Variationally consistent eXtended FE model for 3D planar and curved imperfect interfaces

•A variationally consistent 3D XFEM model for planar and curved thin imperfect interfaces is proposed.•Bulk mesh size independent results are obtained.•The implementation in standard XFEM models is straightforward.•Blending and quadrature subdomains are avoided.•Comparisons with spring-like models show that the asymptotic behavior is consistently recovered.

We propose an eXtended Finite Element Method convergent to the asymptotic solution of a thin interface problem for both planar and curved imperfect interfaces in three dimensions. The main advantage over standard cohesive-zone models is the bulk-mesh size independence. With respect to standard eXtended Finite Element Method, in the proposed procedure, blending and quadrature sub-domains are not required. The focus is on the evaluation of the accuracy of the proposed approach in solving three-dimensional benchmark tests. The numerical results are compared with those available from analytical solutions and spring-like interface models.