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Methode und Prüfkörper zum Nachweis von Gussdefekten in Aluminiumbauteilen mit Computertomographie
(2009)
Computertomographische Aufnahmen von Objekten mit stark
voneinander abweichenden Absorptionseigenschaften stellen sowohl für den
Anwendungsbereich der zerstörungsfreien Prüfung als auch für den der
dimensionellen Messtechnik eine besondere Herausforderung dar. Die
Aufnahmekonfiguration kann bei Objekten dieser Art häufig nicht so gewählt
werden, dass die unterschiedlichen Materialeigenschaften mit ausreichender Qualität
abgebildet werden können. Aus diesem Grund ist eine objektive Bewertung der
Oberflächenmessung mit Hilfe eines in dieser Untersuchung eingeführten
Qualitätsmaßes erforderlich. Anhand der in dieser Arbeit vorgestellten
Prüfkörperserie soll der Einfluss der Materialzusammensetzung auf das
dimensionelle Messen mit CT erfasst und charakterisiert werden. Unter
Berücksichtigung der Qualitätsbewertung der Oberflächenpunkte erfolgt die
Berechnung der Form- und Abstandsabweichungen. Ziel ist es, die Genauigkeit der
Oberflächenmessung hinsichtlich unterschiedlicher Aufnahmeparameter und
Materialzusammensetzungen darzustellen. Anhand dieser Ergebnisse ist es möglich,
den computertomographischen Aufnahme- und Auswertungsprozess quantitativ zu
bewerten und Ursachen der Abweichungen zu diskutieren.
Phasenkontrastmessungen haben sich als hilfreich bei der
Kantenfindung von Strukturen mit nur geringem Absorptionskontrast erwiesen.
Solche Messungen können besonders gut mit monochromatischer Röntgenstrahlung
hoher räumlicher Kohärenz durchgeführt werden, wie sie bei der Synchrotron-
Computertomographie (SY-CT) benutzt wird. Nachteilig wirken sich allerdings die
Phasenverschiebung des Synchrotronstrahls über das Strahlprofil und damit die
Kantenverbreiterung in den zu untersuchenden Strukturen aus. Daher ist ein
dimensionelles Messen mit normalen Rekonstruktionsverfahren nicht möglich. In
der vorliegenden Arbeit werden neue Filterverfahren zur Korrektur der
Phasenverschiebung unter Beibehaltung des erhöhten Kontrastes bei der
Rekonstruktion angewandt, um ausgewählte einkomponentige Referenzobjekte
hinsichtlich der dimensionellen Messeigenschaften zu untersuchen. Als Referenz
werden rückgeführte Messungen mit taktilen Koordinatenmessmaschinen
herangezogen. Die Untersuchungen wurden im freien Strahl durch Variation des
Abstandes zwischen Objekt und Detektor am Strahlrohr der BAM am Helmholtz-
Zentrum Berlin für Materialien und Energie - Speicherring BESSY II durchgeführt.
In this paper, we focus on the role of graphs and graph transformation for four practical application areas from software system development. We present the typical problems in these areas and investigate how the respective systems are
modelled by graphs and graph transformation. In particular, we are interested in the usefulness of theoretical graph transformation results and graph transformation tools in order to solve these problems. Finally, we characterize concepts and tool features
which are still missing in practice to solve the presented and related problems even better.
Evaluating porosity in cordierite diesel particulate filter materials, part 1 X-ray refraction
(2013)
Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, with porosity and solid matter being intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using x-ray absorption and refraction, we quantitatively evaluate porosity and pore orientation in cordierite diesel particulate filter ceramics. Porosity values turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data.
Despite their enormous diversity, the bauplan of adult winged insects (pterygotes) is remarkably conservative since the Lower Devonian: a five-segmented head, a three-segmented thorax with three pairs of walking legs and an eleven-segmented abdomen without any non-sexual appendages 1 and 2. The only known exceptions are the abdominal appendages of adult male sepsid flies on the fourth segment; however, these are also used as copulatory organs and are supposedly maintained through sexual selection [3]. Here, we report a rod-like paired appendage from the third and fourth abdominal segments in adults of the Southeast-Asian Hemiptera taxon Bennini (Figure 1A,B; Supplemental information). These are fully musculated, innervated, and movable and bear highly organized sensory and secretory units. The appendages, termed LASSO (lateral abdominal sensory and secretory organs), are consistent in topology and structure in all species studied and not sexually dimorphic. The existence of these non-sexual abdominal appendages reveals the potential of the 300 million year old conserved bauplan of insects.
Biological erosion is a key process for the recycling of carbonate and the formation of calcareous sediments in the oceans. Experimental studies showed that bioerosion is subject to distinct temporal variability, but previous long-term studies were restricted to tropical waters. Here, we present results from a 14-year bioerosion experiment that was carried out along the rocky limestone coast of the island of Rhodes, Greece, in the Eastern Mediterranean Sea, in order to monitor the pace at which bioerosion affects carbonate substrate and the sequence of colonisation by bioeroding organisms. Internal macrobioerosion was visualised and quantified by micro-computed tomography and computer-algorithm-based segmentation procedures. Analysis of internal macrobioerosion traces revealed a dominance of bioeroding sponges producing eight types of characteristic Entobia cavity networks, which were matched to five different clionaid sponges by spicule identification in extracted tissue. The morphology of the entobians strongly varied depending on the species of the producing sponge, its ontogenetic stage, available space, and competition by other bioeroders. An early community developed during the first 5 years of exposure with initially very low macrobioerosion rates and was followed by an intermediate stage when sponges formed large and more diverse entobians and bioerosion rates in-creased. After 14 years, 30 % of the block volumes were occupied by boring sponges, yielding maximum bioerosion rates of 900 g m.
Complementary to Part 1 of this work, the bi-continuous microstructure of porous synthetic cordierite ceramics for filtration applications was investigated using 3D x-ray computed tomography at different resolutions. Applying both Fast Fourier Transform and a newly developed image analysis algorithm, we quantitatively evaluated porosity and pore orientation. The statistical approach allows extraction of spatially resolved or average values. Porosity values based on x-ray absorption agree with mercury intrusion measurements, while pore orientation factors agree with x-ray refraction data (Part 1 of this work), and with published crystallographic texture data.
The effects of refraction (phase-contrast) are normally considered as disturbances in high-resolution μCT-measurements. We show that in the case of small objects with low absorption a single-distance phase-retrieval algorithm not only reduces the edge enhancement, but also raises the signal-to-noise ratio sufficiently to allow dimensional measurements. This is exemplified at an optical element for optical fibre connectors.
Active thermography is an efficient non-destructive testing method for investigating the internal structure of larger carbon fiber reinforced plastic (CFRP) components as well as smaller CFRP components in mass customization. The method can be applied contactless and automated. This study contains systematic investigations of CFRP structures with typical defects and inhomogeneities occurring during production by means of flash thermography in reflection and transmission configuration and by computed tomography (CT). The latter one was used as a reference method, since also very small defects at larger depth can be visualized with high spatial resolution. The CFRP structures consist of plates which contain metallic and non-metallic inclusions, contaminations with glue or wax rests, areas with inhomogeneous re-injection of dry parts, fiber misalignments, and fiber damages. Further on, two specimens have been glued together with different artificial inhomogeneities of the four glue beads. The results of the applied methods are compared and the advantages and disadvantages of each configuration are discussed based on the detectability of the inhomogeneities. It is shown that although CT has led to best contrasts and spatial resolutions in displaying the inhomogeneities and inclusions, flash thermography is very well suited to detect most of these structures. Considering that flash thermography can be applied on-site and has a high potential for automation and for a fast and efficient testing, it can be highly recommended for quality assurance during and after production of CFRP structures.
The combination of tomographic, microstructural data with other experimental techniques and with modeling is paramount, if we want to extract the maximum amount of information on material and component properties. In particular, quantitative image analysis, statistical approaches, direct discretization of tomographic reconstructions represent concrete possibilities to extend the power of the tomographic 3D representation to insights into the material and component performance. This logic thread holds equally for industrial and academic research, and valorizes expensive experiments such as those carried out at synchrotron sources, which cannot be daily repeated. We shall show a few examples of possible use of X-ray tomographic data for quantitative assessment of damage evolution and microstructural properties, as well as for non-destructive testing. We will also show how X-ray refraction computed tomography (CT) can be highly complementary to classic absorption CT, being sensitive to internal interfaces.
Bikontinuierliche poröse Keramiken für Filteranwendungen weisen eine komplizierte Mikrostruktur auf, in der Poren und Festkörperphase 'vermischt' sind. Mechanische, thermische sowie Filtereigenschaften können nur präzise bestimmt werden, wenn die Morphologie beider Phasen quantitativ angegeben werden kann. Hier werden unter Anwendung von 3D Computertomographie (CT) und verschiedenen Techniken, die auf der Röntgenrefraktion basieren, die Porosität und die Porenorientierung in keramischen Cordierit-Dieselpartikelfiltern bewertet. Dabei werden zur Auswertung der Tomogramme die Fouriertransformierten sowie eine neu entwickelte richtungssensitive Bildanalyse (DIVA, directional interface variance analysis) angewandt. Sowohl die genannten Messtechniken als auch der statistische Ansatz gestatten die Extraktion optional ortsaufgelöster oder gemittelter Werte. Es ergeben sich sehr gute Übereinstimmungen der experimentell ermittelten Porositätswerte mit Ergebnissen aus Quecksilberintrusionsversuchen als auch der ermittelten Porenorientierung im Vergleich zu publizierten Angaben zur kristallographischen Textur. Dies legt den Schluss nahe, dass die Kenntnis der Grenzflächen (zwischen Poren und Materie) genügt, die morphologischen Eigenschaften solcher Materialien hinreichend zu beschreiben.
Bi-continuous porous ceramics for filtration applications possess a particularly complicated microstructure, whereby porosity and solid matter are intermingled. Mechanical, thermal, and filtration properties can only be precisely estimated if the morphology of both solid matter and porosity can be quantitatively determined. Using 3D computed tomography (CT) at different resolutions, and several X-ray refraction-based techniques, we quantitatively evaluated porosity and pore orientation in cordierite diesel particulate filter ceramics.Moreover, applying both Fast Fourier Transform (FFT) and a newly developed image analysis algorithm (directional interface variance analysis, DIVA), we quantitatively evaluated porosity and pore orientation. Both the experimental techniques and the statistical approach allow extraction of spatially resolved or average values.Porosity values from synchrotron computed tomography used turn out to agree with mercury intrusion measurements, while pore orientation factors agree with published crystallographic texture data. This latter point also implies that the study of the pore/matter interface is sufficient to describe the morphological properties of these materials.
In order to extend the lifetime of buildings and constructions at the macro scale it is necessary to understand the damage processes of building materials at the micro scale. In particular, durability of reinforced concrete structures is one of the most important equirements for construction planning and restoration of buildings. Therefore degradation mechanisms were reproduced on laboratory specimens.
CT (Computed Tomography) is commonly used for non-destructive microstructural defect analysis for recurring tests on concrete specimens. In this work a few examples of CT applications on cementitious materials (including cement paste, mortar and concrete specimens) will be presented.
Firstly, in order to quantify the degradation processes, specimens analysed were damaged by corrosion due to carbonation and due to chloride ingress. Particular focus has been set to the analysis of cracks.
An automated crack detection tool, developed by Zuse Institut Berlin (ZIB) and BAM in ZIBAmira, has been applied for quantitative analysis of crack parameters and 3D visualization of cracks.
Furthermore the distribution of corrosion products has been evaluated inside the cement matrix and visualized in 3D data sets.
Another important factor for the ageing stability of concrete is the interfacial transition zone (ITZ). The ITZ consists of a layer of cement paste (20 to 40 μm) over every aggregate where porosity is generally increased in comparison with the bulk. This zone could be a preferential zone for transfer of aggressive species. To visualize the ITZ, a small sample of mortar with a diameter of 10mm has been prepared and scanned using the industrial μCT setup at BAM with a spatial resolution of 5μm voxel size. In addition the extracted surface of aggregates could be used for load simulations. We finally show how CT examination of drilled samples taken from building materials in conjunction with laboratory experiments is helpful for further evaluations of damage processes in concrete.
This poster presentation gives an overview of the great potential of X-ray micro computed tomography (CT) to cast light on the evolution of the microstructure in construction materials. Prevention of damage is of major economic and social importance in the development of suitable construction materials such as concrete and asphalt. Therefore a non-destructive testing method such as CT is an appropriate tool for visualization of the inner structure. Its combination with other test methods allows understanding the damage processes such as crack propagation or corrosion. We show examples of internal structure analyses on a wide range of materials: Automatic 3D crack detection and the visualization of corrosion products inside of steel reinforced concrete, pore and shape analysis of lightweight aggregates and the visualization of deformation of high-pressure loaded aerated concrete specimens, distribution of aggregates inside concrete, and determination of the surface of porous asphalt core samples. Segmented structures serve, e.g., as input data for simulation of transport phenomena or virtual load tests.
We present a modified aluminium casting which is especially suited as test piece for measuring casting defects and the geometry by means of cone-beam micro-focus X-ray systems, and which may become a reference standard for dimensional measurements and defect detection.
To obtain a test piece with inner geometries measured by tactile means, we divided a small aluminium cylinder head into four pieces in such a way that most inner surfaces can be reached with a tactile probe. Reference geometries (spheres and cylinders) were applied to define a coordinate system for aligning the measurements in the disassembled and re-assembled state. The four pieces were re-assembled after the tactile measurement.
The test piece also contains casting defects. In order to be able to use the assembled cylinder head as reference sample for defect detection, measurements with higher spatial resolution and better signal-to-noise ratio were performed on the single parts. For improving the reliability of the reference measurements, CT measurements of each part were carried out in three different orientations, and the individual defect detections were combined to obtain a reference data set with a high probability of defect detection and a low rate of erroneous detections.
A new method for comparing the defect detection in a CT measurement to a reference data set is demonstrated, which provides individual information on every detected flaw.
We discuss the results of measurements in the assembled state with respect to the reference data for flaw detection.
Visual modeling languages for discrete behavior modeling allow the modeler to describe how systems develop over time during system runs. Models of these languages are the basis for simulation with the purpose to validate the model with respect to its requirements. Graph transformation systems have shown to be suitable for the definition of various kinds of visual modeling languages. They define a modelpsilas operational semantics as the set of all transformations of a model which are specified by graph transformation rules. For automatic simulation, rules have to be structured to control their application order. During simulation, the state changes after each rule application should be visualized in the concrete syntax of the modeling language. In this paper, we propose a generic approach to specify simulation environments based on a modelpsilas concrete syntax definition and suitable rule structuring techniques. We implement our approach using TIGER, a tool for defining visual languages based on graph transformation, and generate the specified simulation environment as plug-in for ECLIPSE. We demonstrate our approach by a case study for automatic simulation of Rubikpsilas Clock, a mechanical two-sided puzzle of clocks controlled by rotating wheels.
Aktive Thermografieverfahren werden immer häufiger zur zerstörungsfreien Prüfung von Faserverbundwerkstoffen eingesetzt, da diese völlig berührungslos arbeiten und sowohl zur Prüfung großflächiger Strukturen als auch von großen Stückzahlen kleinerer Komponenten in der Fertigung eingesetzt werden können. Dieser Beitrag beschäftigt sich mit Untersuchungen an typischen Defekten und Inhomogenitäten, die bereits während der Fertigung von CFK Bauteilen entstehen oder unbeabsichtigt mit eingebaut werden. Systematische Untersuchungen wurden mit Blitzthermografie in Reflexions- und Transmissionskonfiguration und mit Computertomographie (CT) durchgeführt. Die CT wurde dabei als Referenzverfahren genutzt, da dieses Verfahren auch kleinere Defekte mit relativ hoher Ortsauflösung und unabhängig von der Tiefe darstellen kann.
In civil engineering, the corrosion of steel reinforcements in structural elements of concrete bares a risk of stability-reduction, mainly caused by the exposure to chlorides. 3D computed tomography (CT) reveals the inner structure of concrete and allows one to investigate the corrosion with non-destructive testing methods. To carry out such investigations, specimens with a large artificial crack and an embedded steel rebar have been manufactured. 3D CT images of those specimens were acquired in the original state. Subsequently three cycles of electrochemical pre-damaging together with CT imaging were applied. These time series have been evaluated by means of image processing algorithms to segment and quantify the corrosion products. Visualization of the results supports the understanding of how corrosion propagates into cracks and pores. Furthermore, pitting of structural elements can be seen without dismantling. In this work, several image processing and visualization techniques are presented that have turned out to be particularly effective for the visualization and segmentation of corrosion products. Their combination to a workflow for corrosion analysis is the main contribution of this work.
Auswirkungen von Ermüdungsbeanspruchungen auf Struktur und Eigenschaften von Fahrbahndeckenbeton
(2015)
Ausgehend von der Zielsetzung der DFG-Forschergruppe 1498, die Einflüsse auf den AKR-Schädigungsprozess in Fahrbahndecken aus Beton grundlegend zu klären, sind zwei aufeinander aufbauende Untersuchungsschwerpunkte Gegenstand dieses Beitrags. Im ersten Schwerpunkt wurden die prüftechnischen Voraussetzungen für die Charakterisierung der Degradation und damit der Rissbildung im Fahrbahndeckenbeton durch die Vorschädigung infolge von Ermüdungsbeanspruchungen geschaffen. Realisiert wurde dies durch die Implementierung und Optimierung eines Monitoringsystems im zyklischen 4-Punkt-Biegeversuch zur simultanen Erfassung der Rissbildung im großformatigen Schwingbalken. Zusätzlich wurde die Röntgen-3D-Computertomografie für die hochauflösende räumliche quantitative Rissanalyse in den Bohrkernen aus den Schwingbalken ohne und mit Vorschädigung weiterentwickelt. Im zweiten Untersuchungsschwerpunkt wurde mittels vielfältiger Experimente an kleinformatigen Probekörpern aus dem Schwingbalken gezeigt, dass durch die Ermüdungsbeanspruchung die bruchmechanischen Materialkennwerte des Betons zum Teil eine signifikante Veränderung erfahren. Based on the objective of the DFG (German research foundation) funded research group 1498 to clarify the influences on the ASR damage process, this paper deals with two focuses of investigation. In the first focus the technical requirements for the characterisation concerning the degradation and the formation of cracks in concrete pavements by the pre-damage as a result of fatigue loading were created. This was realized by the implementation and the optimisation of a monitoring system in the cyclic four point bending test to capture simultaneously the formation of cracks in the beam under sinusoidal bending load. In addition, the X-ray 3D-computed tomography was enhanced for the high-resolution quantitative spatial crack analysis in the drilling cores extracted of the beam under sinusoidal bending load without and with a pre-damage. Building on the first focus, in the second focus of investigation a significant change of the fracture-mechanical properties of the concrete as a result of fatigue loading has been demonstrated in numerous experiments using small specimens extracted from the beam under sinusoidal bending load.
Durch die Alkalität des Betons wird Betonstahl dauerhaft vor Korrosion geschützt. Infolge von Chlorideintrag kann dieser Schutz nicht länger aufrechterhalten werden und führt zu Lochkorrosion. Die zerstörungsfreie Prüfung von Stahlbetonproben mit 3D-CT bietet die Möglichkeit, eine Probe mehrfach gezielt vorzuschädigen und den Korrosionsfortschritt zu untersuchen. Zur Quanti-fizierung des Schädigungsgrades müssen die bei dieser Untersuchung anfallenden großen Bilddaten mit Bildverarbeitungsmethoden ausgewertet werden. Ein wesent-licher Schritt dabei ist die Segmentierung der Bilddaten, bei der zwischen Kor-rosionsprodukt (Rost), Betonstahl (BSt), Beton, Rissen, Poren und Umgebung unterschieden werden muss. Diese Segmentierung bildet die Grundlage für sta-tistische Untersuchungen des Schädigungsfortschritts. Hierbei sind die Änderung der BSt-Geometrie, die Zunahme von Korrosionsprodukten und deren Veränderung über die Zeit sowie ihrer räumlichen Verteilung in der Probe von Interesse. Auf-grund der Größe der CT-Bilddaten ist eine manuelle Segmentierung nicht durch-führbar, so dass automatische Verfahren unabdingbar sind. Dabei ist insbesondere die Segmentierung der Korrosionsprodukte in den Bilddaten ein schwieriges Problem. Allein aufgrund der Grauwerte ist eine Zuordnung nahezu unmöglich, denn die Grauwerte von Beton und Korrosionsprodukt unterscheiden sich kaum. Eine formbasierte Suche ist nicht offensichtlich, da die Korrosionsprodukte in Beton diffuse Formen haben.
Allerdings lässt sich Vorwissen über die Ausbreitung der Korrosionsprodukte nutzen. Sie bilden sich in räumlicher Nähe des BSt (in Bereichen vorheriger Volumenabnahme des BSt), entlang von Rissen sowie in Porenräumen, die direkt am BSt und in dessen Nahbereich liegen. Davon ausgehend wird vor der Korrosionsprodukterkennung zunächst eine BSt-Volumen-, Riss- und Porenerken-nung durchgeführt. Dieser in der Arbeit näher beschriebene Schritt erlaubt es, halb-automatisch Startpunkte (Seed Points) für die Korrosionsprodukterkennung zu finden. Weiterhin werden verschiedene in der Bildverarbeitung bekannte Algorithmen auf ihre Eignung untersucht werden.
During the last decades, X-ray (micro-)computed tomography has gained increasing attention for the description of porous skeletal and shell structures of various organism groups. However, their quantitative analysis is often hampered by the difficulty to discriminate cavities and pores within the object from the surrounding region. Herein, we test the ambient occlusion (AO) algorithm and newly implemented optimisations for the segmentation of cavities (implemented in the software Amira). The segmentation accuracy is evaluated as a function of (i) changes in the ray length input variable, and (ii) the usage of AO (scalar) field and other AO-derived (scalar) fields. The results clearly indicate that the AO field itself outperforms all other AO-derived fields in terms of segmentation accuracy and robustness against variations in the ray length input variable. The newly implemented optimisations improved the AO field-based segmentation only slightly, while the segmentations based on the AOderived fields improved considerably.
Additionally, we evaluated the potential of the AO field and AO-derived fields for the separation and classification of cavities as well as skeletal structures by comparing them with commonly used distance-map-based segmentations. For this, we tested the zooid separation within a bryozoan colony, the stereom classification of an ophiuroid tooth, the separation of bioerosion traces within a marble block and the calice (central cavity)-pore separation within a dendrophyllid coral. The obtained results clearly indicate that the ideal input field depends on the three-dimensional morphology of the object of interest. The segmentations based on the AO-derived fields often provided cavity separations and skeleton classifications that were superior to or impossible to obtain with commonly used distance-map-based segmentations. The combined usage of various AO-derived fields by supervised or unsupervised segmentation algorithms might provide a promising target for future research to further improve the results for this kind of high-end data segmentation and classification. Furthermore, the application of the developed segmentation algorithm is not restricted to X-ray (micro-)computed tomographic data but may potentially be useful for the segmentation of 3D volume data from other sources.
Die Dauerhaftigkeit von Fahrbahndeckenbetonen wird maßgebend von ihrer Mikrostruktur bestimmt. Diese erfährt durch die äußeren Einwirkungen durch Klima und Verkehr über die Nutzungsdauer eine signifikante Veränderung. Im Kontext der in den letzten Jahren verstärkt auftretenden Schadensfälle infolge der Alkali-Kieselsäure-Reaktion (AKR) im deutschen Bundesautobahnnetz stellt sich die Frage, in welchem Maße die ermüdungsinduzierte Betondegradation den Stofftransport und damit die AKR-induzierte Rissbildung begünstigt. Dabei kommt der hochauflösenden räumlichen Quantifizierung der Rissbildung eine zentrale Bedeutung zu und bildet die Basis für die Modellierung der sich überlagernden Schädigungsprozesse.
Gegenstand dieses Beitrags ist die Darstellung der Leistungsfähigkeit der 3DComputertomographie (3D-CT) bei der quantitativen Rissanalyse in Betonen ohne und mit Ermüdungsbeanspruchung. Die Untersuchungen erfolgten dabei exemplarisch an Bohrkernen, die einem großformatigen Schwingbalken entnommen wurden. Zur Erreichung einer hinreichenden Ortsauflösung gelangte dabei die Region of Interest – Technik (ROI) zum Einsatz. Die Rissauswertung erfolgte mit einem gemeinsam vom ZIB und der BAM entwickelten Softwaretool für die automatisierte Risserkennung. So erlaubt dieses eine quantitative statistische Auswertung von Rissparametern, wie z.B. Risslänge, -breite und -orientierung. Die Notwendigkeit der automatisierten Rissauswertung beruht darauf, dass die Größe des CT-Datensatzes (mehrere GB) eine vollständige manuelle Segmentierung der Risse im 3D-Raum einen unverhältnismäßigen hohen Aufwand erfordert. Eine automatische Risserkennung liefert darüber hinaus noch weitere Daten, die eine nachträgliche Bearbeitung und Analyse der Risse erst möglich macht. Rissveränderungen über der Zeit können ebenfalls visualisiert und statistisch aufbereitet werden.