Multiscale analysis of fatigue crack initiation life for unidirectional composite laminates

Abstract

Three dimensional (3D) finite element analysis along with a damage model based on kinetic theory of fracture (KTF) are used to determine the onset of fatigue crack initiation in unidirectional carbon fiber reinforced composites. In addition, the Multicontinuum theory (MCT) and micromechanics are employed separately to enable the assessment of the stress state distribution at the length scale level of the constituents. While the MCT is implemented in the macroscale model formulation, micromechanical analysis of a representative unit cell has been also developed to capture the stress field in the micro length scale level. An ABAQUS™ user material (UMAT) subroutine has been developed and used for implementing the formulation. Numerical examples of various tests including tension, three point bending, four point bending, and short beam shear test of a unidirectional (UD) laminate are considered and the results are compared against actual test data. A detailed discussion, challenges and future plans on the applicability of the KTF are concluding this work.