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  • 1. Batungwanayo, Guillaume
    et al.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Electrical and Automation Engineering.
    Weld Joint Tracking System in an Automatic Inspection Cell by Using Emissivity Variation2014In: Proceedings of the 6th International Swedish Production Symposium 2014 / [ed] Stahre, Johan, Johansson, Björn & Björkman, Mats, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    Thermography has proven to be a suitable nondestructive testing method for automatic crack inspection of welds. However automatic weld inspection raises challenges. E.g. the position of the weld might not be exactly as the predefined weld seam, and a weld joint tracking system is needed. To reduce the number of equipment used, a solution is presented in this papers. The infrared camera in the thermography system is a carrier of information of the weld path. This is used for the weld joint tracking system. It is shown that the weld joint tracker is fast enough for an on-line automatic inspection.

  • 2.
    Bergström, Per
    et al.
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Luleå, Sweden.
    Fergusson, Michael
    Xtura AB, Kungsbacka, Sweden.
    Folkesson, Patrik
    Xtura AB, Kungsbacka, Sweden.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production System.
    Ottosson, Mattias
    University West, Department of Engineering Science, Division of Production System.
    Andersson, Alf
    Chalmers University of Technology, Department of Product and Production Development, Gothenburg, Sweden.
    Sjödahl, Mikael
    Luleå University of Technology, Department of Engineering Sciences and Mathematics, Luleå, Sweden.
    Automatic in-line inspection of shape based on photogrammetry2016In: The 7th International Swedish Production Symposium, SPS16, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Academy , 2016, p. 1-9Conference paper (Refereed)
    Abstract [en]

    We are describing a fully automatic in-line shape inspection system for controlling the shape of moving objects on a conveyor belt. The shapes of the objects are measured using a full-field optical shape measurement method based on photogrammetry. The photogrammetry system consists of four cameras, a flash, and a triggering device. When an object to be measured arrives at a given position relative to the system, the flash and cameras are synchronously triggered to capture images of the moving object.From the captured images a point-cloud representing the measured shape is created. The point-cloud is then aligned to a CAD-model, which defines the nominal shape of the measured object, using a best-fit method and a feature-based alignment method. Deviations between the point-cloud and the CAD-model are computed giving the output of the inspection process. The computational time to create a point-cloud from the captured images is about 30 seconds and the computational time for the comparison with the CAD-model is about ten milliseconds. We report on recent progress with the shape inspection system.

  • 3.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Production Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production Systems.
    Analysis algorithm for surface crack detection by thermography with UV light excitation2016In: Quantitative InfraRed Thermography 2016: Abstracts / [ed] Kaczmarek, M. & Bujnowski, A., Gdańsk, Poland: Publishing Gdańsk University of Technology , 2016, p. 144-149Conference 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.

  • 4.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Process and Product Development.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Process and Product Development.
    Detection of Surface Cracks in Welds using Active Thermography2012In: Proceedings18th World Conference on Non-Destructive Testing: 16 - 20 April 2012, Durban, South Africa, South African Institute for Non-Destructive Testing (SAINT) , 2012, p. 1-5Conference paper (Refereed)
    Abstract [en]

    Surface cracks in welds can be detected using several non-destructive testing methods; among the more popular ones are eddy current, penetrant and magnetic particle testing. For an automatic inspection cell, the traditional techniques have limitations. Here we have investigated the possibility of using active thermography for detecting surface cracks in welds. This technique features advantages such as non-contact and high speed. The weld is illuminated using an infrared light source. Due to higher energy absorption in a surface crack, the defect will be identified as a hot spot when imaged by an infrared camera. Artificial weld defects (notches) are investigated by use of active thermography. Results from an inspection of real longitudinal cold cracks in a weld are also presented. The results show that active thermography looks promising for detection of even small cracks and notches, as long as they are open to the surface.

  • 5.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Sjödahl, Mikael
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Improved Corner Detection by Ultrasonic Testing using Phase Analysis2013In: Ultrasonics, ISSN 0041-624X, E-ISSN 1874-9968, Vol. 53, no 2, p. 630-634Article in journal (Refereed)
    Abstract [en]

    In ultrasonic testing, corners are used for sensitivity calibration in the form of notches, for measuring the sound velocity in the material, and as known reference points during testing. A 90° corner will always reflect incoming waves in the opposite direction due to a double reflection and therefore give a strong echo. This article presents a method for separating the echo from a corner from other echoes and more accurately find the position of the corner. The method is based on analysing the phase of the reflected signal. The proposed method was tested on a steel calibration block and the width of the indication was reduced by up to 50% compared to the amplitude signal. This results in a more accurate positioning of the corner. Using the phase instead of the amplitude will also improve the reliability, since reflections other than from corners will disappear.

  • 6.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Process and Product Development.
    Sjödahl, Mikael
    University West, Department of Engineering Science.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Process and Product Development.
    Comparison of NDT-methods for automatic inspection of weld defects2015In: International journal of materials & product technology, ISSN 0268-1900, E-ISSN 1741-5209, Vol. 50, no 1, p. 1-21Article in journal (Refereed)
    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.

  • 7.
    Broberg, Patrik
    et al.
    University West, Department of Engineering Science, Division of Process and Product Development.
    Sjödahl, Mikael
    University West, Department of Engineering Science, Division of Process and Product Development.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Process and Product Development.
    Improved Image Quality in Phased Array Ultrasound by Deconvolution2012In: Proceedings18th World Conference on Non-Destructive Testing: 16 - 20 April 2012, Durban, South Africa, South African Institute for Non-Destructive Testing (SAINT) , 2012, p. 1-5Conference paper (Refereed)
    Abstract [en]

    High contrast and resolution in phased array ultrasonic images are of importance for accurate evaluation. The spread of the ultrasonic beam is one cause of the images being unsharp. One technique for reducing the influence of the beam spread, and thereby improving the image quality, is by deconvolving the data with the point spread function of the ultrasonic beam. By assuming that the material is homogeneous, the point spread function of the beam can be simulated using diffraction theory. Results from a deconvolution performed on data acquired from a side drilled hole in a steel calibration block are presented. It is shown that a significant improvement in sharpness and contrast can be achieved.

  • 8.
    Fuente, Raquel
    et al.
    IK4-LORTEK, Ordizia, Spain.
    García de la Yedra, Aitor
    IK4-LORTEK, Ordizia, Spain.
    Beizama, Ane Miren
    IK4-LORTEK, Ordizia, Spain.
    Fernández, Erik
    IK4-LORTEK, Ordizia, Spain.
    Gorostegui Colinas, Eider
    IK4-LORTEK, Ordizia, Spain.
    Echeverria, Alberto
    IK4-LORTEK, Ordizia, Spain.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Thorpe, Nigel
    Tecnitest ingenieros, Madrid, Spain.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Henrikson, Per
    GKN Aerospace Engine Systems Sweden, Trollhättan, Sweden.
    Development and demonstration of an automated system for limited access weld inspection by using infrared active thermography2015In: Proceedings 7th International Symposium on NDT in Aerospace, Berlin, 2015, p. 1-8Conference 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.

  • 9.
    Garcia de la Yedra, Aitor
    et al.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Fernandez, Erik
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Beizama, Ane Miren
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Fuente, R.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Echeverria, A.
    Control and Evaluation, IK4-LORTEK; Arranomendia Kalea 4A, Ordizia, Spain.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Henrikson, Per
    GKN Aerospace Engine Systems.
    Defect strategies in Nickel Superalloys weld using active thermography2014In: 12th International Conference on Quantitative InfraRed Thermography, 7-11/7 Bordeaux, 2014, p. 1-9Conference 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.

  • 10.
    Hatefipour, Saeid
    et al.
    University West, Department of Engineering Science, Division of Automation Systems. saeid@termisk.se.
    Ahlberg, Jörgen
    Linköping University.
    Wren, Joakim
    University West, Department of Engineering Science, Division of Automation Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Thermal non-destructive testing: modeling, simulation and experiments for improved localization of hidden defects2014In: The 12th International Conference on Quantitative Infrared Thermography, 2014, p. 1-8Conference paper (Refereed)
    Abstract [en]

    During the last decades, a substantial amount of research and practical work has been conducted on non-destructive testing of materials using thermography. The performed studies elucidate the potential of various types of thermal non-destructive testing (TNDT) for different materials and applications, including various types of defects. This paper presents a method for detecting in-depth defects in metallic materials and a simulation model for the heat transfer in the material. Experiments are performed on a test specimen with artificial defects (flat-bottom holes). The detection method exploits spatiotemporal analysis in order to find deviations from a model of normality, and shows novel results. Thermal modelling is performed in order to have a base-line simulation model enable us to (a) investigate affecting parameters without repeating the experiments and (b) generalize the results and extend their validity to other cases. Results show that there is an acceptable compliance between simulated and measured thermal data. 

  • 11.
    Nilsson, Patric
    et al.
    Volvo Aero.
    Appelgren, Anders
    University West, School of Business, Economics and IT, Division of Computer Science and Informatics.
    Henrikson, Per
    Volvo Aero.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Process and Product Development.
    Automatic Ultrasonic testing for Metal Deposition2012In: Proceedings 18th World Conference on Non-Destructive Testing: 16 - 20 April 2012, Durban, South Africa, Durban, 2012, p. 1-10Conference paper (Refereed)
    Abstract [en]

    Metal Deposition (MD) is a method to build three dimensional metal geometries by welding using filler wire or powdered metal. NDT of a MD feature is required when the feature is located in an area of high stress or could be a potential hazard to the part. Ultrasonic testing (UT) can be used to detect pores, linear indications and lack of fusion in welds. This method has limitations when it comes to large parts with complex geometries with various shapes and sizes. A flexible method for inspecting complex geometries is to mount an ultrasonic water flow probe (squirter) on a robot. The robot can then follow a pre-programmed path to achieve full inspection of the feature. This paper shows results and functionality from a system where a squirter probe was used together with a standard industrial robot. Results from a scanning of a three-dimensional MD-structure are also presented.

  • 12.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Process and Product Development.
    Vibration Induced Disturbances in Automatic Non-destructive Testing2012In: Proceedings 18th World Conference on Non-Destructive Testing 16 - 20 April 2012, Durban, South Africa, Durban, 2012, p. 1-6Conference paper (Refereed)
    Abstract [en]

    The interest in automatic inspection of welds has increased during the last decade. An automatic inspection cell is self-acting both by scanning the inspected test piece and by evaluation of the resulting images. For automatic evaluation, high quality of the resulting images is essential. The non-smooth movement of the NDT-sensor when mounted on a robot-arm will have influence on the results. This paper focus on evaluation of the vibration induced disturbances due to the mounting of the sensor and the movement of the robot in an automatic cell. A thermography system detecting the geometry of welds is used in this study and both stationary and continuous movement of the IR camera are studied. The vibration due to the mounting on a robot arm are quantified and compared.

  • 13.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Ahlberg, Jörgen
    Linköping University.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation Systems.
    Sjökvist, Stefan
    Termisk systemteknik AB.
    Automatic Inspection of Spot Welds by Thermography2014In: Journal of nondestructive evaluation, ISSN 0195-9298, E-ISSN 1573-4862, Vol. 33, no 3, p. 398-406Article in journal (Refereed)
    Abstract [en]

    The interest for thermography as a method for spot weld inspection has increased during the last years since it is a full-field method suitable for automatic inspection. Thermography systems can be developed in different ways, with different physical setups, excitation sources, and image analysis algorithms. In this paper we suggest a single-sided setup of a thermography system using a flash lamp as excitation source. The analysis algorithm aims to find the spatial region in the acquired images corresponding to the successfully welded area, i.e., the nugget size. Experiments show that the system is able to detect spot welds, measure the nugget diameter, and based on the information also separate a spot weld from a stick weld. The system is capable to inspect more than four spot welds per minute, and has potential for an automatic non-destructive system for spot weld inspection. The development opportunities are significant, since the algorithm used in the initial analysis is rather simplified. Moreover, further evaluation of alternative excitation sources can potentially improve the performance.

  • 14.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Evaluation of non-destructive testing methods for automatic quality checking of spot welds2012Report (Other academic)
    Abstract [en]

    Car bodies are today more often made of high strength steel. In high strength steel spot welds are more friable and it is necessary to have higher demands on the inspections of spot welds. Quality control of spot weld can be either destructive or non-destructive. Destructive testing is still the most common method to test spot weld. The non-destructive methods that are investigete in this project are visual inspektion (VT), penetrant testing (PT), eddy current testing (ET), ultrasonic testing (UT), magnetic paticle testing (MT) and X-ray testing (RT). Other NDT methods are acoustic emission (AE), digital sheargraphy and IR-termography (IRT). These methods are investigated with focus on the possibility to detect Lens Diameter, stick welds, expulsions, porosity and cracks. And the possibility to automation of the method with focus on size and weight of the system, protection equipment, contact or contactless, one or two sided, position accuracy, and result in real-time.

    Only tree NDT methods, UT, RT and IRT, can detect all discontinuities that we looking for in RSW. The thermography system has the largest potential to be a NDT system for spot weld in the future, mainly because the method is non-contact, which helps when you have the opportunity to searching on a surface instead of a specific position. The main problem with this method is that there is no software for analysing the results to obtain lens diameter.

  • 15.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Ahlberg, Jörgen
    Termisk Systemteknik AB.
    Lundevall, Åsa
    SWEREA IVF.
    Albinsson, Ola
    SWEREA IVF.
    Automated NDT cell for quality checking of spot welds2013Report (Other academic)
    Abstract [en]

    This report is written within Spotlight WP5 financed by the FFI programme within Vinnova.

    Thermography is a non-destructive testing method based on measurement of the heat distribution by an infrared camera. The method is suitable for automatic inspection since it is a full filed and non-contact method.

    A thermography system with an analysis tool developed by Termisk Systemteknik AB is investigated as an inspection method for spot weld. The system is able to detect spot welds, measure the diameter and separate a spot weld from a stick weld. The algorithms used in the analysis are rather simplified and the development opportunities are significant.

    A fully automated NDT-cell for spot weld inspection is presented. The automation includes a six axis industrial robot and communication for handling the information flow. This comprised the identification of the inspected spot weld and the reporting to the overall system as to the operator.

    A failure modes and effects analysis (FMEA) of the automated NDT-cell is accomplished and the most important actions are reported

    A business case for implementing a automated NDT-cell was included in the project. In this business case the most promising quality check concepts for NDT spot weld will be presented and compared with the other identified methods.

  • 16.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Surface crack detection using infrared thermography and ultraviolet excitation2014In: 12th International Conference on Quantitative InfraRed Thermography, 2014, p. 1-7Conference paper (Refereed)
    Abstract [en]

    High signal to noise ratio is important within non-destructive testing. To achieve automatic inspection, including automatic evaluation, it is even more important. Infrared thermography is a suitable method for automatic inspection. One drawback with thermography of metallic structures is that due to shiny surfaces the reflectance is high and the signal to noise ratio will be low. This paper presents results from surface crack detection with thermography using ultraviolet excitation. The tested component is a welded Inconel plate with a highly reflective surface. Ultraviolet excitation is shown to be a suitable excitation method and high signal to noise is achieved.

  • 17.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Mechanical Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering. University West, Department of Engineering Science, Division of Production System.
    Possibilities and Limitations of Automated Non-Destructive Testing of Welds2012In: Proceedings of the 5th International Swedish Production Symposium: 6th-8th of November 2012 Linköping, Sweden / [ed] Mats Björkman, Linköping, 2012, p. 3-9Conference paper (Refereed)
  • 18.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Fernandez, Erik
    IK4-LORTEK, Ordizia, Spain.
    Garcia de la Yedra, Aitor
    IK4-LORTEK, Ordizia, Spain.
    Henrikson, Per
    GKN Aerospace Engine Systems, Trollhättan, Sweden.
    Thorpe, Nigel
    Tecnitest Ingenieros S.L, Madrid, Spain.
    Automatic thermography inspection of welded components with limited access2014In: Proceedings of 6th International Symposium on NDT in Aerospace, 12-14th November 2014, Madrid, Spain, 2014, p. 1-10Conference 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.

  • 19.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Production System.
    Garcia de la Yedra, Aitor
    IK4-LORTEK, Ordizia, Spain.
    Fuente, Raquel
    IK4-LORTEK, Ordizia, Spain.
    Beizama, Ane Miren
    IK4-LORTEK, Ordizia, Spain.
    Fernandez, Erik
    IK4-LORTEK, Ordizia, Spain.
    Thorpe, Nigel
    Tecnitest ingenieros, Madrid, Spain.
    Henriksson, Per
    GKN Aerospace Engine Systems Sweden, Trollhättan, Sweden.
    Automated inspection of welds with limited access by use of active thermography with laser line excitation2016Conference 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.

  • 20.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Automation Systems.
    Henrikson, Per
    GKN Aerospace Engine System, Trollhättan.
    Ultraviolet excitation for thermography inspection of surface cracks in welded joints2014In: Nondestructive Testing and Evaluation, ISSN 1058-9759, E-ISSN 1477-2671, Vol. 29, no 4, p. 332-344Article in journal (Refereed)
    Abstract [en]

    Infrared thermography is a non-contact and full field inspection method which has proven to be suitable for automatic surface crack detection. For automatic analysis of the inspection results, a high signal-to-noise ratio (SNR) is required. In this paper an alternative excitation method, using ultraviolet (UV) illumination, is presented and evaluated. Artificial surface defects, so-called notches, in a titanium plate are detected both in the weld seam and in the heat affected zone. Notches with a size from 80 mm in width and 250 mm in length are detected. The SNR using UV illumination is compared with that using flash lamp excitation. The results show that UV illumination using a mercury lamp is a good alternative as excitation source for thermography when detecting surface cracks. To validate the excitation method, results from real surface cracks are included.

  • 21.
    Runnemalm, Anna
    et al.
    University West, Department of Engineering Science, Division of Automation Systems.
    Liu, Tongwein
    Ericsson, Mikael
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Appelgren, Anders
    University West, Department of Engineering Science, Division of Automation and Computer Engineering.
    Influence of Vibration Induced Disturbances in an Automatic Inspection Cell2013In: Robotics in Smart Manufacturing / [ed] Pedro Neto,António Paulo Moreira, 2013, p. 191-202Conference paper (Refereed)
    Abstract [en]

    In the modern manufacturing industry, quality assurance is important. Over the last few years, the interest in automatic inspection has increased and automatic non-destructive testing (NDT) has been introduced. A general automated inspection cell consists of a mechanized system for scanning and a computer system for automatic analysis of the data. In the manufacturing industry, it is preferable to use industrial robots as the scanning equipment since they offer great flexibility, excellent support organization and the in-house know-how is normally high. Another benefit is that a robot can carry different inspection equipment and an inspection cell can therefore include more than one NDT method. For an automatic analysis, high quality of the resulting data is essential. However, a non-stable condition of the NDT sensor mounted on the robotic arm may influence the results. This paper focuses on the influence of the vibration induced disturbances on the results from an NDT system. Vibration amplitude of a point to point robot movement on the robotic arm is measured. The influence of vibration disturbances on the inspection results are evaluated on the thermal images from a thermography system mounted on a six axis industrial robot. The thermal images taken by the system during the movement and after the stop of the robot are evaluated, and the influence of the vibration in these two situations is considered.

  • 22.
    Sikström, Fredrik
    et al.
    University West, Department of Engineering Science, Division of Production System.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production System.
    Broberg, Patrik
    University West, Department of Engineering Science, Division of Production System.
    Nilsen, Morgan
    University West, Department of Engineering Science, Division of Production System.
    Svenman, Edvard
    University West, Department of Engineering Science, Research Enviroment Production Technology West.
    Evaluation of non-contact methods for joint tracking in a laser beam welding application2016In: The 7th International Swedish Production Symposium, Conference Proceedings: 25th – 27th of October 2016, Lund: Swedish Production Symposium , 2016, p. 1-6Conference 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.

  • 23.
    Svenman, Edvard
    et al.
    University West, Department of Engineering Science, Division of Automation Systems. GKN Aerospace Sweden AB.
    Rosell, Anders
    GKN Aerospace, Sweden; Chalmers University of technology, Sweden.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Automation Systems.
    Christiansson, Anna-Karin
    University West, Department of Engineering Science, Division of Automation Systems.
    Henrikson, Per
    GKN Aerospace, Sweden.
    Weld gap position detection based on eddy current methods with mismatch compensation2015In: Proceedings of JOM 18 International conference on joining materials, Helsingör, Danmark, april 26-29, 2015, JOM-institute , 2015, p. 1-9Conference paper (Refereed)
    Abstract [en]

    The paper proposes a method for finding the accurate position of narrow gaps, intended for seam tracking applications. Laser beam welding of butt joints, with narrow gap and weld width, demand very accurate positioning to avoid serious and difficult to detect lack of fusion defects. Existing optical and mechanical gap trackers have problems with narrow gaps and surface finish. Eddy current probes can detect narrow gaps, but the accuracy is affected by mismatch in height above the surface on either side of the gap. In this paper a non-contact eddy-current method, suitable for robotic seam tracking, is proposed. The method is based on the resistive and inductive response of two absolute eddy current coils on either side of the gap to calculate a position compensated for height variations. Additionally, the method may be used to estimate the values of height and gap width, which is useful for weld parameter optimization. To investigate the response to variations in height, the method is tested on non-magnetic metals by scanning one commercially available eddy current probe across an adjustable gap and calculating the expected response for a two-probe configuration. Results for gap position are promising, while mismatch and gap width results need further investigation.

  • 24.
    Svenman, Edvard
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. GKN Aerospace.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production Systems.
    A complex response inductive method for improved gap measurement in laser welding2017In: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 88, no 1-4, p. 175-184Article in journal (Refereed)
    Abstract [en]

    Laser welding needs precise measurement of weldgap position to avoid weld defects. Most often, optical measurement methods are used, but well-aligned narrow gaps canbe difficult to detect. An improved inductive method capable of detecting zero gaps in square butt joints is proposed. The new method uses two eddy current coils, one on each side of the gap, and measures the complex response of the individual coils, i.e. both the inductive and resistive response. By combining the coil responses, both the position and the geometry of the weld gap can be estimated. The method was experimentally investigated by traversing a single coil over an adjustable gap between two plates and combining the measured coil responses into a simulated two-coil probe. The gap was adjusted in both misalignment and gap width up to 0.4 mm. Comparing the results to known settings and positions shows that gap position is measured to within 0.1 mm, if the probe is within a working area of 1 mm from the gap in both position and height. Results from the new method were compared to simulations, from the same experimental data, of a previously reported method where the coils were electrically combined by wiring them together. The previous method can give accurate results but has a much smaller working area and depends on servo actuation to position the probe above the gap. The improved method gives better tolerance to varying misalignment and gap width, which is an advantage over previous inductive methods.

  • 25.
    Svenman, Edvard
    et al.
    University West, Department of Engineering Science, Research Enviroment Production Technology West. GKN Aerospace Engine Systems.
    Runnemalm, Anna
    University West, Department of Engineering Science, Division of Production Systems.
    Model based compensation of systematic errors in an inductive gap measurement method2017In: Measurement : Journal of the International Measurement Confederation, ISSN 0263-2241, Vol. 105, p. 17-24Article in journal (Refereed)
    Abstract [en]

    This paper presents an improvement to a recently presented inductive gap measurement method, using a model to reduce systematic errors. Gap measurement is important in laser keyhole welding, where the laser beam and the resulting weld seam are very narrow, requiring high precision in alignment and gap preparation. The previously reported method for gap measurement uses one inductive coil on each side of the gap, each measuring distance to the gap and lift off above a plate, to estimate the position, width and alignment of the gap in a square butt joint. The method can detect zero width gap and shows position error less than 0.1 mm, but gap width and alignment measurement suffer from systematic errors. The improvement is based on a model that is designed to describe these systematic errors as functions of the gap dimensions. The model relies on observations of experimental data, and is calibrated to a small set of measurements. Using the model with the initial estimate of the gap dimensions to compensate the coil measurements, an improved estimate of the gap dimensions can be calculated. The errors in the compensated results are within 0.1 mm except for gap width, which still suffers from the effect of combined gap width and misalignment.

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