Modeling a Stiff-Inplane Tiltrotor Using Two Multibody Analyses: a Validation Study

The objective of this investigation is to illustrate a modular approach in the development and validation of sophisticated rotorcraft analytical models within the framework of multibody dynamics simulations. This approach is demonstrated with the development of a stiff-inplane tiltrotor wind-tunnel model using two multibody dynamics analyses. The two multibody dynamics codes used are: DYMORE and MBDyn, which are both capable of supporting comprehensive, multibody-based rotorcraft modeling and dynamic simulation. The multibody dynamics models developed in this effort include the gimballed hub, rotor blades, pitch links, swashplate, conversion actuators which are attached to the pylon, and the elastic wing. The natural frequencies, mode shapes, and stability characteristics of key sub-component structures and the kinematic couplings of rotor system are correlated with the predictions of the two analyses. Furthermore, experimental data obtained in ground vibration tests and wind-tunnel tests is extensively used to validate the analytical models. The validated models are then used to predict the tiltrotor whirl-flutter stability boundary, which shows good agreement with the experimental measurement