Component Model Parameter Updating for Landing Gear Linkages with Flexible Joints

This paper presents a practical and effective framework for updating landing gear finite element component models such that the updated reduced-order component mode synthesis model of the entire assembled system can provide accurate structural dynamic results in any possible landing gear configuration. By constructing component mode synthesis matrices using updated finite element parameters, the requirement to experimentally derive the modes required for component mode synthesis is avoided. Because it is impossible to directly measure joint frequency response functions, the experimental substructure boundary conditions are made to mimic natural joint-link connectivity by using flexible-hinged boundaries with links and joint hinges in arbitrary orientations. This exploits the fact that experimental frequency response functions obtained away from the joints can contain information about the joint dynamics, which result in resonance frequency shifts. The updating of each component model in multiple possible configurations is performed using a genetic algorithm with bounded inequality constraints on the updating parameters and nonlinear constraints on frequency response function parameters (natural frequencies, antiresonances, and fixture motion). Afterward, the updated flexible-hinged supports are analytically removed for final system component mode synthesis assembly. The effectiveness of the proposed framework is demonstrated with an experimental case study on a simplified landing gear model. Overall, the updating method can enable further dynamic testing of the complete system in a virtual environment, thereby reducing the need for extensive experimental testing on entire landing gear assemblies.