Filtern
Erscheinungsjahr
Dokumenttyp
- Vortrag (34)
- Beitrag zu einem Tagungsband (19)
- Zeitschriftenartikel (18)
- Beitrag zu einem Sammelband (18)
- Posterpräsentation (5)
Schlagworte
- Zerstörungsfreie Prüfung (12)
- Radar (11)
- Radiografie (9)
- Strukturaufklärung (7)
- Videoskopie (7)
- Baudenkmäler (6)
- Image quality (5)
- Laminography (4)
- POD (4)
- Zuverlässigkeit (4)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (7)
- 8.5 Röntgenbildgebung (7)
- 7 Bauwerkssicherheit (4)
- 7.2 Ingenieurbau (4)
- 5 Werkstofftechnik (2)
- 5.3 Polymere Verbundwerkstoffe (2)
- 7.4 Baustofftechnologie (1)
- 8.0 Abteilungsleitung und andere (1)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (1)
- 8.4 Akustische und elektromagnetische Verfahren (1)
Eingeladener Vortrag
- nein (34)
High-energy radiography is traditionally used for the detection of defects in thick-walled, bulky components. It is also used for testing the integrity of components for civil and security-related applications, e.g. containers. The combination of high-energy sources with digital detector arrays or line cameras allows carrying out the tests either in a shorter time compared to film technique, or with higher contrast sensitivity.
The high-energy X-ray laboratory "HEXYLab" at BAM is a joint laboratory in which future users, manufacturers and scientists collaborate to initiate and develop joint development projects. The new universal manipulation system “HEXYTech” provides the engineering and technical base for meeting different requirements within HEXYLab.
Different types of trajectories for tube, object and detector can be programmed with a total of 13 rotational and linear axes. In particular, large objects with complex geometries can be examined. Measurements can be acquired as 2D images via standard radiography as well as 3D volumes from laminography or computed tomography reconstructions.
The general rules for the application of high-energy radiography with digital detectors (imaging plates, digital detector arrays) were determined within the framework of the European project "HEDRad" (High Energy Digital Radiography) and added to the standard DIN EN ISO 17636-2.
The paper gives an overview of the test technique and introduces several applications on the basis of experiments and reconstructed 3D- images.
A comparative study on the performance of digital detector systems for high energy applications
(2014)
For cast components reaching or exceeding total material thicknesses of 150mm, high energy sources such as linear accelerators or Betatrons are required in order to obtain reasonable exposure times. In this study, the performance of digital detector systems, involving imaging plates (IP) and digital detector arrays (DDA), was evaluated with respect to the testing class B requirements as formulated in the standard EN ISO 17636-2. As a reference, traditional radiographic film and a Cobalt-60 source was used. With film exposures, testing class B was achieved with Co-60 and Betatron (7.5 MV) at longer exposure times. The preliminary results show that the testing class B was not obtained with the examined digital detector arrays (DDA) and the high resolution imaging plates (IP) , even at 40, 60 and 80 minutes exposure time with a 7.5 MV Betatron. Class A was achieved using high resolution imaging plates with optimized metal filters between object and IPs and a high resolution DDA with intermediate Cu filters. Class A was also achieved applying a DDA with lower basic spatial resolution than required by Table B.13 of EN ISO 17636-2, but using the compensation principle as described in this standard. The next generation of digital detector arrays might potentially be able to obtain class B performance with the expected spatial resolution and sensitivity improvements.
Hot crack assessment during production and processing of metallic materials is an essential prerequisite for the safety of welded structures. The hot cracking investigations presented here were carried out as part of a study aimed at the development of Cr/Ni low transformation temperature filler materials. Low transformation temperature alloys open up the possibility for welding high strength steels. The externally loaded Modified Varestraint Transvarestraint hot cracking test was employed in the experiments described. The hot cracking resistance was evaluated with the help of light microscopy applied at the specimen surface. The proportionality between hot cracking susceptibility and Cr/Ni alloy content was explained by the altered solidification kinetics and by the enlarged solidification interval. The internal crack paths and the three-dimensional structure of the crack net in the material volume were examined using X-ray computer tomography. The total crack lengths for different material depths and circumjacent rectangular volumes, respectively, were be determined. An increasing hot cracking susceptibility with increasing Cr/Ni alloy content was also be established for the specimen volume.
Automatic segmentation of cracks using crack detection methods fails when applied on concrete with embedded reinforcements; it results in artifacts called false-detected cracks. We present a two-step approach to trace the cracks which reduces significantly detecting the false ones. In the first step, the reinforcements were found and removed from the 3D data set, and in the second step, the cracks were detected in the 3D data set free from reinforcements. To visualize and determine the structure and the degree of damages nondestructively, planar tomography as a special case of laminography was used.