Multibody Simulation in the Integrated Design of Semi-Active Landing Gears

Abstract

The paper presents a technique for an integrated aircraft-landing gear design using multibody simulation (MBS). The MBS technique is aimed at the simulation of the dynamics of a technical system in its entity. It has proven to be a well balanced compromise between the requriement of "fast", "robust", and "exact" simulation, thus assisting the process of virtual prototyping. An aircraft model is set up using SIMPACK, DLR's prime MBS tool. The aircraft model presented is based on a large civil aircraft consisting of a finite element structure for fuselage and wings, landing gear models from CAD, control structures from a control design tool, and measured input data for sevral runway profiles. The objective is to achive an optimal landing gear design with respect to the aircraft as a whole. Therefore, a multi-objective optimization loop is used to optimize landing gear parameters using criteria covering both the landing and rolling performance, i.e. resulting loads, stress and comfort at several locations at the aircraft structure. In addition to the conventional suspension design, this method has been used to propose a control strategy for semi-active damping of the nose landing gear that reduces runway induced vibrations of fuselage and wings, thus increasing comfort and minimizing airfram loads.