behavior should be selected.
(2) The accuracy of assessment by FAD approach was strongly affected by the precision of estimation of limit load for Lr.
(3) In case of 9%Ni steel, stable crack behavior agreed well with FAC regardless the specimen thickness.
(4) Maximum load measured in experiments and its prediction by FAD were in good agreement regardless the specimen configuration. In case of 9%Ni weld joints, however, FAD approach showed a poor accuracy in the ductile tearing analysis and the maximum load prediction.
