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1

Wykorzystanie geometrycznie ciągłych pomiarów światłowodowych (DFOS) w diagnostyce i monitoringu konstrukcji sprężonych

Piątek Bartosz, Howiacki Tomasz, Hanaczowski Marek, Siwowski Tomasz

Inżynieria i Budownictwo

|

2024

|

R. 80, nr 5

305--311

PL

Geometrycznie ciągłe pomiary światłowodowe (DFOS - distributed fiber optic sesnsing) to technologia pomiarowa, która w ostatnich latach przeżywa dynamiczny rozwój, i jest coraz powszechniej stosowana w wielu dziedzinach przemysłu, również w budownictwie. Dzięki możliwości wbudowania czujników już na etapie wytwarzania elementów z betonu sprężonego, można uzyskać istotne informacje na temat ich zachowania podczas betonowania, sprężania i dojrzewania betonu, a także pod wpływem reologii. Czujniki DFOS pozwalają na analizę zachowania konstrukcji pod obciążeniem i zmian zachodzących w czasie na poziomie dokładności nieosiągalnym dotychczas stosowanymi metodami. W artykule przedstawiono wyniki badań nad implementacją tej technologii w elementach strunobetonowych i kablobetonowych. Głównym celem badań było zweryfikowanie możliwości wykorzystania czujników DFOS do identyfikacji uszkodzeń (np. w postaci rys oraz pustek w kanałach kablowych) oraz monitorowania stanu odkształceń i przemieszczeń elementów z betonu sprężonego.

EN

Distributed Fiber Optic Sensing (DFOS) is a measurement technology that has experienced dynamic development in recent years and is increasingly used in various industries, including construction. By embedding sensors during the manufacturing stage of prestressed concrete elements, significant insights can be gained into their behavior during concrete pouring, prestressing, curing, and under rheological influences. DFOS sensors allow for the analysis of structural behavior under load and changes occurring over time with a level of accuracy previously unattainable with conventional methods. The paper presents research results on the implementation of this technology in pre-tensioned and post-tensioned elements. The main objective of the research was to verify the feasibility of using DFOS sensors to identify damages (e.g., cracks and simulated voids in cable ducts) and monitor the state of deformations and displacements in prestressed concrete elements.

2

Synthesis of the structural diagram with algorithms of the units of the on-board diagnostic system of induction motors of vehicles

Gubarevych Oleg, Melkonova Inna, Melkonov Hryhorii, Melnyk Olha, Miroshnykova Mariia

Diagnostyka

|

2024

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Vol. 25, No. 1

art. no. 2024109

EN

In this comprehensive study, the concept and structural diagram of the system for diagnostics of induction electric motors of vehicles with the development of algorithms for the operation of modular units for monitoring the state of the main structural elements are proposed. During the development of the diagnostic system, the peculiarities of the construction of diagnostic systems of rotating electric machines were investigated in the real conditions of their operation, and modern methods of current and vibration diagnostics were implemented. The work algorithms of each module are presented in the functional diagram of the general diagnostic system of and cover important defects of induction motors. The diagnostic system combines methods that use different diagnostic principles and criteria and are adapted for use in an embedded diagnostic system. The developed functional diagram of the diagnostic system can be used for practical implementation in physical form. The use of the proposed diagnostic system will make it possible to obtain continuous information about the state of both electrical and mechanical components of the induction motor when operating under load with a poor-quality power system in real operating conditions.

3

A novel method for identification of damage location in frame structures using a modal parameters-based indicator

Nashta Mina Roodgar, Taghipour Reza, Bozorgnasab Mohsen, Mirgolbabaei Hessam

Archives of Civil Engineering

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2022

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Vol. 68, nr 3

633--643

EN

Diverse strategies for identifying and finding the damages in structures have been continuously engaging to originators within the field. Due to the direct connection between the firmness, characteristic frequency, and mode shapes within the structure, the modular parameters may well be utilized for recognizing and finding the damages in structures. In current consider, a modern damage marker named Damage Localization Index (DLI) is applied, utilizing the mode shapes and their derivative. A finite element model of a frame with twenty and thirty components has been utilized, separately. The numerical model is confirmed based on experimental information. The indicator has been explored for the damaged components of a frame with one bay. The results have been compared with those of the well-known index CDF. To demonstrate the capability and exactness of the proposed method, the damages with low seriousness at different areas of the structures are explored. The results are investigated in noisy condition, considering 3% and 5% noise on modal data. The outcomes show the high level of accuracy of the proposed method for identifying the location of the damaged elements in frames.

4

A new index for damage identification in beam structures based on modal parameters

Taghipour Reza, Nashta Mina Roodgar, Bozorgnasab Moshen, Mirgolbabaei Hessam

Archive of Mechanical Engineering

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2021

|

LXVIII, nr 4

375--394

EN

The structural damages can lead to structural failure if they are not identified at early stages. Different methods for detecting and locating the damages in structures have been always appealing to designers in the field. Due to direct relation between the stiffness, natural frequency, and mode shapes in the structure, the modal parameters could be used for the purpose of detecting and locating the damages in structures. In the current study, a new damage indicator named “DLI” is proposed, using the mode shapes and their derivatives. A finite element model of a beam is used, and the numerical model is validated against experimental data. The proposed index is investigated for two beams with different support conditions and the results are compared with those of two well-known indices – MSEBI and CDF. To show the capability and accuracy of the proposed index, the damages with low severity at various locations of the structures containing the elements near the supports were investigated. The results under noisy conditions are investigated by considering 3% and 5% noise on modal data. The results show a high level of accuracy of the proposed index for identifying the location of the damaged elements in beams.

5

Wykrywanie uszkodzeń w konstrukcjach inżynierskich przy zastosowaniu metody dyskretnej transformacji falkowej

Knitter-Piątkowska Anna, Guminiak Michał

Przegląd Budowlany

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2020

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R. 91, nr 11

61--64

PL

Badania związane z wykrywaniem uszkodzeń i osłabień elementów konstrukcyjnych stanową bardzo ważny element kompleksowej analizy budowli inżynierskich. W analizie identyfikacji uszkodzeń wiodącą rolę odgrywają tzw. metody nieniszczące, które pozwalają dostatecznie precyzyjnie zlokalizować powstałe uszkodzenia. Prezentowana praca poświęcona jest zastosowaniu dyskretnej transformacji falkowej w procesie lokalizacji uszkodzeń konstrukcji. Dowolne uszkodzenie, np. w postaci lokalnego osłabienia sztywności konstrukcji (pęknięcia), jest przyczyną zaburzenia w rejestrowanym sygnale odpowiedzi - ugięciu, deformacji przekroju lub np. przyspieszeniu wybranego punktu konstrukcji. Zaburzenie sygnału jest na tyle małe, że dopiero jego przetworzenie za pomocą analizy falkowej pozwala zlokalizować miejsce uszkodzenia. Zaletą przedstawionej procedury jest wykorzystanie wyłącznie sygnału odpowiedzi rzeczywistej konstrukcji uszkodzonej. Przedstawiono krótki przegląd dotychczasowych analiz konstrukcji płytowych (płyt cienkich).

EN

Research related to the detection of damage and weakening of structural elements is a very important element of a comprehensive analysis of engineering structures. In the analysis of damage identification, the leading role is played by the so-called non-destructive methods that allow for sufficiently precise localization of the damage. The presented work is devoted to the application of the discrete wavelet transformation (DWT) to the process of identification and localization damages in structures. Any damage, e.g. in the form of a local weakening of the structure stiffness (cracks), causes disturbances in the recorded response signal - deflection, deformation of the cross-section or e.g. acceleration of a selected point of the structure. However, the signal disturbance is so small that only its processing by means of wavelet analysis allows to locate the damage site. The advantage of the presented procedure is the use of the response signal only of the real - damaged structure. The presented work is an overview of the results obtained so far. The slabs were analyzed as the basic surface structural systems that form the building structure.

6

Residual life estimation of structural beam using experimental and numerical modal analysis methods

Siva Gandam Anand, Ramakrishna Shinigam

Journal of Mechanical and Energy Engineering

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2020

|

Vol. 4, No 2

135--146

EN

A structural beam is a common element in many mechanical structures such as ship propeller shaft, crane boom, and aircraft wings. In the present paper experimental and numerical modal analysis are carried out for estimating the damage, geometric location of the damage, severity of damage and residual life of structural beam to prevent unexpected failures of mechanical structures. Experimental and numerical modal analysis results for healthy and cracked beam are compared for validation of numerical methodology used in the present paper. Experimental modal analysis is performed on both healthy and cracked beam with the help of impact hammer, acceleration sensor and FFT (Fast Fourier Transformer) analyzer associated with EDM (Engineering Data Management) software. Modal tests are conducted using impact method on selected locations of the entire healthy and cracked beam to find the first three natural frequencies, which are used to detect the presence of damage and geometric location of the damage. Three parametric studies are carried out to know the effect of crack depth, crack location and crack orientation on the natural frequencies of the cracked beam. Finally, the residual life of a healthy and cracked beam was estimated using Basiquin’s equation and finite element analysis software called ANSYS 18.1.

7

Application of 1-D and 2-D discrete wavelet transform to crack identification in statically and dynamically loaded plates

Knitter-Piatkowska Anna, Guminiak Michał

Engineering Transactions

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2020

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Vol. 68, iss. 2

137--157

EN

The paper presents the problem of damage detection in thin plates while considering the influence of static and dynamic characteristics, especially with regard to the modes of vibration as well as the excitation by static loads. The problem of Kirchhoff plate bending is described and solved by the Boundary Element Method (BEM). Rectangular plates supported on boundary or plates supported on boundary and resting on the internal columns are examined. A defect is introduced by the additional edges forming a crack in the plate domain. The analyses of static and dynamic structural responses are carried out with the use of Discrete Wavelet Transform (DWT). Signal decomposition according to the Mallat pyramid algorithm is applied. To obtain a more adequate input function subjected to DWT the white noise disturbing the signal is considered together with the structural response. In the dynamic experiments the plate undergoes vibrations similar to natural modes. The measured variables are static deflections and vertical displacement amplitudes. All of them are established at internal collocation points distributed alongside the line parallel to selected plate edge.

8

Modelling and parameter identification of steel–concrete composite beams in 3D rigid finite element method

Abramowicz Małgorzata, Berczyński Stefan, Wróblewski Tomasz

Archives of Civil and Mechanical Engineering

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2020

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Vol. 20, no. 4

47--70

EN

This study presents spatial vibration modelling of steel–concrete composite beams. Structures of this type are commonly used as elements of composite floors and primary carrying girders in bridge structures. Two-dimensional models used to date did not enable analysis of all eigenmodes, specifically torsional, flexural horizontal, and distortional. A discrete computational model was developed in the convention of the rigid finite element method, the so-called RFEM model. It was assumed that the concrete slab and the steel I-section would be modelled separately. This approach realistically reflects the actual performance of the connection, comprising studs connecting the concrete slab and the steel section. The model was used to analyse two steel–concrete composite beams with different connector spacings. The paper presents the results of experiments conducted on the two composite beams. Their dynamic characteristics, including frequency and vibration modes, were determined with impulse response methods. Based on experimental research, identification of connection parameters with substitute longitudinal moduli of elasticity of reinforced concrete was conducted. A comparison of experimental results with those calculated with the model confirmed their good agreement.

9

Magnetic memory inspection of an overhead crane girder : experimental verification

Kosoń-Schab Agnieszka, Smoczek Jarosław, Szpytko Janusz

Journal of KONES

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2019

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Vol. 26, No. 2

69--76

EN

The safety and efficiency of material handling systems involve periodical inspections and evaluation of transportation device technical conditions. That is particularly important in case of industrial cranes, since they are subjected to a large impact load and mechanical stresses acting on the crane's structure and equipment. The paper considers the possibility of a crane structure inspection using the metal magnetic memory (MMM) method. As an advanced non-destructive technique, this method can be employed for inspection of crane structure during operation, which leads to reduce the down time costs and increase the safety confidence in the monitoring process. The MMM technique is effective for early identification of the possible defect location and detecting the micro-damage in ferromagnetic structures through detecting the stress concentration areas. The basic principle of MMM method is the self-magnetic flux leakage signal that correlates with the degree of stress concentration. This method allows detecting early damage of ferromagnetic material through performing measurement in the earth magnetic field, without the use of a special magnetizing device. The paper presents the experimental results carried out on the double-girder overhead travelling crane with hoisting capacity 1000 kg. The influence of the load variation and duration time on the intensity of the self-magnetic flux leakage signal is analysed and discussed.

10

RMS-based damage detection in concrete beams: numerical simulations

Zima Beata, Kędra Rafał

Diagnostyka

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2019

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Vol. 20, No. 4

3--10

EN

Image-based damage detection methods using guided waves are well known and widely applied approaches in structural diagnostics. They are usually utilized in detection of surface damages or defects of plate-like structures. The article presents results of the study of applicability of imaging wave-based methods in detection in miniscule internal damage in the form of debonding. The investigations were carried out on numerical models of reinforced concrete beams with varying size of circumferentially oriented debonding between steel rod and concrete block. Maps created using root mean square of measured signals are presented. Moreover, the results were collected for two different excitation frequencies.

PL

Metody obrazowania uszkodzeń wykorzystujące propagację fal prowadzonych są dobrze znanym i powszechnie stosowanym narzędziem w diagnostyce konstrukcji. Zwykle są one wykorzystywane do wykrywania uszkodzeń powierzchniowych lub uszkodzeń obiektów płytowych. W artykule przedstawiono analizę możliwości wykorzystania metod obrazowania bazujących na propagacji fal prowadzonych w wykrywaniu niewielkich, wewnętrznych uszkodzeń w postaci rozwarstwienia. Analiza została przeprowadzona z użyciem modeli numerycznych belek żelbetowych z obwodowym rozwarstwieniem pomiędzy zbrojeniem a otuliną betonową charakteryzującym się różnymi rozmiarami. Po obliczeniu średniej kwadratowej dla zarejestrowanych sygnałów, wykonane zostały mapy. Ponadto, przedstawiono wyniki dla dwóch różnych częstotliwości wzbudzenia.

11

Effectiveness evaluation of the damage localization with a local spatial filtration under variable external conditions

Mendrok Krzysztof, Bocheńska Magda, Dworakowski Ziemowit

Diagnostyka

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2019

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Vol. 20, No. 1

55--61

EN

One of the biggest issues in damage detection and structural health monitoring is the influence of the ambient conditions changes on the operation of the algorithms. Very often the impact is similar to the one generated by fault and it results in false alarm. A lot of effort was put into trying to make these influences independent. The presented article shows the autonomous method, which allows to distinguish the influence of ambient temperature from damage on local spatial filtration. The idea is tested on both numerical and experimental data.

PL

Jednym z ważniejszych zagadnień w wykrywaniu uszkodzeń i układach monitorowania stanu obiektów jest wpływ zmian warunków zewnętrznych na działanie algorytmu. Bardzo często wspomniane oddziaływanie jest podobne do tego, które jest generowane przez uszkodzenie i może wywoływać fałszywe alarmy. Poświęcono dużo wysiłku w próby uniezależnienia tych wpływów. Prezentowany artykuł prezentuje autonomiczną metodę, która pozwala rozróżniać wpływy temperatury zewnętrznej od uszkodzenia na lokalną filtrację modalną. Pomysł był zweryfikowany przy pomocy danych numerycznych jak i eksperymentalnych.

12

Badania nieniszczące i monitoring elementów konstrukcji budowlanych w warunkach laboratoryjnych

Rucka M.

Badania Nieniszczące i Diagnostyka

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2018

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nr 3

36--41

PL

W artykule przedstawiono wyniki przykładowych badań diagnostycznych elementów konstrukcji inżynierskich w warunkach laboratoryjnych metodą propagacji fal mechanicznych. Testom poddano płytę stalową, zakładkowe połączenie klejone oraz czołowe połączenie śrubowe. Badania ukierunkowano na pozyskiwanie i rozpoznawanie wzorców uszkodzeń dla elementów i defektów o znanej geometrii oraz kontrolowanym sposobie zniszczenia. Przeprowadzone badania laboratoryjne umożliwiły przetestowanie efektywności analizowanych metod oraz wytypowanie wskaźników diagnostycznych.

EN

The paper presents the results of diagnostics of structural elements in laboratory conditions using the mechanical wave propagation method. The tests were carried out on a steel plate, an adhesive lap joint and a bolted flange joint. The research was focused on acquiring and recognizing damage patterns for elements with defects of known geometry and controlled failure. The laboratory tests made it possible to test the effectiveness of the analysed methods and to select diagnostic indicators.

13

An input–output damage detection method using static equivalent formulation of dynamic vibration

Mousavi M., Gandomi A. H.

Archives of Civil and Mechanical Engineering

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2018

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Vol. 18, no. 2

508--514

EN

In this study, a new damage detection method is developed which directly uses input–output data of a forced vibration of a structure. For this, the dynamic vibration formulation of an FE model has been integrated within the time domain of the vibration of the structure. Also, the static condensation scheme is used to reduce required measured degrees of freedom (DOF's). Hence, the main characteristic of the proposed method is that it just uses translational time history response of a structure at specified nodes corresponding to the finite element model of that structure. Also, the only required data from the original FE model of the structure is its stiffness matrix. To assess the capability of the proposed method in damage detection in beam type structures a cantilever beam is studied. Not only can the method locate damaged elements, but also the quantity of damage in every damaged element is computed successfully. Also, it has been shown that as the frequency of the applied load in simulated experiment approaches to the first natural frequency of the beam, the accuracy dwindles significantly. Hence, for obtaining more reliable results, the frequency of the applied load shall be far enough from the first natural frequency of the free vibration of the beam. The results demonstrate that the integrated displacements in specified nodes through the time of vibration carry enough information about damages in elements and the proposed method can be successfully used for damage detection in beam type structures.

14

Wykrywanie uszkodzeń konstrukcji na podstawie analizy zmian parametrów dynamicznych

Ziaja D., Miller B.

Zeszyty Naukowe. Inżynieria Środowiska / Uniwersytet Zielonogórski

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2017

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nr 166 (46)

75--84

PL

W artykule zaprezentowano ideę monitorowania stanu konstrukcji jako działania wspierającego ochronę środowiska. Przedstawiono, na przykładzie badań dwukondygnacyjnej ramy portalowej, wstępną propozycję procedury umożliwiającej detekcję uszkodzeń połączeń w badanej konstrukcji. Prezentowane w opracowaniu wnioski bazują na pomiarach przyspieszeń w wybranych punktach konstrukcji poddanej wzbudzeniu dynamicznemu. Jako narzędzie do analizy zmian parametrów dynamicznych układu wykorzystano jednowarstwowe, jednokierunkowe sztuczne sieci neuronowe.

EN

The article presents the idea of structural health monitoring as a supporting action to protect the environment. The preliminary proposal of a procedure enabling the damage detection of the joints is shown on the example of a two-storey portal frame. Conclusions, presented in the paper, based on the measurement of accelerations in selected points of structure, subjected to dynamic excitation. Single-layer, feed-forward artificial neural networks were used as a tool for the analysis of changes in the dynamic parameters.

15

Detection of material defects in reinforced concrete slab using active thermography

Różański L., Ziopaja K.

Measurement Automation Monitoring

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2017

|

Vol. 63, No. 3

82--85

EN

In order to validate the practical usage of passive and active infrared thermography for bridge inspection, a number of experimental studies have been conducted. Concrete slab of dimension of 60×60×10 cm made of concrete of strength class C35/45 was the object of research. Steel bars type B500SP with a diameter of ø10 and ø12 mm were used as reinforcement of analyzed slab. Four structure discontinuities imitating damages were implemented inside the slab. Using various methods of thermal excitation, the sensitivity of the slab response using infrared cameras was investigated. The paper presents the results of experiment and FEM simulation.

16

Effect of the multiple damages and temperature changes on the natural frequency

Mohammadi Esfarjani S., Salehi M., Ghassemi A.

Journal of Theoretical and Applied Mechanics

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2017

|

Vol. 55 nr 3

813—822

EN

Damage detection based on structural dynamic characteristics, such as natural frequencies and mode shapes, is an important area of research. Obtaining accurate structural dynamic characteristics is perhaps the most challenging aspect. In particular, changes in environmental temperature due to seasonal weather or radiation from sunshine leads to changes in the dynamic characteristics of structures. An important conclusion is that changes in the dynamic characteristics of a structure due to damage may be smaller than changes in the dynamic characteristics due to variations in temperature. Also, damage can affect the frequency response. This is the first study of evaluation of the effect of changes in temperature and multiple damages on natural frequency at the same time. In this paper, the simultaneous effect of the multiple defects and temperature on the natural frequencies of 6063 aluminum alloy beam are assessed numerically. ABAQUS finite element software is used for the numerical analysis. The present paper aims to evaluate the temperature effect and multiple damages on vibration responses. The variations in the frequency have been analysed in simulation by using an aluminum specimen and obtaining impedance signatures at temperatures ranging from −200◦C to 204◦C. The results show that an increase in temperature leads to a decrease in structural frequency, and that a decrease in temperature leads to an increase in structural frequency. The evaluation of the effect of multiple defects on natural frequency shows that when damages are created in the structure, there is a significant decrease in the natural frequency responses of the 6063 aluminum alloy beam. The results show that damage causes a decrease in the natural frequency of the structure. This study highlights the importance of applying simulation methods to the evaluation of the effect of changes in environmental temperature and multiple damages on the dynamic characteristics such as natural frequencies and mode shapes, especially at the same time.

17

Crack identification in plates using 1-D Discrete Wavelet Transform

Knitter-Piątkowska A., Guminiak M., Hloupis G.

Journal of Theoretical and Applied Mechanics

|

2017

|

Vol. 55 nr 2

481--496

EN

In the present work, the defect detection while using Discrete Wavelet Transform in rectangular plate structures is investigated. The plate bending is described by using the Boundary Element Method with boundary integral equations formulated in a modified simplified approach. The boundary elements of a constant type in a non-singular approach are implemented. Defects are introduced by additional edges forming slots or holes in relation to the basic plate domain. Estimation of the defect position is performed while using wavelet coefficients of curvature and deformation signals as well as a newly proposed moving variance estimator.

18

Localization of Sound Sources during Full Scale Fatigue Test of the Vertical Stabilizer with the Acoustic Holography Technique

Leski A., Szmidt M., Synaszko P.

Fatigue of Aircraft Structures

|

2017

|

Iss. 9

17--25

EN

An acoustic holography and its practical applications in engineering began to develop at the end of the 20th century. Currently, this technique is being commonly used to locate sound sources. This paper presents the use of an acoustic camera to locate sound sources during the Full Scale Fatigue Test of the MiG-29 stabilizer. During fatigue tests, the tested structure issues a series of sounds in the form of glitches, creaks or beats. These sounds are typical for a structure subjected to dynamic loading, but they can also be a source of diagnostic information about places of fatigue failures. The paper presents the results of measurements made during the fatigue test. Thanks to the analysis of the measurement results, it was possible to identify areas that are the basic source of sounds.

19

Wykrywanie uszkodzeń węzłów ramy stalowej z wykorzystaniem metody cyfrowej korelacji obrazu

Turoń B., Ziaja D., Miller B.

Czasopismo Inżynierii Lądowej, Środowiska i Architektury / Journal of Civil Engineering, Environment and Architecture

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2017

|

z. 64, nr 2/II

185--198

PL

W artykule pokazano możliwość zastosowania metody wizyjnej, jaką jest metoda cyfrowej korelacji obrazów (ang. Digital Image Correlation, DIC), do identyfikacji uszkodzeń w konstrukcjach budowlanych na przykładzie stalowej ramy dwukondygnacyjnej. W tym celu przeprowadzono pomiary przemieszczeń metodą DIC na wybranym fragmencie ramy obciążonej dynamicznie, dla różnych wariantów uszkodzenia wprowadzanego w połączeniach dolnego rygla ze słupami. Przeanalizowano otrzymane wartości przemieszczeń. Wyniki przeprowadzonego eksperymentu wskazują na duży potencjał w zastosowaniu metody DIC, jako alternatywnej metody pomiarowej, pozwalającej pozyskać dane wykorzystywane np. do detekcji uszkodzeń konstrukcji. W pracy pokazano również możliwość zastosowanie prezentowanego systemu do pomiarów szybkozmiennych.

EN

The paper presents the possibilities of applying the visual measurements (namely Digital Image Correlation method, DIC) in the damage identification of building structures on the example of a two-storey steel frame. For this purpose, displacement measurements were carried out on a selected fragment of the steel frame subjected to a dynamic load, for the various variants of the damage introduced in the column – lower spandrel beam joints of the frame. The obtained displacement values were analyzed. The results of this experiment indicate a high potential of the DIC application as an alternative measurement method, which allows to obtain data used for instance in the damage detection. The paper also shows the possibilities of applying the presented system for fast-change measurements.

20

Nondestructive Testing of Ceramic Hip Joint Implants with Laser Spot Thermography

Roemer J., Pieczonka L., Juszczyk M., Uhl T.

Archives of Metallurgy and Materials

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2017

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Vol. 62, iss. 4

2133--2139

EN

The paper presents an application of laser spot thermography for damage detection in ceramic samples with surface breaking cracks. The measurement technique is an active thermographic approach based on an external heat delivery to a test sample, by means of a laser pulse, and signal acquisition by an infrared camera. Damage detection is based on the analysis of surface temperature distribution near the exciting laser spot. The technique is nondestructive, non-contact and allows for full-field measurements. Surface breaking cracks are a very common type of damage in ceramic materials that are introduced in the manufacturing process or during the service period. This paper briefly discusses theoretical background of laser spot thermography, describes the experimental test rig and signal processing methods involved. Damage detection results obtained with laser spot thermography are compared with reference measurements obtained with vibrothermography. This is a different modality of active thermography, that has been previously proven effective for this type of damage. We demonstrate that both measurement techniques can be effectively used for damage detection and quality control applications of ceramic materials.