Since Multi Body System (MBS) codes have been proved to be potentially powerful simulation tools in the whole range of helicopter rotor dynamics, here the question of modelling the free flying helicopter in a MBS dynamical simulation model is highlighted. In order to take into account also the characteristics of the flexible rotor-nacelle interface, the special modelling features of the MBS code have been used. The objective of this research work are modelling techniques for decribing the dynamical behaviour and the struchtural interaction between helicopter rotors - main and tail rotor - and the nacelle of a free flying helicopter. Here the focus lies on the coupling of the rotating structure of the fully elastic main rotor and the non-rotating parts of the body structure. As simulation platform the 9[to] generic model "Helicopter H9" has been developed in this context. Representing the research object in this investigation it serves as a demonstrator model and as dynamic reference configuration for both the MBS and the FEM calculations. The "Helicopter H9" has a five blade main rotor with a diameter of D=16[m], a four blade tail rotor with a diameter of D=2.8[m] and a MTOW of 9118.4[to] (see Fig.1). The helicopter nacelle is modelled as a six degree of freedom rigid body, while the elastic main rotor has up to 2000 degrees of freedom. Investigated are modelling techniques for simulating the dynamics of the structural behaviour of the free flying helicopter in the frequency domain. In the case of the MBS simulation code the dynamical model requires a numerical linearization prior to the eigenvalue analysis. On the MBS side the commecial tool SIMPACK is tested while on the FEM side the inhouse tool GYRBLAD is used. It is shown how special joint modelling techniques like the usage of pseudo bodies with additional DOF are introduced into the "pure" MBS model to reach the aim of placing the required rotor mount positions without restrictions.
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