Total Fatigue Life Assessment of Complicated Structures

SIF and non-SIF based approaches are used to study the damage/crack growth involving complex crack shapes under complicated loading conditions. In the SIF based approach, we use alternating, non-hypersingular Symmetric Galerkin Boundary Element Method (SGBEM)-Finite Element Method (FEM) formulation to study both 3D and 2D crack growth situations. This technique enables study of surface or embedded 3D cracks growing in non-coplanar mode, 2D through crack growing in non-collinear way, and transitioning of 3D into 2D cracks. A large number of benchmark problems will be solved to validate the methodology and case studies will be conducted to demonstrate proposed method"s superiority. In the non-SIF based approach, we explore the use of Peridynamics to study fracture processes and application to fatigue problems. Peridynamics is a non-local approach , where material particles exert influence within a neighborhood distance as opposed to the classical local approach. The most important part in Peridynamics is in the formulation of constitutive laws to express the bond forces between material points. Owing to its formulation expressed in integral forms, it is well suited to discontinuities such as cracks. In this study, we explore linking continuum damage mechanics models with Peridynamics for applications involving HCF and composites.