摘要：landing gear lower drag stay is a key component which connects fuselage and landing gear and directly effects the safety and performance of aircraft takeoff and landing. To effectively design the lower drag stay and reduce the weight of landing gear, Global/local Linked Driven Optimization Strategy(GLDOS) was developed to conduct the overall process design of lower drag stay in respect of optimization thought. The whole-process optimization involves two stages of structural conceptual design and detailed design. In the structural conceptual design, the landing gear lower drag stay was globally topologically optimized by adopting multiple starting points algorithm. In the detailed design, the local size and shape of landing gear lower drag stay were globally optimized by the gradient optimization strategy. The GLDOS method adopts different optimization strategies for different optimization stages to acquire the optimum design effect. Through the experimental validation, the weight of the optimized lower dray stay with the developed GLDOS is reduced by 16.79% while keeping enough strength and stiffness, which satisfies the requirements of engineering design under the typical loading conditions. The proposed GLDOS is validated to be accurate and efficient in optimization scheme and design cycles. The efforts of this paper provide a whole-process optimization approach regarding different optimization technologies in different design phases, which is significant in reducing structural weight and enhance design tp wid 1 precision for complex structures in aircrafts.

摘要：In the passive turning state,the helicopter turns through the tail rotor force and the friction of the ground to the *** practice,it is found that the helicopter will turn difficultly under low aircraft ground speed or static *** paper takes a certain type of helicopter as the research object,and establishes the dynamic model of helicopter ground turning motion based on the basic theory of *** model takes into account the six-degree-of-freedom motion model of the helicopter body,the motion model of the landing gear buffer,the tire mechanics model and the friction characteristics of the strut friction *** dynamic simulation of the helicopter right angle turn and static turn is carried out,and the influence of parameters such as tail rotor pull,taxi speed,tail wheel stability distance on the dynamic response of the turn is *** results show that under the same ground taxing speed,the tail wheel angle increases with the increase of tail rotor *** the tail rotor force is the same,the tail wheel angle increases with the increase of ground taxing *** the helicopter is completely static,it is the most difficult to turn,which requires much bigger force of the tail rotor to *** addition,the change of the stability distance of the tail wheel has an obvious influence on the *** the stability distance is doubled,the tail rotor force will be reduced by 30%to the same angle of the tail wheel.