Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Mechanical Engineering

First Advisor's Name

Yiding Cao

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Ibrahim Nur Tansel

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Bilal El-Zahab

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Leonel E. Lagos

Fourth Advisor's Committee Title

Committee member

Keywords

inertia force loadings, finite element analysis, reciprocating airfoil-driven (RA), reciprocating wing (RW), wing topology optimization, reciprocating-airfoil-driven VTOL aircraft, S1223, FEA and machine learning, random forest regression (RFR), support vector regression (SVR)

Date of Defense

11-4-2022

Abstract

The evolution of air transportation has been progressively slow in the last two decades, and the primary means of air transportation remains to be fixed-wing aircraft and a small subset of rotorcraft, like helicopters. The development and demand for hybrid vertical takeoff and landing (VTOL) vehicles that can cruise like fixed-wing aircraft and take off like helicopters have opened the possibility of improved future air travel. However, hybrid VTOL aircraft use rotary blades for takeoff and landing operations, which could result in structural difficulties such as vibrational problems, restricted flight speed, poor endurance, relatively low energy efficiency, difficulties in the transition from VTOL to fixed-wing mode, and safety concerns. The recently invented reciprocating airfoils (RA) wing might address the abovementioned shortcomings. The RA wing is regarded as a new fundamental wing due to its distinct linear reciprocating motion during VTOL operation and its smooth transition from VTOL to fixed-wing operation. Thus, the RA-driven VTOL unoccupied aerial vehicle (UAV) could be superior to existing hybrid VTOLs.

However, an RA wing may be subject to strong inertia force because of the reciprocating motion, and its structural analysis is critical to the development of RA- based VTOL UAVs. The stress-carrying capacity of the RA wing for use in the RA-driven VTOL UAV is assessed in the first part of this study, which involved designing the RA wing and conducting a feasibility study. The results show that the RA wing is resilient and capable of withstanding strong inertia forces during VTOL operation. The RA wing was then redesigned in the second phase to simulate how it would operate at maximum speed. The results demonstrated that the RA wing performs adequately well at maximum speed. The final stage entailed structural optimization to improve the stress state of the wing at the maximum lift to obtain better results. The stress result of the topology-optimized wing decreased by 44.6%, and the factor of safety (FoS) increased by 78%. This is a significant improvement in developing a structurally sound wing that meets the needs of the VTOL operation in an RA module. A preliminary investigation into machine learning (ML) modeling and finite element analysis (FEA) to anticipate the mass and FoS for the RA wing were also carried out. The findings offer a good foundation for future ML applications that estimate FEA structural results for the RA wing.

The high lift during takeoff and landing and the seamless transition to a fixed- wing operation are some of the unique advantages of the RA VTOL UAV over existing VTOL UAVs despite the challenge of high inertia stress that accompanies the RA wing. This study showed the load-carrying capability of the wing structure and its suitability for integration with the RA UAV module. The outcomes of this study demonstrate and validate the reciprocating wing’s performance and significantly contribute to the future development of RA VTOL UAVs.

Identifier

FIDC010943

ORCID

https://orcid.org/0000-0002-7234-1723

Previously Published In

J. O. Imumbhon, M. D. Alam, and Y. Cao, Design and structural analyses of a reciprocating s1223 high-lift wing for an ra-driven vtol uav, Aerospace, vol. 8, no. 8, p. 214, 2021.

J. O. Imumbhon, M. Landazuri, and Y. Cao, Structural and cfd analyses of a reciprocating-airfoil (ra) driven uav wing under maximum lift and inertia forces, Drone Systems and Applications, vol. 10, no. 1, pp. 287–308, 2022.

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