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Damage Identification in Concrete using Impact Non-linear Reverberation Spectroscopy

Dahlén, Unn (2013) FMS820 20132
Mathematical Statistics
Abstract (Swedish)
Non-linear acoustic methods has shown increasing potential in the identication of
damage in brittle materials such as concrete. Commonly, these methods focus on
one or several resonance frequencies of the material and on the relative change in
resonance frequency and attenuation with strain amplitude which has been shown to
allow one to identify the extent of the material damage. However, current methods
are technically complicated and time consuming.
In this study, we use parametric methods to model the free vibration response
from concrete after an impact excitation. The technique is termed Impact Nonlinear
Reverberation Spectroscopy (INRS) and mainly focus on the strongest resonance
frequency in the vibration response. The... (More)
Non-linear acoustic methods has shown increasing potential in the identication of
damage in brittle materials such as concrete. Commonly, these methods focus on
one or several resonance frequencies of the material and on the relative change in
resonance frequency and attenuation with strain amplitude which has been shown to
allow one to identify the extent of the material damage. However, current methods
are technically complicated and time consuming.
In this study, we use parametric methods to model the free vibration response
from concrete after an impact excitation. The technique is termed Impact Nonlinear
Reverberation Spectroscopy (INRS) and mainly focus on the strongest resonance
frequency in the vibration response. The experiment is easily performed and
the measured vibration response contains several resonance frequencies. The signal
is shown to be well modelled as a discrete sum of time-varying amplitude polynomial
phase signals. Using this model, we propose a novel estimation algorithm based on
the higher order ambiguity function in combination with a relaxation-based least
squares tting procedure. We show that the strongest resonance frequency, in this
case the fundamental symmetric longitudinal mode, may be well modelled with an
exponential decaying amplitude with a polynomial attenuation and phase, both of
order three. The frequency and attenuation evolution with strain amplitude for the
strongest mode are then analysed and associated with the degree of damage.
In agreement with earlier studies, our result on real measurements show a frequency
decrease as well as an increase of attenuation as a function of the strain
amplitude. Furthermore, it is conrmed that a steeper slope of the amplitude dependence
on both frequency and attenuation can be associated with a higher degree
of damage. In addition, an analysis of the frequency dependence versus amplitude
indicates that the slope is dependent on the initial excitation amplitude. This is
not consistent with earlier studies and is probably due to a larger strain amplitude
used in the measurements, for which eects from slow dynamics becomes visible. (Less)
Please use this url to cite or link to this publication:
author
Dahlén, Unn
supervisor
organization
course
FMS820 20132
year
type
H2 - Master's Degree (Two Years)
subject
language
English
id
4192020
date added to LUP
2013-12-06 08:20:52
date last changed
2014-03-04 15:31:21
@misc{4192020,
  abstract     = {Non-linear acoustic methods has shown increasing potential in the identication of
damage in brittle materials such as concrete. Commonly, these methods focus on
one or several resonance frequencies of the material and on the relative change in
resonance frequency and attenuation with strain amplitude which has been shown to
allow one to identify the extent of the material damage. However, current methods
are technically complicated and time consuming.
In this study, we use parametric methods to model the free vibration response
from concrete after an impact excitation. The technique is termed Impact Nonlinear
Reverberation Spectroscopy (INRS) and mainly focus on the strongest resonance
frequency in the vibration response. The experiment is easily performed and
the measured vibration response contains several resonance frequencies. The signal
is shown to be well modelled as a discrete sum of time-varying amplitude polynomial
phase signals. Using this model, we propose a novel estimation algorithm based on
the higher order ambiguity function in combination with a relaxation-based least
squares tting procedure. We show that the strongest resonance frequency, in this
case the fundamental symmetric longitudinal mode, may be well modelled with an
exponential decaying amplitude with a polynomial attenuation and phase, both of
order three. The frequency and attenuation evolution with strain amplitude for the
strongest mode are then analysed and associated with the degree of damage.
In agreement with earlier studies, our result on real measurements show a frequency
decrease as well as an increase of attenuation as a function of the strain
amplitude. Furthermore, it is conrmed that a steeper slope of the amplitude dependence
on both frequency and attenuation can be associated with a higher degree
of damage. In addition, an analysis of the frequency dependence versus amplitude
indicates that the slope is dependent on the initial excitation amplitude. This is
not consistent with earlier studies and is probably due to a larger strain amplitude
used in the measurements, for which eects from slow dynamics becomes visible.},
  author       = {Dahlén, Unn},
  language     = {eng},
  note         = {Student Paper},
  title        = {Damage Identification in Concrete using Impact Non-linear Reverberation Spectroscopy},
  year         = {2013},
}