DEVELOPMENT OF A NUMERICAL METHODOLOGY FOR THE SIMULATION OF THE FATIGUE INDUCED DELAMINATION IN COMPOSITE STRUCTURES

Composite materials are characterized by extraordinary strength and stiffness properties which can be strongly affected by intralaminar and interlaminar failure modes. Among the different damages, delaminations can be considerably influenced by the fatigue induced material properties degradation. Indeed, delamination propagation phenomena could begin at a fairly low number of cycles, progressively leading to the growth of the delaminated area and to the decrease of the global structural stiffness until the structural catastrophic failure. In this paper, a numerical procedure for fatigue induced delamination simulation has been developed. The mechanical behaviour of composite panels under cyclic loading conditions have been numerically investigated. The proposed approach, implemented in ANSYS® FEM software by using the Ansys Parametric Design Language (APDL) adopts a mesh and time step independent procedure based on the Virtual Crack Closure Technique (VCCT), combined with the Paris-Law formulation, which permits to take into account the local damage accumulation along the delamination front.