Finite element approach for modelling fatigue damage in fibre-reinforced composite materials

Today, a lot of research is dedicated to the fatigue behaviour of fibre-reinforced composite materials due to their increasing use in all sorts of applications. These materials have a quite good rating as regards to lifetime in fatigue, but the same does not apply to the number of cycles to initial damage, or to the evolution of damage. Composite materials are inhomogeneous and anisotropic, and their behaviour is more complicated than that of homogeneous and isotropic materials such as metals. A new finite element approach is proposed in order to deal with two conflicting demands: (i) due to the gradual stiffness degradation of a fibre-reinforced composite material under fatigue, stresses are continuously redistributed across the structure and as a consequence, the simulation should follow the complete path of successive damage states; (ii) the finite element simulation should be fast and computationally efficient to meet the economic needs. The authors have adopted a cycle jump approach which allows to calculate a set of fatigue loading cycles at deliberately chosen intervals and to account for the effect of the fatigue loading cycles in between in an accurate manner. The finite element simulations are compared against the results of fatigue experiments on plain woven glass/epoxy specimens with a [#45 degrees](8) stacking sequence. (C) 2001 Elsevier Science Ltd. All rights reserved.