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Preface of the 38th International Conference and Exhibition "Defektoskopie 2008"
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Health Monitoring of Composite Aircraft Structure in the Course of Static Strength Testing J. Behal jr. 4 Aeronautical Research and Test Institute (VZLÚ) 11, Prague, Czech Republic Acoustic Emission (AE), signal processing, carbon fiber reinforced plastic (CFRP), structural health monitoring
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Full-scale strength test of airframe structure is performed due to safety requirement.
With application of advanced materials such as carbon fibre reinforced polymers to primary
structure, a new methodology of assessment the structure strength should be taken. There is
observed an acoustic emission as the structure is loaded especially close to its strength limit.
An efficiency of a strength test itself may be great improved by using structural health
monitoring system with on-line information about the material local loading related to its
limit. The experience is discussed in this study and processing of measured data is proposed.
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Detection of Disbonding of Composite Patch Airframe Repair by Acoustic Emission and Ultrasound J. Behal jr. 4, V. Makarov 2 Aeronautical Research and Test Institute (VZLÚ) 11, Prague, Czech Republic Acoustic Emission (AE), Ultrasonic Testing (UT), aerospace, periodic inspection, structural health monitoring, disbonding
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Application of composite patch is a modern technology of fatigue crack repairing in
aircraft industry. However, condition of bonded joint should be monitored in the service due
to exposition of the structure to temperature and humidity as well as cyclic loading.
For bonded joint inspection, an ultrasound method is used. Due to very thin layers of
structure material, a technique of reflected waves in the metal sheet was developed.
The experiment with technology test specimen was performed in the laboratory. The
fatigue life of the repair was simulated. Acoustic emission was monitored and the actual size
of disbonded area was analysed.
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Fuzzy lokalizace zdroj? akustické emise v cyklicky zat?ované letecké konstrukci Fuzzy Location of Acoustic Emission Sources in Cyclical Loaded Aircraft Structure Z. Převorovský 65, M. Blahacek 11 Czech Academy of Sciences (CAS) 113, Prague, Czech Republic Acoustic Emission (AE), localisation of damage, fuzzy logic, aerospace
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There are many experiments and measurements, where typical AE source location
error 100-1000 mm is clearly unacceptable. In suggested paper problem of AE
source location accuracy increasing will be discussed. Method based on fuzzy sets
theory principles will be demonstrated using AE data recorded during fatigue test of
small aircraft landing gear bracket.
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NDT-A Comparison Between Two Image Analysis Software Tools Z. Bolanca1 3, A. Hladnik2 4, I. Bolanca Mirkovic1 1Faculty of Graphic Arts; University of Zagreb 52, Zagreb, Croatia 2Faculty of Natural Sciences and Engineering; University of Ljubljana 99, Ljubljana, Slovenia
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Non-destructive testing method scanner based image analysis is used for dirt speck
measurement for the evaluation of prints deinkability in waste paper recycling
process. The measurement of dirt specks number and area and size classes
distribution in undenked and deinked pulps are presented. Two image analysis
software tools Spec*Scan, Apogee System and Proton in measurements are used.
As the investigation result, the influence of the printing technique, printing conditions,
toner and paper kinds on dirt specks number, area and size classes distribution in
both undeinked and deinked pulps has been established. The image analysis results
obtained for the software Proton are somewhat greater in regard to those obtained
for the software Apogee, but the trend is very similar.
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Mechanismy odpev?ovacích pochod? Mechanisms of Relaxation Processes J. Fiala 9, I. Schindler, F. Filu, T. Kubina Faculty of Metallurgical and Materials Engineering; VSB-Technical University of Ostrava 11, OSTRAVA, Czech Republic
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The driving force of relaxation processes, taking place in materials´ microstructure
and influencing thereby their mechanical behaviour, is the stored deformation energy
introduced into the body by (previous) technological operations. The relaxation
processes apply in both manufacture and service degradation. Monitoring the course
of relaxation processes allows to increase the reliability of the prediction of the
residual service life of the constructional units. The mechanisms of the relaxation
processes are diverse in different materials. In the present contribution, an account is
given on a complex kinetic analysis of relaxation processes in three different steels.
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Vyuití nelineární ultrazvukové spektroskopie pro zdokonalení spektrální analýzy impact-echo signálu Utilization of Nonlinear Ultrasound Spectroscopy for Improvement of Spectral Analysis of the Impact-Echo Signal K. Hajek1 14, J. Sikula2 18 1Dpt. of Electrical Engineering, FVT; University of Defence in Brno (Univerzita obrany) 16, Brno, Czech Republic 2Brno University of Technology (BUT) 225, Brno, Czech Republic
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The classical impact echo signal analysis grows to be standard NDT method.
Nevertheless it doesn?t derive all information about faults in tested solid from the
recorded signal. If we consider that most of failures have nonlinear properties, we
can use the knowledge about nonlinear ultrasound spectroscopy for improving of
spectral analysis of impact/echo signal. This paper shows some ways and methods
inclusive first experiments.
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Improving the Ultrasonic Nondestructive Evaluation Signals by Iterative Wiener Filtering M. Hajian , F. Honarvar 26 , H. Abrishami-moghaddam aFaculty of Mechanical Engineering, NDE Lab bFaculty of Mechanical Engineering,NDE Lab ; K. N. Toosi University of Technology (KNT) 27, Tehran, Iran Ultrasonic Testing (UT), A-Scan, ultrasonic signals, Wiener filter, signal processing, iterative
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Signals measured in ultrasonic nondestructive evaluation (NDE) of materials are
masked by the characteristics of the measuring instruments, the propagation paths taken by
the ultrasonic waves, and noise originating from various sources, including the electrical
noise. Due to the band-limited characteristics of ultrasonic transducers, the received echoes
are degraded by the transducer impulse response and show a relatively low time resolution. In
order to remove the transducer impulse response in the presence of noise, deconvolution
techniques are usually implemented. One of these deconvolution techniques is the Wiener
filter. Implementation of an optimal Wiener filter requires estimation of the statistical
distributions of both the desired signal and the noise present in this signal. In practical
applications, this information is not readily available and needs to be somehow estimated. In
this paper an iterative algorithm is proposed for estimating the power spectral density of the
desired signal. This method uses the signal processed by the Wiener filter as an improved
signal to update the power spectral density estimates. The results obtained from synthetic data
indicate that the proposed method outperforms the conventional Wiener filter and could
significantly improve the time resolution of the ultrasonic signals.
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Non-Destructive Evaluation of the Concrete Floor Quality Using Impulse Response S?Mash And Impact-Echo Methods J. Hoła 26, K. Schabowicz 30 , L. Sadowski 12 Institute of Building Engineering; Wroclaw University of Science and Technology (WUST)) 72, Wrocław, Poland NDT-wide, Ultrasonic Testing (UT), impact-echo, signal analysis, concrete, in-situ, crack, surface cracks, Poland, quality control
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New Design and Algorithm for an Ultrasonic Propagation Imaging System C. Chia1 4, J. Lee1 14, J. Park2, C. Yun1, J. Kim3 1Department of Aerospace Engineering; Chonbuk National University (CBNU) 18, Jeonju, South Korea 2Structures & Materials Department; Korea Aerospace Research Institute 2, Daejeon, South Korea 3Department of Aeronautical Technology ; Agency for Defense Development, Daejeon, South Korea
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Laser-based ultrasonic sensing generally requires the probe to have a fixed focal length or to be
contact. On the other hand, such a requirement is not essential in laser-based ultrasonic
generation. Based on this point, we designed a pulsed laser-based ultrasonic propagation imaging
(UPI) system which included developments of a tilting mirror system (TMS) for rapid ultrasonic
scanning of target and an in-line filter for real-time band-pass filtering capable of ultrasonic mode
selection. For the novel UPI algorithm as well as the UPI system, 1D-temporal averaging, 2Dspatial
averaging, and 3D-data structure building algorithms were developed for clearer results,
hence higher damage detectability. The imaging results on a flat stainless steel plate were
presented in movie and snapshot formats which showed the propagation of ultrasound visible as a
concentric wavefield emerging from an installed ultrasonic sensor. An open hole of diameter 1
mm on the plate was indicated by the scattering wavefields. Even if the damage size was
comparatively small, the result was clear enough for non-experts on ultrasonics not to overlook it.
The results showed that this UPI system is robust and independent of focal length and reference
data requirement. Therefore, the UPI system will be able to a versatile tool for on-site automatic
nondestructive testing for many applications such as power plant structures, infrastructures and
transportation structures.
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Optimalizace volby signálových parametr? pro rozpoznávání zdroj? akustické emise Optimized Number of Signal Features for Identification of AE Sources M. Chlada 32, Z. Převorovský 65 Czech Academy of Sciences (CAS) 113, Prague, Czech Republic Acoustic Emission (AE), Feature Extraction, source recognition, neural network, signature analysis CS
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Hot Target Inspection Based on Fiber Acoustic Wave Pzt Sensor and Qswitched Pulsed Laser S. Jang1 , C. Chia1 4, J. Lee1 14, S. Lee2 16, D. Kang3 2 1Department of Aerospace Engineering; Chonbuk National University (CBNU) 18, Jeonju, South Korea 2Safety Metrology Group; Korea Research Institute of Standards and Science (KRISS) 63, Daejeon, South Korea 3Korea Railroad Research Institute 7, Daejeon, South Korea
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Direct attachment of piezoelectric transducers on hot targets raise formidable
challenges as piezoelectric materials will lose their piezoelectric characteristic at elevated
temperature due to Curie temperature limitation. In this paper, an attempt was made to build
an integrated probe for hot target which enables to alleviate innovatively the Curie
temperature limitation. In addition, the problem of sensor debonding due to the mismatch of
coefficient of thermal expansion between the target, sensor and bonding material was
experimentally illustrated. A fiber acoustic wave PZT (FAWPZT) sensor was then used to
solve the debonding problem and Curie temperature limitation. The FAWPZT sensor was
made from a stainless steel fiber, with one end welded on the hot target and the other end
bonded with a PZT sensor. An ultrasonic propagation imaging (UPI) system consisted of a Qswitched
Nd-YAG pulsed laser (QPL) with 20 Hz-repetition rate and a motorized tilting
mirror system (TMS) for rapid scanning of target was successfully applied on a
stainless steel target plate at a temperature 5005001mm3 of about 150oC. Although the
target temperature stood at 150oC, the temperature of the PZT part in the FAWPZT remained
almost room temperature. The UPI system scanned a area of interest on the
target enclosed with an artificial 2 mm-open crack. The result was presented in the form of
ultrasound wave propagation movie visible as a concentric wavefield emerging from the
sensing point. The damage was detected and visible as scattered wave emerging from the
location of damage. Overall, the result confirmed that the FAWPZT sensor combined with a
QPL is an economic technology with good potential for implementation in hot target
integrated structural health monitoring.
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Nondestructive Evaluation of Wood Plastic Composites Using Ultrasonic Technique S. Kazemi Najafi1 , G. Ebrahimi2 2, S. Behjati1 1Department of Wood and Paper Science and Technology; Tarbiat Modares University, Tehran, Iran 2Wood and Paper Industry Faculty of Natural Resources; University of Tehran 7, Tehran, Iran
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Wood Plastic Composites (WPCs) are a relatively new family of composite materials which
are becoming more and more commonplace by the development of new production
techniques and processing equipment. So it is necessary to develop an effective
nondestructive technique to evaluate these products. Among the nondestructive techniques,
ultrasonic method is often used for nondestructive evaluation of composites. For WPC,
firstly need to study ultrasonic wave propagation in such composites. For this reason, in this
research the through transmission ultrasonic method was used to measure the ultrasonic
wave velocity in WPC using a commercial ultrasonic tester (Sylvatest Duo) of 16 kHz
longitudinal waves. Wood flour/E-glass fiber hybrid polypropylene composites were
manufactured in a counter-rotating twin-screw extruder. The effect of wood flour content,
compatibilizers(MAPP), glass fiber contents and specimen length on ultrasonic velocity
were investigated. Also ultrasonic wave velocities were measured in wood and
polypropylene and were compared to ultrasonic velocity in WPCs.
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Lokalizace trhlin vznikajících p?i mechanickém zat?ování pevných látek Localization of Cracks Arising from Mechanical Loading of Solids P. Koktavý 5, B. Koktavý 5, L. Grmela 2, V. Burdej aFaculty of elektrotechnik and komunikation technology bFakulta stavební; Brno University of Technology (BUT) 225, Brno, Czech Republic Acoustic Emission (AE), localisation of damage, Electromagnetic Testing (ET), Electromagnetic emission (EME)
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Simultaneous measurement of electromagnetic (EME) and acoustic (AE) emission signals
resulting from mechanical loading of solids can be used to localize the arising cracks. In the
2D case, the localization methods are usually based on identifying intersection points of the
circles drawn around the AE sensors (provided the time of the crack generation is known
from the EME signal measurement) or hyperbolas, whose foci are situated in the AE sensors
(when only AE signals are measured). When these methods are applied, the mechanical wave
propagation velocity in the material under investigation must be known. However, if an
excessive number of AE sensors is used, the different circle or hyperbola intersection points
are not identical. In fact, these intersection points are only marking the boundaries of the
region of probable crack generation. The information provided for the point in question in this
way is not unambiguous. Therefore, to support the arising crack localization efforts, a new
localization method has been designed, which is based on a conveniently selected error
function being defined throughout the specimen bulk. The value of this function at any
selected point of the specimen expresses, based on the signal measurement, the suitability of
the particular point to be identified with the crack generation point. The point at which the
error function value reaches a minimum is considered to be identical with the crack
generation point. When applying this method, the mechanical wave propagation velocity in
the solid need not be known. On the contrary, this method can be applied to the determination
of the wave propagation velocity. Several error function types have been designed. The
applicability of these methods has been verified experimentally, using a dedicated specimen
which makes it possible to simulate the crack generation at an exactly specified point.
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Provozní kontroly heterogenních svar? ultrazvukovou metodou phased array v JE Temelín In-Service Inspection of Dissimilar Welds by the Phased Array Ultrasonic Method at Temelin NPP J. Kolar 3 CEZ, a.s., JE, Temelín 3, Temelín, Czech Republic
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In the contribution substantial changes are being presented for the inspection of
circumferential dissimilar welds of safety important piping systems at Temelin NPP.
During the year 2007 was carried out the usability verification of ultrasonic testing by
the Phased Array method. For the verification were used the test block with artificial
defects for dissimilar welds of emergency core cooling piping which injects the boric
acid solution to the main circuit pipeline.
All ultrasonic examinations were carried-out manually only with encoder for
detection of defects circumferential position and measurement of defects length,
because there is not possible to use any manipulator due to a bad accessibility to the
inspection area.
Results of the verification confirmed the Phased Array method of ultrasonic
testing is suitable for chosen inspection areas and since this year were phased array
applications permanently introduced to the in-service inspections program of Temelin
NPP.
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Bridge Structure Diagnostics Using the Acoustic Emission Method M. Kořenská1 44, J. Stryk2 6, L. Pazder1 44, P. Vyroubal1 6 1aFaculty of Civil Engineering, Department of Physics bFac. of Civil Eng., Dept. of Physics; Brno University of Technology (BUT) 225, Brno, Czech Republic 2Dept. of Infrastructure; Transport Research Centre 8, Brno, Czech Republic Acoustic Emission (AE), acoustic emission sensor, Inspection, civil engineering, bridge, reinforced concrete, corrosion testing
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Stability of building structures is one of very important issues in the field of nondestructive
defectoscopy. Taking into account the fact that most of concrete and
reinforced concrete structures were created in the first half of last century, it is
evident that a search for new and simple defectoscopic methods, allowing the
researchers to determine the integrity of these building structures or their parts, is of
primary importance. It is also essential to develop and/or refine the methods
designed to estimate the lifetime of building structures. The current methods of nondestructive
testing of building materials are suitable for the defectoscopy of
homogeneous materials and simple-shaped bodies. Their application to
inhomogeneous building materials is difficult in the case of small-sized cracks and
defects uniformly distributed throughout the specimen.
This is why non-destructive diagnostic methods (NDT) are acquiring growing
importance, helping the researchers to evaluate properly the condition of a bridge
and decide upon the most convenient method maintenance, repair or refurbishment
of the bridge in question or its parts and schedule them accordingly. Reconstructions
of motorway bridges are frequently accompanied with long-time restrictions of the
number of motorway lanes, which result in considerable delays and consequent
financial losses of the motorway users. If the application of NDT methods contribute
to optimizing the bridge repair interventions and their scheduling in conformity with
safety rules, then the costs of researching new NDT methods are fully justified.
One of the methods, which is recognized worldwide as the most promising for the
mentioned purposes, is the acoustic emission (AE) method. By contrast to most other
NDT methods, AE is a comprehensible method, allowing both one-shot examination
and long-term monitoring of the condition of the structure under consideration or its
selected parts. The present paper deals with the use of the AE method from the
viewpoint of its application to diagnosing the bridge structure reinforcement corrosion
and its consequences.
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Impedan?ní spektroskopie betonu s p?echodovou vrstvou sodného vodního skla I. Kusák 19, M. Luhák, L. Pazder 44, P. Schauer Faculty of Civil Engineering, Department of Physics; Brno University of Technology (BUT) 225, Brno, Czech Republic Acoustic Emission (AE), Visual and Optical Testing (VT/OT), spectroscopy, spectroscopy, water glass, permittivity, materials characterization
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The impedance spectroscopy method, one of the non-destructive testing
methods, has been applied to characterize concrete specimens and track the changes in the
frequency spectra before and after a sodium water-glass layer has been spread over its
surface. Variations in the tan (f) and Im Z(f) or Re Z(f) plots have been observed and the
specimen quality has been described using the predominant loss kind in the material in
question. Our results appear to indicate a possible correlation between the n-factor obtained
by this method and the specimen porosity. They can also indicate electric conductivity
variances in the frequency spectra of the material under investigation.
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Sign and Arrival Time Determination of Acoustic Emission Signals by Means of High-Order Statistic Approach T. Lokajicek 12, K. Klíma 2 Institute of Geology; Czech Academy of Sciences (CAS) 113, Prague, Czech Republic
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The precise and reliable determination of the first arrival of acoustic (ultrasonic) emission
(AE) signals (or seismic signals) recorded by multichannel systems is one of the fundamental
problems in nondestructive testing, rock mechanics and seismology. The article describes an
approach based on high-order statistics (HOS), which is able to carry out precise arrival time
determination and sign of the first arrival without human intervention. The algorithm use
changes of HOS parameters as skewness, kurtosis and empirical parameters based on statistic
moments of fifth and sixth order of individual AE signals.
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On the Diagnosis of Hurdis Ceiling Slabs Using Non-Linear Ultrasonic Spectroscopy Methods M. Manychova 15 Faculty of Civil Engineering, Department of Building Structures; Brno University of Technology (BUT) 225, Brno, Czech Republic Ultrasonic Testing (UT), non linear acoustics, frequency analysis, Testing, detection, Non Linear Ultrasonic Spectroscopy, civil engineering, ceramic, defect, crack detection
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The paper is focused to possibility of utilization of the non-linear phenomena arising
in connection with the propagation of ultrasonic waves in solids to diagnostic ceiling
slabs Hurdis. Breakdowns of ceiling structures made of Hurdis slabs have be
problem in building industry of today. Since the early 90? several thousands of
buildings with these ceilings were constructed. As a result of this failures may appear
again in the following years. Therefore it is necessary to develop and check suitable
methods enabling the testing of endangered ceiling structures and considering their
static reliability. Non-lineary ultrasonic spectroscopy methods are based on the fact
that a crack induced non-linearity makes an extremely sensitive material impairment
indicator. Due to the presence of defects, the atom potential energy ceases to be
exactly harmonic. Second and third harmonic frequencies signals arise. The intact
material region generates almost zero non-linearity. Another important benefit results
from the higher sensitivity in relation to the defect size and the system immunity to
the measuring of smaller signal reflections, as the sample edges lack any non-linear
properties and consequently, there are no narrow-band signals arising from these
reflections.
Non-linear ultrasound spectroscopy methods due to their supposed higher sensibility
and more exact characterization of material quality and reliability appear as
perspective for both aims.
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Ov??ování pouití UT phased array na svarových spojích potrubí DN200 P. Mares 12, V. Plajt, J. Pergler Nuclear Research Institute (NRI, UJV - Rez) 14, ReZ, Czech Republic Ultrasonic Testing (UT), phased array, pipeline girth welds CS
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