Perpustakaan Digital ITB

Cracks are a critical structural failure mode, yet conventional FEM struggles with mesh-dependent remeshing and representing crack discontinuities. The Phase-Field Method offers an alternative, modeling cracks as a continuous damage field. This study develops J-integral script using a discrete lineintegral formulation with symmetric/antisymmetric decomposition to isolate Mode I and II intensity factors under mixed-mode loading, integrated with an Abaqus UEL phase-field subroutine. Validated across single-edge, centercrack, and center-slant specimens against handbook solutions and Abaqus’s Equivalent Domain Integral method, the FEM script agrees closely with analytical results, with errors below 6% from the second contour for pure Mode I. The phase-field version matches this for Mode I but loses path-independence at larger contours due to degraded stiffness affecting the recovered displacement field. For mixed-mode loading, the decomposition stays reliable for the dominant factor but fails for the subordinate one when the two differ substantially, as diffuse crack representation corrupts the near-cancellation it relies on. A sensitivity study across lc = 0.4–0.8 mm shows Mode I is insensitive to lc, while lc = 0.6 mm minimizes error and scatter for the dominant mode in mixed-mode cases.