Chemie und Prozesstechnik
Filtern
Erscheinungsjahr
- 2019 (38) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (38) (entfernen)
Schlagworte
- Thermography (3)
- Zerstörungsfreie Prüfung (3)
- Beton (2)
- Composite (2)
- Cracks (2)
- Enriched finite element method (2)
- LIBS (2)
- NDT (2)
- Nondestructive testing (2)
- Reinforced concrete (2)
- Scaled boundary finite element method (2)
- 2D model (1)
- 3D particle analysis (1)
- 3D printing (1)
- 3D visualization (1)
- AET (1)
- ASIC (1)
- Acoustic sensors (1)
- Active thermography (1)
- Additive manufacturing (1)
- Ageing (1)
- Anisotropic fiber orientation (1)
- Art restauration (1)
- Artificial neural networks (1)
- Artificial weathering (1)
- Atomic and molecular mapping (1)
- Backlighting (1)
- Bauwesen (1)
- Bildqualität (1)
- Blind structured illumination (1)
- Brücken (1)
- Building materials (1)
- CFRP (1)
- Cement (1)
- Cement-based materials (1)
- Chemometrics (1)
- Chlorid (1)
- Chloride (1)
- Civil engineering (1)
- Coda wave interferometry (1)
- Cold to fast neutron testing (1)
- Computed tomography (1)
- Concrete (1)
- Corresponding relative humidity (1)
- Corrosion (1)
- DVC (1)
- Damage detection (1)
- Data Processing (1)
- Data reconstruction (1)
- Deconvolution (1)
- Digital detector array (1)
- Digitale Radiographie (1)
- Distributed fiber optic sensors (1)
- Dual Energy Imaging (1)
- Eddy current (1)
- Eddy current testing (1)
- Electrochemical deposition (ECD) (1)
- Embedded sensors (1)
- Evaporative drying (1)
- FEM (1)
- Ferroelectret (1)
- Fiber Bragg grating (FBG) (1)
- Fiber-reinforced concrete (1)
- Finite-element analysis (1)
- Flat bottom holes (1)
- Flow Chemistry (1)
- Geführte Wellen (1)
- Heat diffusion (1)
- High resolution (1)
- Image processing (1)
- In-situ testing (1)
- Inline NMR Spectroscopy (1)
- Integrated Processes (1)
- Inverse analysis (1)
- Irradiation (1)
- Klassifizierung (1)
- Lamb waves (1)
- Laser Thermography (1)
- Laser thermography (1)
- Laser-induced breakdown spectroscopy (LIBS) (1)
- Lehrplan (1)
- MOF (1)
- Magnetoresistive sensor (1)
- Messunsicherheit (1)
- Modular Production (1)
- Multivariate calibration (1)
- NMR relaxometry (1)
- Nachrechnung (1)
- Neutron Imaging (1)
- Neutron imaging (1)
- Non-invasive glucose sensing (1)
- Notches (1)
- Numerical Modelling (1)
- Numerical modelling (1)
- Opaque materials (1)
- Optical fibers (1)
- POD (1)
- Photon Counting Detectors (1)
- Photoplethysmography (1)
- Pile testing (1)
- Polymer (1)
- Polymers (1)
- Pore size distribution (1)
- Porous building materials (1)
- Porous materials (1)
- Pressure Vessels (1)
- Process Analytical Technology (1)
- Pulsed thermography (1)
- Quantification (1)
- Quantitative moisture measurement (1)
- RFID based sensors (1)
- Radiation shielding (1)
- Radiology (1)
- Reaction Monitoring (1)
- Sandstones (1)
- Saturation (1)
- Schmiedeteile (1)
- Shaker (1)
- Singular stress (1)
- Spectral induced polarization (1)
- Spectroscopy (1)
- Standards (1)
- Static Mixing (1)
- Stress intensity factors (1)
- Stress strain relations (1)
- Structural Health Monitoring (1)
- Structural health monitoring (1)
- Structured heating (1)
- Subsurface defects (1)
- Super-resolution imaging (1)
- Surface relaxivity (1)
- Synchrotron Radiation (1)
- TRISO (1)
- Thermal wave (1)
- Three-dimensional measurement (1)
- Tomography of wood samples (1)
- UV/VIS spectroscopy (1)
- Ultraschall (1)
- Ultrasonic Testing (1)
- Ultrasonic imaging (1)
- Ultrasonic transducers (1)
- VCSEL (1)
- VCSEL array (1)
- Validation studies (1)
- Vibrational spectroscopy (1)
- Vor-Ort-Untersuchung (1)
- Water transport (1)
- Wavelet transformation (1)
- X-ray (1)
- X-ray caustics (1)
- X-ray computed tomography (CT) (1)
- X-ray computed tomography (XCT) (1)
- X-ray imaging (1)
- X-ray reflectivity (1)
- X-ray refraction (1)
- Zustandsüberwachung (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (38) (entfernen)
Der Unterausschuss „Geführte Wellen“ im Fachausschuss „Zustandsüberwachung“ der Deutschen Gesellschaft für Zerstörungsfreie Prüfung (DGZfP) hat in einer Online-Umfrage den aktuellen Stand des Einsatzes geführter Ultraschallwellen für die zerstörungsfreie Prüfung und die Strukturüberwachung (structural health monitoring) ermittelt. Es wurden deutsche und internationale Firmen und Forschungseinrichtungen befragt und mehr als 400 beantwortete Fragebögen ausgewertet.
Die Umfrageergebnisse zeigen deutlich, welche Vorteile geführte Wellen bringen, aber auch welche Probleme zu bewältigen sind, um einen breiteren Einsatz der Verfahren zu ermöglichen. Aus den Ergebnissen werden Schlussfolgerungen für die weitere Ausrichtung der Forschungs- und Entwicklungsarbeiten aber auch von Aktivitäten zur Normung und zur Bewertung der Zuverlässigkeit der Prüfverfahren abgeleitet
Dieses erste Memorandum zur Lehre und Forschung an deutschsprachigen Hochschulen auf dem Gebiet der zerstörungsfreien Prüfung im Bauwesen gibt einen Überblick hinsichtlich der akademischen Ausbildung und zeigt mögliche Schwerpunkte vor allem in der Lehre auf. Diese Schwerpunkte berücksichtigen auch aktuelle Entwicklungen und Themen auf dem Gebiet der Forschung. Es werden Anregungen zur Entwicklung bzw. Weiterentwicklung der Lehr-Curricula im Hinblick auf eine umfassende und solide fachliche Ausbildung der Studierenden des Bauwesens und angrenzender Fachrichtungen gegeben. Inhaltlich und formal lehnt sich der Beitrag an dem Memorandum der Hochschullehrer im Fachgebiet „Werkstoffe im Bauwesen“ (Breit et al., 2012) an und beruht auf einer Initiative des Unterausschusses Ausbildung – Arbeitsgruppe Ausbildung in der Hochschule – des Fachausschusses ZfP im Bauwesen der Deutschen Gesellschaft für zerstörungsfreie Prüfung (DGZfP). Die Hauptredaktion wurde übernommen von Prof. Christian U. Grosse (TU München) und Prof. Ralf W. Arndt (FH Erfurt).
Tri-structural Isotropic (TRISO)-coated particle is the fission energy source and the first safety barrier in high temperature gas-cooled reactors (HTGRs). The integrity of TRISO particle should be carefully tested before operation because the shape may affect the failure possibility of the particles, leading to increased risk of fission product release. Due to the large difference in density between the kernel and the coating layers in TRISO particles, traditional X-ray radiography cannot achieve a good image quality in terms of identifying coating layers reliably, while phase-contrast CThas the advantageof being sensitive to boundaries. This paperpresents a non-destructive test and evaluation (NDT&E) method to facilitate 3-dimensional (3D) measurement of a TRISO particle's structure, using a synchrotron phase-contrast CT. After reconstructed, the TRISO particle was rendered in a 3D space and the thickness and asphericity of the TRISO particle's layers were measured. It was found that the thickness of coating layers of the tested particle obeys Gaussian distribution. The deviation of thicknesses of the kernel and the other four layers is −2.42%, −16.32%, 26.51%, 0.98% and 7.49% compared with the design parameters. The deviation of asphericity of the kernel, IPyC and OPyC layers is −11.51%, −0.41% and 3.39%, respectively. The effect of the deviations on the temperature distribution and failure probability calculation of the particle will be investigated in the future.
In civil engineering, many structures are made of reinforced concrete. Most Degradation processes relevant to this material, e.g., corrosion, are related to an increased level of material moisture.
Therefore, moisture monitoring in reinforced concrete is regarded as a crucial method for structural health monitoring. In this study, passive radio frequency identification (RFID)-based sensors are embedded into the concrete. They are well suited for long-term operation over decades and are well protected against harsh environmental conditions. The energy supply and the data transfer of the humidity sensors are provided by RFID. The sensor casing materials are optimised to withstand the high alkaline environment in concrete, having pH values of more than 12. Membrane materials are also investigated to identify materials capable of enabling water vapour transport from the porous cement matrix to the embedded humidity sensor. By measuring the corresponding relative humidity with embedded passive RFID-based sensors, the cement hydration is monitored for 170 days.
Moreover, long-term moisture monitoring is performed for more than 1000 days. The Experiments show that embedded passive RFID-based sensors are highly suitable for long-term structural health monitoring in civil engineering.
Simulating fiber-reinforced concrete mechanical performance using CT-based fiber orientation data
(2019)
The main hindrance to realistic models of fiber-reinforced concrete (FRC) is the local materials property variation, which does not yet reliably allow simulations at the structural level. The idea presented in this paper makes use of an existing constitutive model, but resolves the problem of localized material variation through X-ray computed tomography (CT)-based pre-processing. First, a three-point bending test of a notched beam is considered, where pre-test fiber orientations are measured using CT. A numerical model is then built with the zone subjected to progressive damage, modeled using an orthotropic damage model. To each of the finite elements within this zone, a local coordinate system is assigned, with its longitudinal direction defined by local fiber orientations. Second, the parameters of the constitutive damage model are determined through inverse analysis using load-displacement data obtained from the test. These parameters are considered to clearly explain the material behavior for any arbitrary external action and fiber orientation, for the same geometrical properties and volumetric ratio of fibers. Third, the effectiveness of the resulting model is demonstrated using a second, “control” experiment. The results of the “control” experiment analyzed in this research compare well with the model results. The ultimate strength was predicted with an error of about 6%, while the work-of-load was predicted within 4%. It demonstrates the potential of this method for accurately predicting the mechanical performance of FRC components.
X-ray refraction related interaction has received rising interest since about two decades in the field of imaging, beam shaping and analysis although being discovered a century ago. Due to refraction at interfaces in inhomogeneous media X-rays undergo natural focusing (or defocusing) of waves, revealing caustics. Such Kind of intensity patterns are well-known for visible light, but have been sparsely discussed for X-rays. The Variation of irradiation density may be predicted in case of known shapes. Analogously to light optics, the intensity distributions cover several orders of magnitude including complete extinction. The partly convergent (and divergent) caustic stripes originate from narrow zones of typical size of some 10−6 of the boundary curvature radius. For the deflection of plane wave synchrotron radiation (energy in the range of some keV to some ten keV) at rods and tubes of several μm diameter, we find good Agreement between experiments and modeling by ray tracing according to Snell’s law without additional diffraction contributions. Apart from Basic Research implications, caustics may influence the performance of irradiation technologies such as sterilization or molecular cross-linking.
This paper describes a novel methodology for quantitative in-situ moisture measurement without tracking agents using X-ray computed tomography (XCT). The high levels of grey-scale precision required for the measurement of moisture without tracking agents resulted in the need for an additional image calibration procedure to correct for water-related X-ray scattering and for equipment-variability related artefacts arising during in-situ testing. This calibration procedure was developed on the basis of existing principles of XCT image cor-rection. Resulting images of moisture distribution exhibit a high level of agreement with expected material behaviour. This research demonstrated that XCT can be successfully used to measure both moisture-front movement over time and changes in 3D moisture distribution within samples. This approach to moisture measurement lays the groundwork for the planned future investigation of the interaction between cracking induced by varying chemical and mechanical processes and water transport in concrete.
Diabetes mellitus is a widespread disease with greatly rising patient numbers expected in the future, not only for industrialized countries but also for regions in the developing world. There is a need for efficient therapy, which can be via self-monitoring of blood glucose levels to provide tight glycemic control for reducing the risks of severe health complications. Advancements in diabetes technology can nowadays offer different sensor approaches, even for continuous blood glucose monitoring. Non-invasive blood glucose assays have been promised for many years and various vibrational spectroscopy-based methods of the skin are candidates for achieving this goal. Due to the small spectral signatures of the glucose hidden among a largely variable background, the largest signal-to-noise ratios and multivariate calibration are essential to provide the method applicability for self-monitoring of blood glucose. Besides multiparameter approaches, recently presented devices based on photoplethysmography with wavelengths in the visible and near-infrared range are evaluated for their potential of providing reliable blood glucose concentration predictions.
Bruchmechanische Untersuchungen werden zur Vorhersage der Lebensdauer und der Wartungszyklen benutzt. Dabei wird davon ausgegangen, dass auch Objekte ohne detektierte Anzeigen Materialfehler mit einer Reflektivität kleiner der Nachweisgrenze aufweisen können. Keine detektierte Anzeige bedeutet daher für Bauteilauslegung, dass sie eine konservative Annahme machen müssen: es wird angenommen, dass das Bauteil Materialfehler in Größe der Nachweisgrenze enthält. Dies macht die Nachweisgrenze zu dem die Lebensdauer limitierenden Faktor. Bei probabilistischen Methoden wird zusätzliches Wissen, wie Zuverlässigkeit und Fehlerauffindwahrscheinlichkeiten bei der zerstörungsfreien Prüfung mit in die Berechnung einbezogen, um zu konservative Annahmen zu vermeiden. Ziel ist es eine Model-Assisted-POD aufzubauen mit der die reale volumetrische Ultraschallprüfung großer Schmiedeteile nachgebildet werden kann. Die resultierende POD soll im Weiteren in bruchmechanischen Betrachtungen Verwendung finden. In vorangegangenen Arbeiten [Preißel2015] wurde dazu der Einfluss des Prüfrasters nach der DGZfP-Richtlinie US 07:2014 auf die Fehlerauffindwahrscheinlichkeit (parametrisch) simulativ betrachtet und die Simulationstechnik experimentell validiert. In diesem Paper werden die Ergebnisse von Preißel überprüft und um eine Prüfraster-Summen-POD, die das Szenario der realen Bauteilprüfung beschreibt, erweitert. Zudem wird eine experimentell validierte, simulative, nicht-parametrische POD für schrägliegende Defekte aufgebaut. Schließlich werden erste Untersuchungen zur Defektmorphologie vorgestellt. Diese Arbeit ist im Rahmen eines Studenten-Stipendiums der DGZfP entstanden.
Mechanochemically synthesized metal–organic Framework material HKUST-1 in combination with acrylonitrile butadiene styrene polymer was used to form a polymer metal–organic framework composite material by a simple extruder.
This composite filament was used for 3D printing. Xray diffraction measurements were used to prove the homogeneous distribution of the metal–organic framework in the polymer on a centimeter scale, whereas X-ray Absorption Edge Tomography using a synchrotron radiation source was able to evaluate the 3D distribution of the metal–organic framework material both in the filament and the resultant printed sample with a resolution of a few lm. Our very first data indicate that, apart from a few clusters having significantly higher Cu concentration, HKUST-1 is distributed homogeneously down to the 100 lm length scale in both polymer bulk materials in the form of clusters with a size of a few lm. Absorption Edge Tomography in combination with data fusion also allows for the calculation of the metal–organic framework amount located on the external polymer surface.