Analysis of an Actively Twisted Rotorby Multi - Body Global

The paper presents a procedure and the integrated tools for the aeroelastic analysis of an Active Twist helicopter Rotor (ATR). The active twisting of rotor blades is carried out by induced-strain actuators distributed into the structure of the blade. Active bre composites (AFC), made of piezoelectric bres actuated by interdigitated electrodes (IDE), are used to obtain anisotropic induced-strain actuation capable of twisting the blade. The elastic, inertial and piezoelectric properties of the blade section are determined by a dedicated semianalytical formulation that accounts for the non-homogeneity and the anisotropy of the elastic and piezoelectric materials. A three-dimensional FEM analysis of the piezoelectric bre with IDE is used to estimate the equivalent material properties required for the blade section characterisation. A four-blade, articulated rotor is analysed in hover and forward ight conditions. The system is modelled by an original multi-body formulation, implemented in a code named MBDyn (Multi-Body Dynamics). The equilibrium equations and the deenitions of the momenta are written for each body, together with the constraint equations, in the spirit of a Redundant Coordinate Set formulation. The blades are modelled as beam elements, by an original nite volume formulation for the analysis of nonlinear, initially curved and twisted beams subject to large displacements and rotations. The formulation is extended to include the eeects of embedded piezoelectric devices as actuators. Electric and control-related degrees of freedom and elements have been added to MBDyn. Preliminary results related to the actuation authority of the active blade are presented