Multidisciplinary Design Optimization of Nose Landing Gears with Two Degrees of Freedom Considering Out of Plane Loading and Actuator Performance

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Ryu, Jonathan
Multidisciplinary Design Optimization (MDO) , Landing Gear , Kinematics , Dynamics , Structural Optimization
Multidisciplinary design optimization (MDO) is a mathematical optimization technique for designing engineering systems that involve multiple disciplines. By implementing the MDO technique, engineers can design complex systems by simultaneously considering multiple branches of physics without manual iterations. The design of lightweight retractable aircraft landing gear is a sophisticated multidisciplinary problem. It is difficult to finalize the design through manual iterations, especially under the demands of an accelerated product development process. MDO methodology has been previously developed to design a planar four-bar mechanism for retractable nose landing gears with one degree of freedom (DOF) to minimize mass with simultaneous structural and kinematic optimization. Although the methodology has demonstrated the viability of MDO for designing a retractable nose landing gear under the demands of a shortened product development process, there is no existing MDO methodology that can be implemented to design lightweight retractable nose landing gears with two DOF considering hydraulic cylinder performance and out-of-plane load cases. This thesis presents an MDO methodology for simultaneous structural and multi-body dynamic optimization of retractable nose landing gear main fitting, side brace, and lock link assemblies, where the goal is to minimize mass. The methodology has been implemented using Python to generate three different landing gear designs for three commercial aircrafts with out-of-plane load cases based on European aircraft certification requirements. The resultant designs demonstrate that the proposed MDO methodology can determine an ideal wheel diameter, cross-sectional dimensions, and revolute joint distances of all the landing gear members in the preliminary design phase.
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