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Explore the interface between aeroelasticity, flight dynamics and
control in this fresh, multidisciplinary approach. New insights
into the interaction between these fields, rarely separately
considered in most modern aircraft, are fully illustrated in this
one-of-a-kind book. The comprehensive, systematic coverage will
enable the reader to analyse and design next-generation aircraft.
Presenting basic concepts in a rigorous yet accessible way, the
book builds up to state-of-the-art models through an intuitive
step-by-step approach. Both linear and non-linear attributes are
covered, and by revisiting classical solutions using modern
analysis methods this book provides a unique, modern perspective to
bridge the gap between disciplines. Numerous original numerical
examples, including online source codes, help to build intuition
through hands-on activities. This book will empower the reader to
design better and more environmentally friendly aircraft, and is an
ideal resource for graduate students, researchers and aerospace
engineers.
Active integral twist control for vibration reduction of helicopter
rotors during forward flight is investigated. The twist deformation
is obtained using embedded anisotropic piezocomposite actuators. An
analytical framework is developed to examine integrally-twisted
blades and their aeroelastic response during different flight
conditions: frequency domain analysis for hover, and time domain
analysis for forward flight. Both stem from the same
three-dimensional electroelastic beam formulation with
geometrical-exactness, and axe coupled with a finite-state dynamic
inflow aerodynamics model. A prototype Active Twist Rotor blade was
designed with this framework using Active Fiber Composites as the
actuator. The ATR prototype blade was successfully tested under
non-rotating conditions. Hover testing was conducted to evaluate
structural integrity and dynamic response. In both conditions, a
very good correlation was obtained against the analysis. Finally, a
four-bladed ATR system is built and tested to demonstrate its
concept in forward flight. This experiment was conducted at NASA
Langley T ansonic Dynamics Tunnel and represents the
first-of-a-kind Mach-scaled fully-active-twist rotor system to
undergo forward flight test. In parallel, the impact upon the
fixed- and rotating-system loads is estimated by the analysis.
While discrepancies are found in the amplitude of the loads under
actuation, the predicted trend of load variation with respect to
its control phase correlates well. It was also shown, both
experimentally and numerically, that the ATR blade design has the
potential for hub vibratory load reduction of up to 90% using
individual blade control actuation. Using the numerical framework,
system identification is performed to estimate the harmonic
transfer functions. The linear time-periodic system can be
represented by a linear time-invariant system under the three modes
of blade actuation: collective, longitudinal cyclic, and lateral
cyclic.
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