Structural, shape and performances optimization in helicopter rotor leads to design composite blades initially curved and twisted. This design yields a highly coupled behavior between torsional, longitudinal and bending motions. A beam finite element is proposed to predict the static deformation under aerodynamic and centrifugal loads and achieve dynamic and stability analysis. This elastic model is to be implemented in a comprehensive rotorcraft analysis code, which means accuracy, reliability and calculation time compromise. The new model is designed to fit any rotor hub configuration that includes articulated and hingeless rotor with various lead-lag damper technical solutions. Model definition relies on nonlinear equations of motion and on an energetic equilibrium of rotating blades.