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Exact modeling of power
and energy transduction for optimum design of structurally
integrated thin-film active sensors |
The project is to develop fundamental understanding and
predictive modeling of power and energy transduction in structurally integrated
thin-film active sensors. This transformative interdisciplinary research will
cross the boundaries of engineering disciplines and will create the foundation
for the mechatronics design for the development of energy-efficient SHM active
sensors and systems. A coordinated approach is proposed to understand the
fundamental aspects of ultrasonic power and energy transduction inside a hybrid
system consisting of active material sensors on a load-bearing structure in the
presence of multi-modal guided Lamb waves. |
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Self powered wireless sensor network for structural bridge health
prognosis |
This project is focused on the use of fused sensor data with multiple sensor
types to provide information related to the degradation state of the bridge
structure and its correlation to a global performance index. The acoustic
emission detection method will be combined with additional active sensor
(piezoelectric wafer active sensor) to strengthen the damage detection process
on the steel bridges. Though PWAS has been developed for thin wall aircraft
structures, its application and development for thick steel bridge structures is
novel. The structures will be scanned efficiently and cracks can be imaged
remotely. |
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Modeling, simulation and sensing of progressive damage at
multiple scales for performance prognosis in metallic and composite
aero structures |
An integrated modeling-simulation-sensing research
program for prognosis of composite and metallic components in aero-structures is
being developed. The research efforts combine (a) recent advances in structural
level modeling and simulation of load bearing capacity with cohesive zone
modeling for flaw initiation and propagation, (b) a new physics-based material
level modeling and predictive method for distributed damage accumulation in
composites, and (c) multi-level sensing for characterization of in-situ damage
detection in materials and structures. |
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Lamb-wave interaction
between piezoelectric wafer active sensor and host structure during
structure health monitoring |
Structural health monitoring (SHM) addresses problems of
aging structures, a major concern of the engineering community.
Recently, damage detection through Lamb waves has proven to be an
attractive option for SHM because it allows condition-based
maintenance inspection instead of schedule driven inspections.
Through Lamb wave detection, fewer numbers of sensor can be used to
monitor a structure and to actively investigate the health of a
structure system. One of the major limits to Lamb wave testing has
been the use of bulky permanent transducers integrated in the
structure. The introduction of piezoelectric wafer active sensors (PWAS)
had helped to overcome this issue. PWAS can be bonded on the surface
of the structure or embedded in it. The modeling and
characterization of Lamb waves generation and sensing using
surface-bonded/embedded piezoelectric wafer transducers for SHM has
received little attention, and often the various parameters involved
are chosen without mathematical foundation. Lamb wave detection
techniques using structurally integrated PWAS for SHM is still in
its formative years and little mathematical basis is provided for
the choice of the various testing parameters involved such as
transducer geometry, dimensions, location and materials, excitation
frequency, and bandwidth among others. Few efforts have been made
towards modeling Lamb-wave excitation and sensing using
surface-bonded/embedded transducers. The objective of this work is
to develop the concepts of the load transferred between actuator and
structure, trough the bonding layer at frequencies were the wave
modes have no more a linear displacement distribution across the
thickness and more then two modes are present. The load derived will
be uses to determine the PWAS tuning frequencies for an isotropic or
composite plate. The research will also investigate Lamb waves
scattering from flaws such as cracks through the boundary element
method, in order to understand the mode conversion from complicated
defect geometries. |
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Ferroelectric Thin-Film Active Sensor
Arrays for Structural Health Monitoring |
The research objective is to develop the fabrication and
optimum design of thin-film active sensor arrays for structural
health monitoring applications. This interdisciplinary research will
cross the engineering and science boundaries and will address the
problem in a coordinated approach focused on understanding the
fundamentals aspects of fabricating and using thin-film active
sensors on typical structural materials. |
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In-situ Damage Detection using Piezoelectric Wafer Active
Sensor Guided Waves Phased Array
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This research is focused on using piezoelectric
wafer active sensors (PWAS) to construct guided Lamb-wave phased
arrays for in-situ structural health monitoring. A unique feature of
this method, which makes it essentially different from the
traditional piezoelectric phased arrays, is that the PWAS phased
array performs virtual scanning by steering the beam through a
signal post processing procedure. Generic beamforming formulas for
using PWAS phased array are developed, followed with design,
beamforming simulation, and practical implementations of PWAS phased
arrays in 1-D and 2-D patterns. Advanced signal processing
techniques are introduced to improve the phased array performance
and detection capability. Proof-of-concept laboratory experiments
have successfully verified the potential of using PWAS phased arrays
for damage detection and structural health monitoring of plate and
shell-type thin-wall structures. |
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