A progressive multi-scale fatigue model for life prediction of laminated composites

Abstract

This article presents a multi-scale progressive micro-mechanical fatigue model. The model employs fundamental equation of the kinetic theory of fracture to calculate damage parameters of both fiber and matrix during cyclic loading. In order to adapt the equation, required material coefficients of the constituents can be achieved from fatigue test results of longitudinal and transverse unidirectional composites, only. Sharing stress capacities of fiber and matrix are determined using a modified progressive micro-mechanical bridging model in the presence of damage. The damage parameters in the constituents are calculated employing two different equivalent scalars. However, during sinusoidal load application, these damage parameters are also updated using a first kind Bessel function of amplitude stresses in the constituents as well as their material coefficients. The enhanced formulation is then implemented into the commercial finite element software of ABAQUS via a developed user material (UMAT) subroutine utilizing a suitable failure criteria and an own solution algorithm. Advantages of the proposed model are assessed and comparisons with available solutions are presented.