Fatigue life evaluation in composite rotor blade of multipurpose helicopter

The prediction of fatigue life and strength of the composite rotor blade for multipurpose helicopter was studied using a residual strength degradation concept. A flight-by-flight load spectrum was introduced on the basis of FELIX standard data. The composite structure analysis was performed to obtain the local stress near blade root in laminate skin and glass roving spar where fatigue damage was most severely anticipated. The fatigue test in the structural specimen of the rotor blade was also carried and compared with predicted results.