Damage mechanics and composite behaviour

Abstract The concept of damage in fibre-reinforced composites is discussed in analytical and practical terms. The damage which occurs mainly in the resin and interfaces between resin and fibres is considered to be the same in both static and cyclic loading conditions. Under cyclic loading, damage may be interpreted and monitored from changes in strain or form and position of the hysteresis loop, but the relation between strain and failure is not clear. Failure envelopes can be constructed on the basis of limiting tensile and compressure stresses and a constant cyclic stress limit. Under block loading, the interaction of damage produced by different stress levels needs further investigation. A model of damage growth under cyclic loading is presented.