Safety Assessment Methods For Ship Structures Based On Failure Assessment Diagram

A lot of theoretical research work has been made for the structures’ fracture andplacticity failure of ships and offshore platforms. Therefore, we should let the researchachievements work better in Engineering production design. For the brittle material,elastic fracture theory is used to determine structures’ failure or not. However, For mostplastic material, such as low and intermediate Strength steel, elastic fracture theory can’twork better, and clear plastic zone may be found at the crack tip. Theory of elastic-plasticfracture mechanics can work better this time. And, some structures with cracks will beplastic yielding in large load, in other words, placticity failure be called. So, to find asimple and reasonable method to judge structures with cracks failure or not is veryimportant. Failure assessment diagram(FAD) is very impactful. Its vertical coordinatesdescribes the fracture behavior of structures, and its horizontal ordinate describes theplastic behavior of structures. It works better to combine the structures’ fracture behaviorand plastic behavior and is widely used in petroleum pipe line and pressure vessel respectsto judge structures with defects failure or not in foreign engineering.Virtual crack closure technique(VCCT) and numerical computation method of thereference stress are used in FAD, which realize the numerical computation of FAD. It’s agood method to realize numerical solution of failure assessment diagram after comparingthe numerical solution with the analytical solution for some typical structures of ship.Many efforts has be made to let the FAD play a role in safety assessment methods for shipstructures. And we hope it can be written in interrelated code and standard for China.