Multi-body Dynamics Structure-preserving Analysis Of Undercarriage

Undercarriage is the important force support element during the takeing off andlanding processes, the dynamical properties of which is an important factor related tothe safty of the aircraft. There are wide range of relative motions among the parts ofthe undercarriage, thus, undercarriage is a typical multi-body system with constraint.It is well known that the constraints default is the main difficulty in multi-bodysystem problems. Based on the structure-preserving idea, the constraint is consideredas the “structure” of the system and the follwing jobs are done in this thesis:1) Establishing the dynamic model of the undercarriage during the takeing offand landing processes. This model is established based on the Hamilton variationalprinciple considering the load situations, the geometrical constraints.2) Studying the expansion process of the undercarriage. The second orderaccuracy symplectic precise integration scheme is used to study the expansionprocess of the undercarriage and the constraints default is disscussed.3) Studying the pack-up process of the undercarriage. The second order accuracysymplectic precise integration scheme is used to study the pack-up process of theundercarriage and the constraints default is disscussed. From the simulating results,the appropriate active force is obtained that satisfies the engineering requirements.The work of this thesis broadens the application fields of the structure-preservingmethod. At the same time, the results of this thesis provides some good references forthe further optimization design of the undercarriage.