Fatigue damage accumulation model based on stiffness degradation

Damage of composite materials is very complex under static and fatigue loads. It is important for mechanical behavior to model the damage of composite materials. To simulate fatigue damage and predicate the fatigue life of composite materials, a new fatigue model is given according to the strain equivalence principle and considering the deficiency of fatigue damage accumulation. T300/KH-304, which is recently studied, is a high capability composite material for aeroengine. All samples were tested in an SHIMADZ servo-hydraulic fatigue machine under computer control. The load was cycled at a frequency of approximately 4.1 Hz. Samples were carried in the constant amplitude fatigue test of the composite materials under different stress levels. This damage model was set up for T300/KH-304 laminate. The result of this model prediction is closer to the test than using S-N cure. The relative error is less than 2.4%. The fatigue damage evolution law of the composites materials could also be described.