| Safety is the most basic and the most important requirement of civil aircraft. With the development of civil aviation industry, the higher requirement about safety of the aircraft is put forward. In order to guarantee the safety of passengers and aircraft structure, foreign civil aircrafts usually add an emergency breakaway design in the connection of main landing gear and wing or fuselage. When the high overload situation appears, the main landing gear will be separated from the wing and the fuselage. Based on the multi-body dynamics theory and the software LMS Virtual. Lab Motion, the dynamic model of the landing gear emergency breakaway for large civil aircraft is studied.According to the airworthiness regulations, the structural design requirements of the landing gear emergency breakaway design is discussed and some landing gear emergency breakaway designs of foreign civil aircrafts are compared and studied in the paper. A civil aircraft is taken as the research object and then a corresponding emergency breakaway scheme of landing gear is presented. Depending on the software of LMS Virtual. Lab Motion, the dynamic models of the main landing gear and the aircraft containing nose landing gear and fuselage are built. By simulating the main landing gear model of free drop, large sink speed landing and taxiing obstacles and analyzing the disconnection point loads,the limited loads,the breakaway loads and the failure sequence are concluded. By simulating the aircraft model of landing and taxiing obstacles,the simulation results of single main landing gear model are compared and the influence of some parameters to the disconnection point loads of the main landing gear are studied. It shows that the limited load of the side brace pin determined through the free drop test is not so accurate. The limited load need to be determined by the limited working condition of asymmetric landing,which will meet to the requirements of normal use and landing gear emergency breakaway. |
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