Spanos, Pol D.2012-09-062012-09-062012-09-062012-09-062012-052012-09-05May 2012Sukut, Thomas. "Nonlinear Aeroelastic Analysis of UAVs: Deterministic and Stochastic Approaches." (2012) Master’s Thesis, Rice University. <a href="https://hdl.handle.net/1911/64686">https://hdl.handle.net/1911/64686</a>.https://hdl.handle.net/1911/64686Aeroelastic aspects of unmanned aerial vehicles (UAVs) is analyzed by treatment of a typical section containing geometrical nonlinearities. Equations of motion are derived and numerical integration of these equations subject to quasi-steady aerodynamic forcing is performed. Model properties are tailored to a high-altitude long-endurance unmanned aircraft. Harmonic balance approximation is employed based on the steady-state oscillatory response of the aerodynamic forcing. Comparisons are made between time integration results and harmonic balance approximation. Close agreement between forcing and displacement oscillatory frequencies is found. Amplitude agreement is off by a considerable margin. Additionally, stochastic forcing effects are examined. Turbulent flow velocities generated from the von Karman spectrum are applied to the same nonlinear structural model. Similar qualitative behavior is found between quasi-steady and stochastic forcing models illustrating the importance of considering the non-steady nature of atmospheric turbulence when operating near critical flutter velocity.application/pdfengCopyright is held by the author, unless otherwise indicated. Permission to reuse, publish, or reproduce the work beyond the bounds of fair use or other exemptions to copyright law must be obtained from the copyright holder.Nonlinear aeroelasticityTurbulenceUnmanned aerial vehicleFlutterHigh-altitude long-enduranceHarmonic balanceThesis2012-09-06123456789/ETD-2012-05-155