Methods for structural design, control, and testing of flexible aircraft structures are considered. Focus is on nonconventional aircraft configurations and control concepts. The interaction between analysis and testing is a central topic and all studies include validation testing and comparison between computational and experimental results. The first part of the thesis is concerned with the de...

Chaotic motions of a two dimensional airfoil with coupled structural nonlinearities, both in pitch as well as plunge degrees of freedom, are investigated via a numerical integration method. The original system of coupled integro-differential equations governing the motion of the present aeroelastic model is transformed into a simple system of six ODEs. Complex dynamical behaviors are revealed a...

This work presents the analysis of nonlinear aeroelastic time series from wing vibrations due to airflow separation during wind tunnel experiments. Surrogate data method is used to justify the application of nonlinear time series analysis to the aeroelastic system, after rejecting the chance for nonstationarity. The singular value decomposition SVD approach is used to reconstruct the state spac...

The procedures to assess the critical aeroelastic state of an aircraft with the AESIM simulation method are described. The main innovation is the identification with MIMO-class methods which opens up possibilities for efficient usage of aeroelastic simulation methods. Experience with recent applications is reported. ANALYSIS OF COMPUTATIONAL AEROELASTIC SIMULATIONS BY FITTING TIME SIGNALS Micha...

Aeroelastic instabilities are an important factor in the design of modern high-speed, flexible aircraft. The current trend is toward the creative use of composites to delay these instabilities. To obtain an optimum design, an accurate as well as efficient model is required. As a first step towards this goal, aeroelastic analysis is carried out for a swept composite box beam, using a linear stru...

This paper numerically investigates the effect of chordwise flexibility on the dynamic stability of compliant airfoils. A classical two-dimensional aeroelastic model is expanded with an additional degree of freedom to capture time-varying camber deformations, defined by a parabolic bending profile of the mean aerodynamic chord. Aerodynamic forces are obtained from unsteady thin airfoil theory a...

in this paper, a new algorithm for system identification based on frequency response is presented. in this method, given a set of magnitudes and phases of the system transfer function in a set of discrete frequencies, a system of linear equations is derived which has a unique and exact solution for the coefficients of the transfer function provided that the data is noise-free and the degrees of...

power transformers are key components in electrical power supplies and their failure could cause severe consequences on continuity of service and also generates substantial costs. identifying problems at an early stage, before catastrophic failure occurs, is a great benefit for reliable operation of power transformers. frequency response analysis (fra) is a new, well-known and powerful diagnost...

A linear, aeroelastic analysis of a low aspect ratio swept back trapezoidal wing modeled as a cantilever plate is presented. An analytical and numerical formulation for both the aerodynamic forcing and structural response of the wing was developed. The analytical model uses a three dimensional time domain vortex lattice aerodynamic method. A Rayleigh-Ritz approach has been used to transfer equa...