Change search
Link to record
Permanent link

Direct link
BETA
Publications (10 of 20) Show all publications
Broberg, P. & Runnemalm, A. (2016). Analysis algorithm for surface crack detection by thermography with UV light excitation. In: Kaczmarek, M. & Bujnowski, A. (Ed.), Quantitative InfraRed Thermography 2016: Abstracts. Paper presented at 13th Quantitative InfraRed Thermography, Gdańsk, Poland, July 4-8, 2016 (pp. 144-149). Gdańsk, Poland: Publishing Gdańsk University of Technology
Open this publication in new window or tab >>Analysis algorithm for surface crack detection by thermography with UV light excitation
2016 (English)In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, p. 144-149Conference paper, Published paper (Refereed)
Abstract [en]

Surface crack defects can be detected by IR thermograpgy due to the high absorption of energy within the crack cavity. It is often difficult to detect the defect in the raw data, since the signal easily drowns in the background. It is therefore important to have good analysis algorithms that can reduce the background and enhance the defect. Here an analysis algorithm is presented which significantly increases the signal to noise ratio of the defects and reduces the image sequence from the camera to one image.

Place, publisher, year, edition, pages
Gdańsk, Poland: Publishing Gdańsk University of Technology, 2016
National Category
Production Engineering, Human Work Science and Ergonomics Manufacturing, Surface and Joining Technology Metallurgy and Metallic Materials
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-10130 (URN)
Conference
13th Quantitative InfraRed Thermography, Gdańsk, Poland, July 4-8, 2016
Available from: 2016-11-10 Created: 2016-11-10 Last updated: 2019-03-15Bibliographically approved
Runnemalm, A., Broberg, P., Garcia de la Yedra, A., Fuente, R., Beizama, A. M., Fernandez, E., . . . Henriksson, P. (2016). Automated inspection of welds with limited access by use of active thermography with laser line excitation. In: : . Paper presented at 19th World Conference on Non-Destructive Testing 2016. , Article ID 19664.
Open this publication in new window or tab >>Automated inspection of welds with limited access by use of active thermography with laser line excitation
Show others...
2016 (English)Conference paper, Published paper (Other academic)
Abstract [en]

Inspection of welds for detecting surface breaking defects is traditionally performed by using NDT methods such as Fluorescent Penetrant Inspection, Visual Inspection or Eddy Current. All those well-known techniques have drawbacks, as they need access to the surface, either for preparation with e.g. liquids or for using contact probes. Traditional methods also require a skilled operator to carry out the inspection, and moreover to analyse the obtained results. Furthermore, for the inspection of welds with limited access, the use of those traditional methods is even more complex, resulting in increased inspection time and reduced detection capability or in worst case, areas impossible to inspect. Therefore, the development of a fully automated non-contact method overcoming these limitations is desired. ;Active thermography is a novel NDT technique for weld inspection. The method has shown promising results for replacing traditional techniques when it comes to detection of surface breaking defects in metals. The method make use of an excitation source in order to heat the sample in a controlled manner during the test, and an infrared thermal camera for recordings of the thermal evolution. ;In this work, an automated solution developed and demonstrated for inspection of welds in a jet-engine component with limited access is presented. The NDT system is mounted on an industrial robot, making it possible to automatic scan the inspected area. The system consists of a, continuous laser-line excitation source together with a FLIR SC 655 microbolometer thermographic camera. In order to access limited areas, two polished aluminium mirrors have been used for both infrared radiation monitoring and laser excitation respectively. A solution for automatic analysing, defect detection and sizing is also included and presented.

Keywords
Welding, surface, inspection
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology; ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-10560 (URN)
Conference
19th World Conference on Non-Destructive Testing 2016
Available from: 2017-01-12 Created: 2017-01-12 Last updated: 2018-08-12Bibliographically approved
Sikström, F., Runnemalm, A., Broberg, P., Nilsen, M. & Svenman, E. (2016). Evaluation of non-contact methods for joint tracking in a laser beam welding application. In: The 7th International Swedish Production Symposium, Conference Proceedings: 25th – 27th of October 2016. Paper presented at 7th Swedish Production Symposium, Lund, Sweden, October 25-27, 2016 (pp. 1-6). Lund: Swedish Production Symposium
Open this publication in new window or tab >>Evaluation of non-contact methods for joint tracking in a laser beam welding application
Show others...
2016 (English)In: The 7th International Swedish Production Symposium, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Symposium , 2016, p. 1-6Conference paper, Published paper (Other academic)
Abstract [en]

The use of automated laser welding is a key enabler for resource efficient manufacturing in several industrial sectors. One disadvantage with laser welding is the narrow tolerance requirements in the joint fit-up. This is the main reason for the importance of joint tracking systems. This paper describes anevaluation of four non-contact measurement methods to measure the position, gap width and misalignment between superalloy plates. The evaluation was carried out for increased knowledge about the possibilities and limitations with the different methods. The methods are vision-, laser-line-,thermography- and inductive probe systems which are compared in an experimental setup representing a relevant industrial application. Vision is based on a CMOS camera, where the image information is used directly for the measurements. Laser-line is based on triangulation between a camera and a projected laserline. Thermography detects the heat increase in the gap width due to external heat excitation. Inductive probe uses two eddy current coils, and by a complex response method possibilities to narrow gap measurement is achieved. The results, evaluated by comparing the data from the different systems, clearly highlights possibilities and limitations with respective method and serves as a guide in the development of laser beam welding.

Place, publisher, year, edition, pages
Lund: Swedish Production Symposium, 2016
Keywords
Joint tracking, Gap width, Misalignment, Inductive coil, Thermography, Laser line, Vision sensor
National Category
Manufacturing, Surface and Joining Technology
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-10147 (URN)
Conference
7th Swedish Production Symposium, Lund, Sweden, October 25-27, 2016
Note

Ingår i lic.uppsats

Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2019-05-10Bibliographically approved
Broberg, P., Sjödahl, M. & Runnemalm, A. (2015). Comparison of NDT-methods for automatic inspection of weld defects. International journal of materials & product technology, 50(1), 1-21
Open this publication in new window or tab >>Comparison of NDT-methods for automatic inspection of weld defects
2015 (English)In: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 50, no 1, p. 1-21Article in journal (Refereed) Published
Abstract [en]

The purpose of this study is to investigate different NDT-methods for weld inspection in an objective manner. Test objects are produced with known variation of flaws: internal pores, surface and internal cracks, toe radius and weld depth. The NDT-methods compared are: phased array ultrasound, radiography, eddy current, thermography and shearography. The results show that radiography is the better method for volumetric defects in thin plates while ultrasound is better for flat defects and thicker, non-flat plates. Thermography was shown to have a good ability of detecting surface defects. A combination of ultrasound and thermography results in a detection of all the non-geometrical defects investigated in this study.

Keywords
non-destructive testing, NDT, weld defects, automatic inspection
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-3113 (URN)10.1504/IJMPT.2015.066863 (DOI)000352133300001 ()2-s2.0-84921311226 (Scopus ID)
Projects
ANDTE
Available from: 2011-01-27 Created: 2011-01-27 Last updated: 2017-12-11Bibliographically approved
Fuente, R., García de la Yedra, A., Beizama, A. M., Fernández, E., Gorostegui Colinas, E., Echeverria, A., . . . Henrikson, P. (2015). Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography. In: Proceedings 7th International Symposium on NDT in Aerospace: . Paper presented at 7th International Symposium on NDT in Aerospace,16 – 18 November 2015 Bremen, Germany (pp. 1-8). Berlin
Open this publication in new window or tab >>Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography
Show others...
2015 (English)In: Proceedings 7th International Symposium on NDT in Aerospace, Berlin, 2015, p. 1-8Conference paper, Published paper (Refereed)
Abstract [en]

Weld inspection for surface breaking defects detection has been traditionally performed by using NDT methods such as Fluorescent PenetrantInspection (FPI), Visual Inspection (VI) or Eddy Currents (EC). All those well known techniques have as common drawback the need of skilled operator intervention in order to analyse obtained results. In the specific case of inspection of welds with limited access, the application of those traditional methods is even more complex, thus increasing inspection time and reducing the defect detection capability. Therefore, the development of a fully automated non-contact method overcoming these limitations is desired. Active thermography (IRT) represents one of the most promising techniques for replacing traditional techniques for surface breaking defect detection in welds.This technique makes use of an excitation source in order to heat the sample undertest and an infrared camera for thermal evolution monitoring. With the combination of these excitation-monitoring techniques, heterogeneities in the heat flow caused bysurface breaking cracks can be detected. In this work, a robotic solution was developed and demonstrated for the inspection of welds with real cracks in a representative environment with limited access. The system consists of a continuous laser-line excitation source together with a FLIR SC 655 micro bolometer thermographic camera. In order to access limited areas, two different aluminium polished mirrors have been used for bothinfrared radiation monitoring and laser excitation respectively. The inspection results, analysis and comparison with traditional methods will be shown.

Place, publisher, year, edition, pages
Berlin: , 2015
Keywords
Weldning, automated systems
National Category
Aerospace Engineering Production Engineering, Human Work Science and Ergonomics
Research subject
Production Technology
Identifiers
urn:nbn:se:hv:diva-9283 (URN)
Conference
7th International Symposium on NDT in Aerospace,16 – 18 November 2015 Bremen, Germany
Available from: 2016-04-04 Created: 2016-04-04 Last updated: 2018-08-12
Broberg, P. (2014). Analysis method for pulsed thermography based on an analytical solution of the heat equation.
Open this publication in new window or tab >>Analysis method for pulsed thermography based on an analytical solution of the heat equation
2014 (English)Article in journal (Refereed) Submitted
Abstract [en]

An analytical solution to the heat equation is presented, using a simplified physical model of pulsed thermography. This solution was compared to experimental data and showed good correlation, with r=0.97. An analysis method for sizing and determining the depth of a defect was developed using this analytical solution. The shape of the defect was estimated using deconvolution. Results from thermography tests on flat bottom holes show the possibilities of the method to determine the size, shape and depth of the defect, if the physical properties of the material are known.

Keywords
Pulsed thermography; defect shape reconstruction; analytic solution; deconvolution
National Category
Mechanical Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-6694 (URN)
Note

Ingår i författarens avhandling.

Available from: 2014-09-17 Created: 2014-09-17 Last updated: 2016-02-08Bibliographically approved
Broberg, P. (2014). Analytic model for pulsed thermography of subsurface defects. In: Archives QIRT 2014: Documents and sessions presented during the 12nd conference QIRT (Bordeaux, France). Paper presented at Conference QIRT 2014 (Bordeaux, France), 7-11 July 2014 (pp. 1-5). QIRT
Open this publication in new window or tab >>Analytic model for pulsed thermography of subsurface defects
2014 (English)In: Archives QIRT 2014: Documents and sessions presented during the 12nd conference QIRT (Bordeaux, France), QIRT , 2014, p. 1-5Conference paper, Published paper (Refereed)
Abstract [en]

An analytic solution to the heat equation is used to model the response of subsurface defects in pulsed thermography. The model is compared to measurement data and shows good agreement, both in spatial and temporaldomain. The capability of the model is then demonstrated by calculating the response of arbitrary defects at different depth. This model, even though simplified, can prove useful due to good accuracy and low computational time forcomparing analysis methods and for evaluating a thermography method on a new material or new type of defect.

Place, publisher, year, edition, pages
QIRT, 2014
Keywords
Thermography, surface, defects
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-7276 (URN)
Conference
Conference QIRT 2014 (Bordeaux, France), 7-11 July 2014
Available from: 2015-01-12 Created: 2015-01-12 Last updated: 2018-08-12Bibliographically approved
Runnemalm, A., Broberg, P., Fernandez, E., Garcia de la Yedra, A., Henrikson, P. & Thorpe, N. (2014). Automatic thermography inspection of welded components with limited access. In: Proceedings of 6th International Symposium on NDT in Aerospace, 12-14th November 2014, Madrid, Spain: . Paper presented at 6th International Symposium on NDT in Aerospace, 12-14th November 2014, Madrid, Spain (pp. 1-10).
Open this publication in new window or tab >>Automatic thermography inspection of welded components with limited access
Show others...
2014 (English)In: Proceedings of 6th International Symposium on NDT in Aerospace, 12-14th November 2014, Madrid, Spain, 2014, p. 1-10Conference paper, Published paper (Refereed)
Abstract [en]

Inspection of welds with limited access puts specific requirement on the NDT-method to be used. A non-contact method without the need for special surface preparation is preferable for fast and cost efficient inspection and with the possibility of automation. Infrared thermography has been known for quite a long time and is today mainly used for NDT inspection of composite structures. The technique is based on registering the heat conduction of the material of the surface of the structure. The method requires some kind of excitation resulting in a change of heat locally in the inspected area. In the study presented in this paper, different excitation methods are evaluated, such as continuous laser, flash lamp and induction. The study also includes conditions for miniaturization andautomation of the inspection methods. For welds difficult to access, thermography is a suggested as a possible inspection method.

Keywords
Thermography, surface cracks, miniaturization, automation, weld inspection, limited access
National Category
Manufacturing, Surface and Joining Technology
Research subject
ENGINEERING, Manufacturing and materials engineering; Production Technology
Identifiers
urn:nbn:se:hv:diva-7084 (URN)
Conference
6th International Symposium on NDT in Aerospace, 12-14th November 2014, Madrid, Spain
Available from: 2014-12-09 Created: 2014-12-05 Last updated: 2018-08-12Bibliographically approved
Garcia de la Yedra, A., Fernandez, E., Beizama, A. M., Fuente, R., Echeverria, A., Broberg, P., . . . Henrikson, P. (2014). Defect strategies in Nickel Superalloys weld using active thermography. In: 12th International Conference on Quantitative InfraRed Thermography, 7-11/7 Bordeaux: . Paper presented at 12th International Conference on Quantitative InfraRed Thermography (pp. 1-9).
Open this publication in new window or tab >>Defect strategies in Nickel Superalloys weld using active thermography
Show others...
2014 (English)In: 12th International Conference on Quantitative InfraRed Thermography, 7-11/7 Bordeaux, 2014, p. 1-9Conference paper, Published paper (Refereed)
Abstract [en]

As a result of extreme operation conditions in gas turbines, high resistance materials with excellent behaviour at high temperature are required. Alloys, such as MarM-247 nickel based superalloy, with excellent mechanical properties at very high temperature (even at 85 % of their melting point) are being used in these applications. This extraordinary behaviour is mainly due to the presence of a strengthening phase (γ’) with the following chemical composition: Ni3(Al, Ti). However, during welding these materials are susceptible to cracking and this is why weld inspections become crucial. In this work different strategies for defect detection in welds are introduced, all of them based on active thermography. The work covers aspects such as different excitation and data evaluation strategies.

Keywords
Defect detection, Thermography, Excitation source
National Category
Production Engineering, Human Work Science and Ergonomics
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-6541 (URN)
Conference
12th International Conference on Quantitative InfraRed Thermography
Projects
WeldMindt
Available from: 2014-08-25 Created: 2014-08-25 Last updated: 2018-08-10Bibliographically approved
Broberg, P. (2014). Imaging and analysis methods for automated weld inspection. (Doctoral dissertation). Luleå: Luleå University of Technology
Open this publication in new window or tab >>Imaging and analysis methods for automated weld inspection
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

All welding processes can give rise to defects, which weakens the joint and can eventually lead to the failure of the welded structure. In order to inspect welds for detects, without affecting the usability of the product, non-destructive testing (NDT) is needed. NDT includes a wide range of different techniques, based on different physical principles, each with its advantages and disadvantages. The testing is often performed manually by a skilled operator and in many cases only as spot-checks. Today the trend in industry is to move towards thinner material, in order to save weight for cost and for environmental reasons. The need for inspection of a larger portion of welds therefore increases and there is an increasing demand for fully automated inspection, including both the mechanised testing and the automatic analysis of the result. Compared to manual inspection, an automated solution has advantages when it comes to speed, cost and reliability. A comparison of several NDT methods was therefore first performed in order to determine which methods have most potential for automated weld inspection. Automated analysis of NDT data poses several difficulties compared to manual data evaluation. It is often possible for an operator to detect defects even in noisy data, through experience and knowledge about the part being tested. Automatic analysis algorithms on the other hand suffer greatly from both random noise as well as indications that originate from geometrical variations. The solution to this problem is not always obvious. Some NDT techniques might not be suitable for automated inspection and will have to be replaced by other, better adapted methods. One such method that has been developed during this work is thermography for the detection of surface cracks. This technique offers several advantages, in terms of automation, compared to existing methods. Some techniques on the other hand cannot be easily replaced. Here the focus is instead to prepare the data for automated analysis, using various pre-processing algorithms, in order to reduce noise and remove indications from sources other than defects. One such method is ultrasonic testing, which has a good ability for detecting internal defects but suffers from noisy signals with low spatial resolution. Work was here done in order to separate indications from corners from other indications. This can also help to improve positioning of the data and thereby classification of defects. The problem of low resolution was handled by using a deconvolution algorithm in order to reduce the effect of the spread of the beam.The next step in an automated analysis system is to go beyond just detection and start characterising defects. Using knowledge of the physical principles behind the NDT method in question and how the properties of a defect affect the measurement, it is sometimes possible to develop methods for determining properties such as the size and shape of a defect. This kind of characterisation of a defect is often difficult to do in the raw data, and is therefore an area where automated analysis can go beyond what is possible for an operator during manual inspection. This was shown for flash thermography, where an analysis method was developed that could determine the size, shape and depth of a defect. Similarly for laser ultrasound, a method was developed for determining the size of a defect.

Place, publisher, year, edition, pages
Luleå: Luleå University of Technology, 2014. p. viii, 68 s.
Series
Doctoral thesis / Luleå University of Technology, ISSN 1402-1544
Keywords
Welding, materials
National Category
Materials Engineering
Research subject
ENGINEERING, Manufacturing and materials engineering
Identifiers
urn:nbn:se:hv:diva-6696 (URN)978-91-7439-931-8 (ISBN)978-91-7439-932-5 (ISBN)
Opponent
Available from: 2014-09-17 Created: 2014-09-17 Last updated: 2016-02-08Bibliographically approved
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-7748-0565

Search in DiVA

Show all publications