ELEMENT SIZE DEPENDENT DAMAGE MODELING OF DUCTILE CRACK GROWTH IN CIRCUMFERENTIAL THROUGH-WALL CRACKED PIPE TESTS

This paper proposes an element-size-dependent damage model to simulate ductile crack growth in full-scale cracked pipes. The proposed method is based on the stress-modified fracture strain damage model modified from stress reduction technique proposed previously by the authors. A modification is made that the critical accumulated damage for progressive cracking is assumed to be dependent on the element size. The proposed method is then compared with a circumferential through-wall cracked pipe test that was conducted during Degrade Piping Program[18]. The bending moment at crack initiation, maximum bending moment, crack extension, and J-integral values were calculated from the FE damage analysis. These results were compared with the experimental results. In addition, results obtained from an existing J-estimation scheme were provided for comparison. All results showed reasonable agreement. The results of the present study demonstrate that the element-size-dependent damage modeling can be applied to simulate the ductile crack growth behavior of a through-wall cracked pipe.