Abstract

Airbus High Lift System Test Department at Bremen successfully conducts since several years Virtual Testing (VT). The approach of Virtual Testing by means of computer simulations of physics-based models has been applied for all major aircraft development programmes of the last years since A380. The preferred simulation methodology is multibody simulation (MBS). Depending on the test objective and the mechanism that is simulated, specific parts need to be modelled as flexible bodies. Generally, these flexible bodies are represented by modal neutral files (MNF), derived from existing linear static finite element method (FEM) models. This involves several, time-consuming pre-processing tasks such as extraction of the body under consideration from an integrated FEM model or the assignment of inertias that are not necessarily contained in the linear static FEM. A specific type of high lift kinematics (Fowler kinematics) constitutes a special case that involves a carriage that travels on a flexible track beam. In FEM, this is realized by dedicated models for dedicated positions of the carriage on the track. Implementation is done for instance by changing locations of grids or by GENEL statements with changing parameters. Hence, the mechanism’s effective, position-depending flexibility is correctly modelled. In MBS the default way of modelling is to use a translational joint between the carriage and a rigid track, which in terms is connected to the flexible beam. This connection is effected by a rigid body element (RBE). This leads to a constant, mean effective stiffness of the beam, independent of the actual carriage position. Depending on the ratio between beam flexibility and applied load, this can lead to an unacceptable error. Hence in scope of an R&T project an alternative approach is investigated and demonstrated. The carriage is connected to the track by a multidimensional spring with position-dependent coefficients. The coefficients either can be taken directly from available GENEL parameters or can be derived by simple static FEM analyses (application of unit loads). Position dependency in the MBS model is achieved by spline interpolation. This leads to both, a correct consideration of the position-dependent stiffness as well as a simplification of the pre-processing process. The modelling approach is integrated into a table defined, script-based model creation process which addresses the need for robust, efficient and traceable model creation (cf. Simulation Process Data Management, SPDM).