Performance Analysis of Composite Helicopter Blade Using Synergistic Damage Mechanics Approach

The damage behavior of a helicopter rotor blade made of carbon fiber polymer composite has been numerically investigated using a synergistic damage mechanics (SDM) model. Laminates of the quasi-isotropic stacking sequence [0/90/-45/+45]s have been considered in this study. The simulations were performed, corresponding to a hovering condition and for a range of the angles of attack and rotational speeds of the blade. The aerodynamic and centrifugal loads due to different angles of attack and rotational speeds have been computed by using fluid dynamics simulations. A structural analysis was then performed using the aerodynamic loads. Using the SDM model, the matrix crack density and crack multiplication were evaluated to predict the damage initiation site and maximum crack density occurring in the plies of the laminate under the operational conditions. It was observed that maximum crack appeared in the blade at extreme operational conditions; among the different plies, a -45 deg ply was cracked by the maximum amount. A crack density of around 0.9 crack/mm was predicted in the -45 deg ply at an operational condition with a 500 rpm blade rotation and an 18 deg angle of attack of the blade. The present study demonstrates application of the progressive damage modeling in designing a composite helicopter blade by considering its performance parameters.