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6DOF Flight Dynamics Modeling of a Flexible Flapping wing using Unsteady Aerodynamics

Zare, Hadi | 2018

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  1. Type of Document: Ph.D. Dissertation
  2. Language: Farsi
  3. Document No: 51755 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Pourtakdoust, Hossein
  7. Abstract:
  8. A complete 6DOF flight dynamic model of an elastic flapping wing (EFW), integrated with unsteady aerodynamic theory is developed. In this respect, initially efficient high fidelity modules for EFW structural dynamics (SD) as well as unsteady aerodynamics loadings (UAL) to be coupled with its flight dynamics are prepared. A modal approach is followed to model structural dynamics of plain and 3D EFWs. This is in contrast with the Euler-Bernoulli beam theory that is mostly utilized for SD in the existing literature. In addition, due to the possibility of large wing deformations as well as the existence of non-linear displacement regime for realistic EFW flights, non-linear modal approaches such as “Implicit Condensation” (IC) and “Implicit Condensation and Expansion” (ICE) are studied and modified into an innovative MICE model developed for the current research. In the proposed iterative method of SD solution the non-linear coefficients are also determined and they affect both the generalized coordinates as well as the final displacements. Comparing the results of the proposed MICE with other linear and non-linear SD modal methods (IC and ICE) shows an enhancement in the accuracy. With respect to the aerodynamics of EFW, initially a “Modified Strip Theory” (MST) plus its upgraded version called MST-Stall were chosen as the base methods. Moreover, due to several deficiencies associated with the basic assumptions of existing aerodynamic theories a novel GMST model is later proposed that takes wing section curvature into account. Subsequently, an integrated MST-Flex model was developed that considers the dynamic effect of the wing section curvature plus some other unsteadiness phenomenon. It is important to note the both proposed new models of GMST as well as MST-Flex have been validated against experimental data. Within the general scope of flight dynamics modeling, as the main EFW body dynamics couples with those of the wing and tail, a multi-body modeling scheme was used in derivation of an integrated solid-fluid flight dynamics equation for the first time. The integrated scheme has been simulated for a typical EFW whose results are verified with ADAMS in some cases. Finally, some general 6DOF simulations of EFW considering flow unsteadiness have been performed followed by a sensitivity analysis study over some key EFW design and kinematic parameters
  9. Keywords:
  10. Flapping Wing ; Flexible Wing ; Dynamic Modeling ; Aeroelasticity ; Unsteady Aerodynamic ; Modal Analysis

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