An algorithm for designing nonlinear springs, or nonlinear dampers, using a mechanical force generator and its application to an aircraft landing gear

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yildiz_fatih_thesis_73.pdf

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2021-12-03

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Yıldız, Fatih

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The landing gear system is one of the most critical aircraft sub-systems that takes part in the landing, taxi and take-off phases of every aircraft. Its main function is the absorption of part of aircraft's kinetic energy during landing. There are different types of shock absorbers to perform this task. The performance of the shock absorbers has developed a lot after the invention of air-oil type shock absorbers. However, increasing the performance of these shock absorber elements is still a field of research followed by companies and institutions. Mechanical Force Generators, on the other hand, are novel over-constrained mechanisms that are known for low friction and shaking force properties. A very important property of Mechanical Force Generator is being flexible to be designed for any required force characteristic. This thesis study consist of mainly three sections. Firstly, a design methodology for Mechanical Force Generator design is developed. For this design methodology, Mechanical Force Generator has been considered for two different purposes: a non-linear equivalent spring and a non-linear equivalent damper. Then, spring mass damper model was developed for landing gear modeling. This model is validated against the results of a test performed by the National Advisory Committee for Aeronautics. Using a spring mass damper model, an optimization is sought on the landing gear used in this test. The methods and approaches to find the optimum spring and damper characteristics are explained. In the last, using the optimum spring damper characteristics determined in the optimization, the design of Mechanical Force Generator is followed for the landing gear. The applicability and feasibility of the design on landing gear are presented and discussed. Throughout the study, special properties of Mechanical Force Generator are investigated, and different areas it may be utilized are evaluated and recommended at the end of the study.

Subject Keywords

Aircraft landing gear, Shock absorber efficiency, Mechanical force generator

URI

https://hdl.handle.net/11511/95108

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Graduate School of Natural and Applied Sciences, Thesis

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Citation Formats

F. Yıldız, “An algorithm for designing nonlinear springs, or nonlinear dampers, using a mechanical force generator and its application to an aircraft landing gear,” M.S. - Master of Science, Middle East Technical University, 2021.