Bernd Valeske

Fraunhofer Institute for Nondestructive Testing IZFP | IZFP · Business Unit Industrial Processing and Assembly

Pulsed thermography is an indispensable tool in the field of non-destructive evaluation. However, the data generated by this technique can be challenging to analyze and require expertise to interpret. With the rapid progress in deep learning, image segmentation has become a well-established area of research. This has motivated efforts to apply deep...

Pulsed thermography is a vital technique in the nondestructive evaluation field. However, its data analysis can be complex and requires skilled experts. Advances in deep learning have yielded exceptional results, including image segmentation. Therefore, many efforts have been made to apply deep learning methods to data processing for nondestructive...

Analyzing eigenfrequencies by acoustic resonance testing enables a fast screening of components regarding structural defects. The eigenfrequencies of each specific part depend on the general geometric and material properties, including tolerable part-to-part variations, as well as on possible structural flaws. Separating good parts from defective o...

Cognitive sensor systems (CSS) determine the future of inspection and monitoring systems for the nondestructive evaluation (NDE) of material states and their properties and key enabler of NDE 4.0 activities. CSS generate a complete NDE 4.0 data and information ecosystem, i. e. they are part of the materials data space and they are integrated in the...

Convolutional neural networks were used for multiclass segmentation in thermal infrared face analysis. The principle is based on existing image-to-image translation approaches, where each pixel in an image is assigned to a class label. We show that established networks architectures can be trained for the task of multiclass face analysis in thermal...

Industry 4.0 (I4.0) describes the current revolution of the industrial world with a strong impact on the complete production sector. Data about production processes and the corresponding material and product status are the key elements. All over the world, the protagonists of I4.0 are facing the challenges to define appropriate concepts for I4.0 in...

A neural network (NN) for semantic segmentation (U-Net) was used for the detection of crack-type defects from thermography sequences. For this task, data sequences of forged steel parts were acquired through induction thermography and the corresponding phase images calculated. The results for defect detection were quantitatively evaluated using Int...

Die Zustandserfassung digitaler Produktinformationen ist essentiell für die Einbettung einer fortschrittlichen und produktionsbegleitenden Qualitätssicherung. Ein Beispiel hierfür ist die berührungslose Erfassung von Oberflächenrissen an Bahnrädern von Hochgeschwindigkeitszügen, mit Hilfe der bildgebenden, vollautomatisierbaren Induktions-Thermogra...

Die Rekonstruktion der Lage und Größe von inneren Fehlern und Strukturen in Werkstoffen aus zeitaufgelösten Thermografiedaten der Oberfläche ist eine Aufgabe, die im Vergleich zu anderen zerstörungsfreien Prüfverfahren bisher nur ansatzweise gelungen ist. Im höherdimensionalen Fall beschränken sich Rekonstruktionsversuche meist auf die gleichzeitig...

For decades, dating of Roman Terra Sigillata pottery was assessed by visual inspection. Since the ornaments and indentations on the ceramic surface are characteristic for the manufacturing workshop in the Roman Empire, archeologists have used chronological catalogues to assign the sherds to its time period. This paper should underpin the applicatio...

Grundlagen-Anwendung-Normung Dr. rer. nat. U. Netzelmann, Dipl.-Ing. A. Ehlen und Prof. Dr.-Ing. B. Valeske, Fraunhofer-Institut für Zerstörungsfreie Prüfverfahren, Saarbrücken Kurzfassung Die induktive angeregte Thermografie wird als zerstörungsfreies Prüfverfahren zum Nachweis von Oberflächenfehlern in Metallen vorgestellt. Es folgt eine Beschrei...

Recently, basalt-carbon hybrid composite structures have attracted increasing attention due to their better damage tolerance, if compared with carbon fiber-reinforced polymer composites (CFRP). Low-velocity is considered as one of the most severe threats to composite materials as it is usually invisible and it occurs frequently in service. With thi...

Das Fraunhofer IZFP beschäftigt sich seit Jahren mit der automatisierten induktiv angeregten Thermografie als alternative Prüfmethode zur Magnetpulver- und Farbeindringmethode. Aufgabenstellungen aus der Herstellung und aus dem Betrieb von Eisenbahnrädern, Wellen und Schienen aus der Verkehrstechnik führten zu einer verstärkten Hinwendung der Forsc...

Induction thermography is an active thermal testing technique based on generation of eddy currents in an electrically conducting material. The technique found successful applications for surface crack detection in various industrial branches, with the general aim of searching for alternatives to magnetic particle or liquid penetrant testing. Due to...

A survey on theory, characteristic quantities and the experimental technique of induction thermography is given. Induction thermography is used for surface defect detection in forged parts of ferromagnetic steel at typical frequencies of 100–300 kHz. The sensitivity for crack detection is comparable to magnetic particle inspection. A hidden defect...

Adhesive bonding has a great potential for future lightweight high-loaded structures in the aeronautic industry. A prerequisite for such an application is that the bond quality of the adhesive joint can be assessed in a non-destructive way. However, the use of classical Non-Destructive Techniques (NDT) does not allow the evaluation of the adhesion...

This chapter aims to establish the state-of-the-art with regard to non-destructive testing (NDT) techniques of adhesively bonded composite materials, with a special focus on the aerospace industry, and composite substrates. Typical material defects, as well as quality management through NDT methods throughout the product life cycle, are introduced....

Adhesive bonding for lightweight application, especially with carbon fiber reinforced polymers (CFRP) materials regarding aerospace application has a large development potential. Requirements involve a strict control of the bonding process to ensure the quality of the assembly. Several factors may however influence the adherent surface prior to bon...

Induction thermography has been extended to the low frequency range of 300 to 2600 Hz. The electromagnetic skin depth is thereby increased in a way that in ferromagnetic steel hidden defects with 1.25 mm coverage could be detected by interaction of the induction currents with the crack. Numerical simulations of the internal current and temperature...

Die induktiv angeregte Thermografie bietet sich für die automatisierte zerstörungsfreie Prüfung auf oberflächennahe Fehler in Metallen, insbesondere Stählen, an. Diese Prüftechnik arbeitet vollständig berührungslos und sehr schnell. Daher eignet sie sich für kontinuierlich messende Online Prüfsysteme in der Produktionslinie und zur automatisierten,...

Kurzfassung Die induktiv angeregte Thermografie stellt eine Alternative zu klassischen Oberflächenrissprüftechniken wie der Magnetpulverprüfung oder auch der Farbeindringprüfung bei leitfähigen Materialien, insbesondere ferromagnetischen und austenitischen Stählen dar. Im vorliegenden Beitrag sollen die Grundlagen des Verfahrens, einige Anwendungsb...

The induction thermography has become an alternative technique to the classical methods of surface crack testing as the magnetic particle testing or the penetration testing for conductive materials, especially for ferromagnetic or austenetic steels. In this contribution the basics of the technique, some applications, the detection limits and specia...

Ein Algorithmus zur 3D-Visualisierung von Thermographiebildern und Thermographiebildsequenzen aus der Prüfung mit aktiver Thermographie wurde erstellt. Der Benutzer stellt zunächst durch Eingabe von Referenzpunkten eine Verbindung zwischen dem Geometriemodell des Prüfobjekts und den aus ausreichend vielen Ansichten gemessenen Thermographiedaten her...

Mechanical pretreatment is the oldest and most common technique for improving the performance of adhesive metal bonds. But it is poorly understood, how mechanical pretreatment affects the surface state of the metal adherend and how in turn the pretreated surface influences the properties of the applied adhesive or the whole joint, respectively. Thi...

The aluminium–magnesium alloy EN-AW 5754 is studied with SEM, energy-dispersive x-ray imaging (EDX), AES and XPS after treatment by chemical etching and blasting with glass beads or alumina grit. Blasting proves to change more than the surface profile. The freshly treated surfaces are fully covered with a carbon contamination of characteristic oxyg...

The excellent biocompatibility of titanium and its alloys used, for example, for medical devices, is associated with the properties of their surface oxide. For a better understanding of the tissue reaction in contact with the oxide layer, knowledge of the chemical and physical properties of this layer is of increasing interest. In this study, titan...

Two major effects are observed during annealing. First, some cyanate groups hydrolyze into carbamate structures on Al and Au. The reaction is driven by the metal surface and both hydroxyl groups and adsorbed water can be involved. On Al, where the carbamate production is most prominent, a part of the cyanate groups in the prepolymer is expected to...

For the first time, polycyanurate thin films are prepared by thermal deposition from the vapor of the bisphenol A dicyanate. The deposited films are characterized by AFM, infrared reflection spectroscopy and TOF-MS with respect to their morphology, chemical structure and thermal stability. In contrast to conventional film preparation techniques, th...

Surface modification of components by laser-beam-hardening is of increasing interest because of the possibility of local treatments and its easy integration into the production process. Because of various parameters influencing the hardening process, nondestructive testing techniques are desired for monitoring of machining quality. Up to now, only...

Although the aerospace industry already has experience with adhesive bonding on carbon fibre reinforced polymers (CFRP) technology, a great potential for the manufacturing of high-loaded structures exists. A prerequisite for such an application is that the quality of the adhesive bond can be controlled. Various non-destructive testing (NDT) techniq...

Due to the increased use of carbon fibre reinforced plastics (CFRP) and the constant urge for lighter structures, adhesive bonding as an assembly technology has a great potential for high-loaded structures in the aeronautic industry. A prerequisite for such an application is that the bond quality of the adhesive joint can be controlled in a non des...

In der hier vorgestellten Arbeit wurden als einfaches Modell für die Klangprüfung Rundstäbe aus Aluminium mit verschiedenen Durchmessern und Längen untersucht. Vorteil der einfachen Modellproben ist, dass analytische Modelle angewendet werden können, mit deren Hilfe der Einfluss von Formabweichungen und Änderungen in den elastischen Konstanten auf...