ANALYSIS AND RELIABILITY BASED DESIGN OPTIMIZATION OF FLUID-STRUCTURE INTERACTION PROBLEMS SUBJECT TO INSTABILITY PHENOMENA

In recent years, the aircraft manufacturers benefit a lot from the computer aided design, analysis, and optimization technologies in reducing the cost of their product development phase which is composed of costly prototypes and wind tunnel experiments. With these observations, the application subject of this project is chosen as the computational fluid-structure interaction and aeroelastic instabilities which is one of the most complicated areas of aerospace engineering.  The objective is, in the first phase, to achieve the design optimization of these multidisiplinary problems by using deterministic methods and in the second phase, to achieve the reliability based design optimization by integrating the uncertainty analysis with the former phase.

Aeroelasticity examines the interaction and energy transfer between the elastic structures of an aircraft (like wings and ailerons) with the aerodynamic forces acting on it during the flight, and also the catastrophic instability phenomena (such as flutter and divergence) which occur when this interaction can not be damped under control.  Preventing flutter has been and still is the most challenging subject in aerospace industry especially after the 1940s, when with the better engines and the higher flight speeds, the flutter was seen more. When looked in the aerospace history, one can see lots of accidents happened due to flutter. Recent examples like, the crash of Taiwan IDF fighter in 1992 and in the same year the crash of American fighter F-22 prototype, in 1997 the crash of American “Stealth Fighter” can be given.

This career project aims to develop a Multi-Disciplinary Optimization (MDO) methodology to enable the analysis of static and dynamic instabilities in fluid-structure interaction problems and moreover accounting for and prevention of the instabilities as yet the aircraft is in computer aided engineering phase.  Furthermore, the “Structural Reliability Theory” will be added to this methodology, to apply Reliability Based Design Optimization (RBDO) technology to Fluid-Structure Interaction (FSI) problems subject to instabilities.

During the project, this methodology will be mostly developed with applications to aeroelastic studies towards design of  civil and military aircraft wings and/or complete geometries. However, the developed technology can be a starting point to other broad subjects in aerospace engineering such as helicopter “rotarywing-aeroelasticity”, “aircraft turbine engine aerothermoelasticity”, wind turbine “aeroservoelasticity” and aeroelasticity applications in UAVs (Unmanned Air Vehicle),  moreover to other engineering fields where one can see fluid-structure interaction such as the design of compressor valves or fan blades etc.