This contribution is concerned with adaptive damping of plate-like structures equipped with a piezoelectric patch.
Damping of mechanical modes can be accomplished by connecting simple electrical impedances at the terminals
of the piezoelectric patch. For reason of miniaturization and robustness with respect to a shift in eigenfrequencies
of the mechanical structure, the authors propose the algorithmic implementation of the electrical behavior of the
impedance on a microcontroller. The digital approach enables real time updating of parameters associated with
the artificial electrical impedance. The problem of finding optimal parameters is addressed and an update law for
online tuning of parameters is introduced. The performance of the algorithm is evaluated on the mathematical
model of a Kirchhoff plate equipped with a piezoelectric patch shunted by a resistor.
This contribution is concerned with the hardware design of a structural health monitoring (SHM) system for
continuous delamination detection in carbon fiber reinforced polymer components. The component is equipped
with an integrated actuator array of eight piezoelectric patches which are driven by miniaturized high frequency
power amplifiers. The phased line array is capable of emitting directional guided Lamb waves with a frequency
of several hundreds of kilohertz and with user-selectable waveform pattern and directivity angle into the continuum.
The directivity of the Lamb wave depends on the phase difference between the individual actuator signals.
A special milling technique allows to create phased array stripes of arbitrary size and shape of the electrodes
with high precision and reduce the placing and time complexity. A laser scanning Doppler vibrometer is used to
visualize the propagation of the corresponding Lamb waves, as well as reflections which are caused by delamination
defects. The results of the measurements can be evaluated to characterize the damage and the material
properties. The hardware platform provides a portable system for the investigation of real world components,
e.g. aircraft CFRP structures.
This contribution deals with the implementation of a PC-controlled structural health monitoring system for continuous
damage detection. The system is implemented in a real size demonstrator component made of carbon fiber reinforced
polymer (CFRP). The component is equipped with an actuator array of piezoelectric patches which are driven by power
amplifiers. With the appropriate test signals elastic Lamb waves are emitted into the continuum in a specific direction.
Vibrometer measurements of reflections which are caused by delaminations make it possible to observe the size and
position of the defect areas.
A hybrid approach involving both analytical computations and measurement data is proposed for designing
optimal actuators for piezoelastic structures. The analytical part comprises the linear mathematical structure of
models of beams, plates or membranes which are appropriately described by mode shapes and modal paramters,
i.e. eigenfrequencies, modal gains and modal damping. Also, the governing differential equation for perfect compensation
of external loads due to piezoelectric actuation is applied. The measurement part relies on identification
of mode shapes and parameters under an external load using experimental modal analysis. The real-world data
is fed into the analyical part with the ultimate goal of achieving a match between the modal gains due to external
loading and piezoelectric actuation. The algorithm which can be extended to various mathematical models of
piezoelastic structures, is evaluated on a beam structure which is clamped at both ends.
Lightweight design is gaining more and more importance in the automotive industry. Engineers are trying hard to reduce
the increased weight of chassis due to safety and comfort issues.
This paper presents new achievements in the field of control design for smart structures, targeting at innovative
lightweight, high-performance and low-noise engineering constructions with integrated embedded systems technology:
The first part of the paper focuses on new developments in the field of low-cost, highly efficient smart structure power
electronics for piezoelectric elements. These elements will be integrated into automotive chassis, which are able to
measure any structure-borne disturbance such as vibrations.
The second part of the paper presents frontier research in the design of a high-performance control concept for smart
structure applications. This innovative control concept based on a nonlinear state observer design, targets at highly robust
and broadband suppression of structure-borne noise in terms of fast changing frequencies. The controller performance is
not only assessed with respect to stability and disturbance rejection but also with respect to technical feasibility and
implementation issues (required sample rate, rounding errors due to inappropriate data formats, latency, etc.).
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