Blade optimization is more than ever a crucial activity for helicopter manufacturers, always looking for performance improvements, noise reduction and vibratory comfort increase. Latest studies have led to design new blade concepts including a double swept plan shape, an evolutionary and increased twist angle at the tip and a new layout for internal components like roving spars. Such blades exhibit a highly coupled behavior between torsion, longitudinal and bending motions that should be accurately modeled for predictive numerical tools. In this research a highly accurate beam finite element is formulated in the rotating frame to improve the static deformation calculation under aerodynamic and centrifugal loads and thus enhance dynamic and stability analysis usually performed for a helicopter development. Numerical and experimental investigations are performed to demonstrate the model reliability both for academic beams with extreme shape and for actual blade design.

In order to predict the lateral rotordynamics of a high speed induction motor, an optimization procedure is proposed for identifying the equivalent constitutive properties especially those of the magnetic core: an assembly of lamination stack, tie rods and short-circuit rods. Modal parameters predicted by a finite element (FE) branched model based mainly on beam elements, and measured on an induction motor are included in an original energy functional. The minimization of this functional by using the Levenberg-Marquardt algorithm permits extracting the equivalent constitutive properties of the lamination stack.