Chemie und Prozesstechnik
Filtern
Erscheinungsjahr
- 2019 (235) (entfernen)
Dokumenttyp
- Vortrag (122)
- Beitrag zu einem Tagungsband (42)
- Zeitschriftenartikel (38)
- Posterpräsentation (26)
- Dissertation (2)
- Sonstiges (2)
- Buchkapitel (1)
- Tagungsband (Herausgeberschaft für den kompletten Band) (1)
- Forschungsdatensatz (1)
Sprache
- Englisch (138)
- Deutsch (95)
- Mehrsprachig (1)
- Russisch (1)
Schlagworte
- Ultraschall (19)
- NDT (16)
- Concrete (15)
- Ultrasound (15)
- Zerstörungsfreie Prüfung (15)
- LIBS (10)
- Human Factors (9)
- Beton (8)
- Monitoring (8)
- Additive Fertigung (7)
- Lamb waves (7)
- Rail inspection (7)
- Super resolution (7)
- Thermografie (7)
- Additive manufacturing (6)
- Chloride (6)
- Computed tomography (6)
- Eddy current testing (6)
- Laser thermography (6)
- Luftultraschall (6)
- Reliability (6)
- Simulation (6)
- Thermography (6)
- VCSEL array (6)
- Wirbelstromprüfung (6)
- ZfP (6)
- Feuchte (5)
- Joint sparsity (5)
- Radar (5)
- Scaled Boundary Finite Element Method (5)
- Structural Health Monitoring (5)
- Virtual wave (5)
- X-ray computed tomography (5)
- 1d laser (4)
- Atmospheric pressure plasma (4)
- Bauwesen (4)
- Embedded sensors (4)
- Ferroelectret (4)
- Geführte Wellen (4)
- High-power laser (4)
- Imaging (4)
- Künstliche Bewitterung (4)
- Laser array (4)
- Measurement (4)
- NMR (4)
- Non-Destructive Testing (4)
- Non-destructive testing (4)
- Nondestructive Testing (4)
- Thermoacoustics (4)
- Wirbelstrom (4)
- ZfP 4.0 (4)
- Air-coupled transducers (3)
- Artificial neural networks (3)
- Building materials (3)
- Cement (3)
- Coda wave interferometry (3)
- Concrete bridges (3)
- Datenfusion (3)
- Defect detection (3)
- Enriched finite element method (3)
- Finite element analysis (3)
- Industrielle Radiographie (3)
- Kunststoffe (3)
- Laminography (3)
- Laser Thermography (3)
- MOF (3)
- Mapping (3)
- Material moisture (3)
- Micro hollow cathode discharge (3)
- Multilayered structures (3)
- Neutronensonde (3)
- Nondestructive testing (3)
- Phased Array (3)
- Schädigung (3)
- Structural safety (3)
- Thermoakustik (3)
- Ultrasonic Guided Waves (3)
- Ultrasonic Testing (3)
- X-ray back scattering (3)
- Absorption edge tomography (2)
- Adhesive joint (2)
- Air-coupled (2)
- Air-coupled ultrasound (2)
- Axle Inspection (2)
- BAMline (2)
- Berührungsloser Ultraschall (2)
- Bildqualitätsnachweis (2)
- Brücken (2)
- CFK (2)
- CFRP (2)
- COD-AGE (2)
- Cellular polypropylene (2)
- Civil engineering (2)
- Composite (2)
- Composite-Druckgefäß (2)
- Composites (2)
- Compressed Sensing (2)
- Computed Tomography (2)
- Corresponding relative humidity (2)
- Cracks (2)
- Damage (2)
- Damage assessment (2)
- Delamination (2)
- Dimension reduction (2)
- Education (2)
- Elektretwandler (2)
- Failure Modes and Effects Analysis (2)
- Faserverbundwerkstoff (2)
- Ferroelektret (2)
- Fiber reinforced polymer (2)
- Fluidischer Oszillator (2)
- Focal spot measurement (2)
- Fourier transform (2)
- Frequenzanalyse (2)
- Full Matrix Capture (2)
- Fußboden (2)
- Geführte Ultraschallwellen (2)
- Guided Waves (2)
- HPC (2)
- High speed (2)
- Impact damage (2)
- International Institute of Welding (2)
- Luftgekoppelter Ultraschall (2)
- Mechanical strength (2)
- Messunsicherheit (2)
- Modelling (2)
- Moisture clog (2)
- Moisture transport (2)
- Multi-layered system (2)
- Nonlinear (2)
- POD (2)
- Phased array probes (2)
- Photon counting detector (2)
- Plasma (2)
- Plasma acoustics (2)
- Probability of Detection (2)
- Procedure (2)
- Pulsed thermography (2)
- Quality assurance (2)
- Radiographie (2)
- Radiographische Prüfung (2)
- Railway (2)
- Reassessment (2)
- Reference specimen (2)
- Reinforced concrete (2)
- Richtcharakteristik (2)
- Rissbildung in Stahl (2)
- SBFEM (2)
- Scaled Boundary FEM (2)
- Scaled boundary finite element method (2)
- Schallemission (2)
- Signalmerkmale (2)
- Singular stress (2)
- Spectroscopy (2)
- Sulphate (2)
- Super Resolution (2)
- Survey (2)
- Synchrotron tomography (2)
- Synthetic Aperture Focusing Technique (2)
- Total Focusing Methode (2)
- Training (2)
- VCSEL (2)
- Validation (2)
- Verschlussbauwerk (2)
- Wandlercharakterisierung (2)
- Wasserstoffspeicher (2)
- Wavefield analysis (2)
- Wellenprüfung (2)
- Wind energy (2)
- Wood (2)
- X-Ray tube (2)
- X-ray CT (2)
- X-ray reflectivity (2)
- X-ray refraction (2)
- Zuverlässigkeit (2)
- coda wave interferometry (2)
- 2D model (1)
- 3D Druck (1)
- 3D particle analysis (1)
- 3D printing (1)
- 3D visualization (1)
- 3D-Verformungsmessung (1)
- AET (1)
- ASIC (1)
- Acoustic Emission (1)
- Acoustic Emission (AE) (1)
- Acoustic Emission Monitoring (1)
- Acoustic emitter (1)
- Acoustic sensors (1)
- Acoustic-Structure Interaction (1)
- Acoustic-structure interaction (1)
- Active thermography (1)
- Additive Manufacturing (1)
- Ageing (1)
- Air coupled ultrasound (1)
- Aluminum alloy (1)
- Amplitudenverhältnisse (1)
- Analytical model (1)
- Analyzer-based imaging (1)
- Anisotropic fiber orientation (1)
- Anisotropy estimate (1)
- Arbitrary trajectories (1)
- Array (1)
- Arraysensoren (1)
- Art restauration (1)
- Artificial weathering (1)
- Atomic and molecular mapping (1)
- Ausbildung (1)
- Autocorrelation (1)
- Automobilindustrie (1)
- Autonome Systeme (1)
- Backlighting (1)
- Beam hardening (1)
- Bildqualität (1)
- Blind structured illumination (1)
- Brennfleck (1)
- Brennfleckmessung (1)
- Brückenbauwerke (1)
- Capillary suction (1)
- Cement-based materials (1)
- Chemometics (1)
- Chemometrics (1)
- Chlorid (1)
- Classification (1)
- Codawelleninterferometrie (1)
- Cold to fast neutron testing (1)
- Composite pressure vessel (1)
- Compressed sensing (1)
- Computed Radiography (1)
- Computer-Tomographie (1)
- Computertomografie (1)
- Computertomographie (1)
- Cone Shaped Phased Array (1)
- Corrosion (1)
- Crack (1)
- DGZfP-Richtlinien (1)
- DICONDE (1)
- DIRECTT (1)
- DVC (1)
- Damage characterization (1)
- Damage detection (1)
- Data Analysis (1)
- Data Processing (1)
- Data processing (1)
- Data reconstruction (1)
- Datenanalyse (1)
- Deconvolution (1)
- Deep penetration (1)
- Dickenbestimmung (1)
- Diffraction Enhanced Imaging (1)
- Diffuse dielectric barrier discharges (1)
- Digital Industrial Radiology (1)
- Digital detector array (1)
- Digitale Bildkorrelation (DVC) (1)
- Digitale Radiographie (1)
- Digitaler Filmersatz (1)
- Digitalisierung (1)
- Direktumwandelnde Detektoren (1)
- Distributed fiber optic sensors (1)
- Dual Energy Imaging (1)
- Dual energy (1)
- Dual-Energy (1)
- Dual-energy (1)
- Eddy current (1)
- Eexisting structures (1)
- Eingebettete Sensorik (1)
- Eisenbahnschienen (1)
- Electric impedance (1)
- Electrical impedance (1)
- Electrochemical deposition (ECD) (1)
- Endlager (1)
- Endlagerung (1)
- Energieauflösende Detektoren (1)
- Engineered Barrier System (EBS) (1)
- Evaluation (1)
- Evaporative drying (1)
- Existing bridges (1)
- FEM (1)
- Faseropische Sensorik (1)
- Faseroptische Sensorik (1)
- Faserverbundwerkstoffe (1)
- Faserverstärkter Beton (FRC) (1)
- Fatigue (1)
- Feuchtigkeitsmessung (1)
- Fiber Bragg grating (FBG) (1)
- Fiber optic sensing (1)
- Fiber-reinforced concrete (1)
- Fibre Orientation Analysis (1)
- Fibre-Reinforced Concrete (FRC) (1)
- Filmersatz (1)
- Filtered back projection (1)
- Finite-element analysis (1)
- Fire Performance (1)
- Flat bottom holes (1)
- Flow Chemistry (1)
- Fluidic oscillator (1)
- Fluidische Anregung (1)
- Fluidische Oszillatoren (1)
- Flüssigwasser (1)
- Foundation (1)
- Frequenzmodulation (1)
- GFRP (1)
- GMR (1)
- GMR-Sensoren (1)
- Gas discharges (1)
- General Assembly (1)
- Giant magneto resistance (1)
- Glass paints (1)
- Guided waves (1)
- Guss (1)
- Heat diffusion (1)
- Heißluftquelle (1)
- Heterogeneous material (1)
- High Speed Testing (1)
- High resolution (1)
- Higher order FEM (1)
- Hollow Axle Inspection (1)
- Hydrogen storage (1)
- Hygrometrie (1)
- Image Processing (1)
- Image processing (1)
- Impakt-Schaden (1)
- Implant (1)
- Implants (1)
- In-situ Prüfverfahren (1)
- In-situ testing (1)
- Industrie 4.0 (1)
- Inline NMR Spectroscopy (1)
- Integrated Processes (1)
- Integrity testing (1)
- Interdigital Transducer (1)
- Inverse analysis (1)
- Irradiation (1)
- Joints (1)
- KDA Training (1)
- Kalziumsilikat (1)
- Keramik (1)
- Kirchhoff (1)
- Klassifizierung (1)
- Kohlenstofffaserverstärkter Kunststoff (1)
- Kontaktloses Impakt-Echo (1)
- Koordinatenmessung (1)
- Korrosion (1)
- Kotakttechnik (1)
- LAUS (Large Apertur Ultrasonic System) (1)
- Laminographie (1)
- Large Aperture Ultrasonic System (LAUS) (1)
- Laser (1)
- Laser Metal Deposition (LMD) (1)
- Laser powder bed fusion (1)
- Laser-Doppler-Vibrometer (1)
- Laser-Thermografie (1)
- Laser-induced breakdown spectroscopy (LIBS) (1)
- Laserthermografie (1)
- Lehrplan (1)
- Lehrplan Universität (1)
- Luftgekoppelt (1)
- MAPOD (1)
- MFC (1)
- MMI (1)
- Machine Learning (1)
- Magnetfeldsensoren (1)
- Magnetoresistive sensor (1)
- Maschinelles Lernen (1)
- Matrix array (1)
- Mechanical properties (1)
- Mechanisierte Schienenprüfung (1)
- Mehrfachreflexion (1)
- Metal Magnetic Memory (1)
- Metal matrix composite (1)
- Metall-Matrix-Komposit (1)
- Metrology (1)
- Microstructural analysis (1)
- Mikro-Computertomographie (1)
- Mikropartikel (1)
- Mobile Plattform (1)
- Mobile system (1)
- Modular Production (1)
- Morsleben Repository (ERAM) (1)
- Multiple Lineare Regression (1)
- Multivariate calibration (1)
- NDE (1)
- NDT 4.0 (1)
- NDT Monitoring (1)
- NMR relaxometry (1)
- Nachrechnung (1)
- Nachrechnungsrichtlinie (1)
- Natural gas (1)
- Neutron Imaging (1)
- Neutron imaging (1)
- Non-invasive glucose sensing (1)
- Nondestructive tesing (1)
- Normung (1)
- Notches (1)
- Nuclear Structures (1)
- Nuklear magnetische Resonanz (1)
- Numerical Modelling (1)
- Numerical modelling (1)
- Numerical simulation (1)
- On-site (1)
- Online monitoring (1)
- Onlinemonitoring (1)
- Ontology (1)
- Opaque materials (1)
- Optical fibers (1)
- PVDF (1)
- Paper watermark (1)
- Part geometry (1)
- Part material (1)
- Partial volume effect (1)
- Partiallly saturated pores (1)
- Partially saturated pores (1)
- Personalzertifizierung (1)
- Personnel Education (1)
- Phased array (1)
- Photon Counting Detectors (1)
- Photon counting detectors (1)
- Photonenzählende Detektoren (1)
- Photoplethysmography (1)
- Photothermal (1)
- Pile (1)
- Pile testing (1)
- Pipeline (1)
- Polyethylen (1)
- Polymer (1)
- Polymere (1)
- Polymers (1)
- Polypropylene Fibres (1)
- Pore size distribution (1)
- Porengrößenverteilung (1)
- Porous building materials (1)
- Porous ceramics (1)
- Porous materials (1)
- Prediction from system parameters (1)
- Pressure Vessels (1)
- Pressure tanks (1)
- Process Analytical Technology (1)
- Projection matrix (1)
- Quantenpunkte (1)
- Quantification (1)
- Quantitative moisture measurement (1)
- Quellfleckgröße (1)
- RFID based sensors (1)
- RTM (1)
- Radiation shielding (1)
- Radiografie (1)
- Radiographic Testing (1)
- Radiographic testing (1)
- Radiography (1)
- Radiography based weld inspection (1)
- Radiology (1)
- Radsatzwellen (1)
- Reaction Monitoring (1)
- Reconstruction (1)
- Refracto-vibrometry (1)
- Refraktovibrometrie (1)
- Relative Luftfeuchte (1)
- Repair patch (1)
- Requirements of Standards (1)
- Residual stress (1)
- Reverse Time Migration (RTM) (1)
- Revision of ISO 24497 (1)
- Riesenmagnetwiderstand (1)
- Roboter (1)
- Röntgenbeugung (1)
- Röntgencomputertomographie (CT) (1)
- Röntgenrefraktion (1)
- Röntgenröhre (1)
- Röntgenröhren (1)
- Röntgenrückstreuung (1)
- Salzbeton (1)
- Sandstein (1)
- Sandstone (1)
- Sandstones (1)
- Saturation (1)
- Scaled boundary finite element method; Stress intensity factors (1)
- Schaden Quantifizierung (1)
- Schichtaufbau (1)
- Schienenprüfung (1)
- Schmiedeteile (1)
- Screed (1)
- Semitransparent (1)
- Sensorik (1)
- Shaker (1)
- Signal Analysis (1)
- Spectral induced polarization (1)
- Stahlbeton (1)
- Stained glass windows (1)
- Stand der Normung (1)
- Stand der Technik (1)
- Standadization (1)
- Standardisierung (1)
- Standardisierung bei DIN, CEN und ISO (1)
- Standardization (1)
- Standards (1)
- Static Mixing (1)
- Status in Germany (1)
- Stress intensity factors (1)
- Stress singularities (1)
- Stress strain relations (1)
- Streuflussprüfung (1)
- Structural Integrity (1)
- Structural health monitoring (1)
- Structural integrity (1)
- Structure-property relationship (1)
- Structured heating (1)
- Sub-Commission V-A (1)
- Subsurface defects (1)
- Super-resolution imaging (1)
- Surface relaxivity (1)
- Surface roughness analysis (1)
- Synchrotron Radiation (1)
- TFM (1)
- THz-TD-SAFT (1)
- THz-TDS (1)
- THz-Tommographie (1)
- TRISO (1)
- Tauchtechnik (1)
- Thermal Waves (1)
- Thermal wave (1)
- Three-dimensional measurement (1)
- Thymolblau (1)
- Tomographie, (1)
- Tomography of wood samples (1)
- Transportwesen (1)
- UT-Ausbildung (1)
- UV/VIS spectroscopy (1)
- Ultraschallprüfung (1)
- Ultraschallwellen (1)
- Ultrasonic echo (1)
- Ultrasonic guided waves (1)
- Ultrasonic imaging (1)
- Ultrasonic transducers (1)
- Ultrasonic-Echo Borehole Probe (1)
- Uncertainty (1)
- Validation studies (1)
- Verschiebungsfeld (1)
- Vibrational spectroscopy (1)
- Vibrometer (1)
- Virtuelle Welle (1)
- Visibility of Indications (1)
- Vitual computer tomography simulation (1)
- Vor-Ort-Untersuchung (1)
- Vorlaufkeile (1)
- Wandler (1)
- Water layer thickness (1)
- Water transport (1)
- Wavelet transformation (1)
- Wellenausbreitung (1)
- Wirbelstromsenoren (1)
- Wood Materials (1)
- Wood materials (1)
- X-ray (1)
- X-ray Computed Tomography (CT) (1)
- X-ray Computer-tomography simulation (1)
- X-ray Radiography (1)
- X-ray caustics (1)
- X-ray computed tomography (CT) (1)
- X-ray computed tomography (XCT) (1)
- X-ray imaging (1)
- Zeitaufgelöste THz-Spektroskopie (1)
- Zerstörungsfreien Prüfung (1)
- ZfP im Bauwesen (1)
- ZfP-Ausbildung (1)
- Zugprüfungen (1)
- Zustandsüberwachung (1)
- aRTist (1)
- additive manufacturing (1)
- agricultural economy (1)
- embedded sensor (1)
- environment (1)
- fluorescence (1)
- gas analysis (1)
- pH-Monitoring (1)
- spectroscopy (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (235) (entfernen)
Eingeladener Vortrag
- nein (122)
Digital Volume Correlation (DVC) is a powerful set of techniques used to compute the local shifts of 3D images obtained, for instance, in tomographic experiments. It is utilized to analyze the geometric changes of the investigated object as well as to correct the corresponding image misalignments for further analysis. It can therefore be used to evaluate the local density changes of the same regions of the inspected specimens, which might be shifted between measurements. In recent years, various approaches and corresponding pieces of software were introduced. Accuracies for the computed shift vectors of up to about 1‰of a single voxel size have been reported. These results, however, were based either on synthetic datasets or on an unrealistic setup. In this work, we propose two simple methods to evaluate the accuracy of DVC-techniques using more realistic input data and apply them to several DVC programs. We test these methods on three materials (tuff, sandstone, and concrete) that show different contrast and structural features.
Damage Quantification in Aluminium-CFRP Composite Structures using Guided Wave Wavenumber Mapping
(2019)
The use of composite materials is associated not only with the advantages of weight reduction and improved structural performance but also with the risk of barely visible impacts or manufacturing damages. One of the promising techniques for the detection and characterisation of such damages is based on ultrasonic guided wave propagation and analysis. However, the multimodal nature and dispersive behaviour of these waves make their analysis difficult. Various signal processing techniques have been proposed for easier interpretation of guided wave signals and extraction of the necessary information about the damage. One of them is the wavenumber mapping which consists of creating a cartography of the wavenumber of a propagating mode over an inspected area, using a dense wavefield acquisition measured for example with a scanning laser Doppler vibrometer. This technique allows both the quantification of the in-plane size and the depth of damage, for example, impact-induced delamination in composite laminates.
In this contribution, wavenumber mapping is applied to a delaminated aluminium-CFRP composite structure which corresponds to composite-overwrapped pressure vessels used for storing gases in aerospace and automotive industries. The analysis of experimental data obtained from measurements of guided waves propagating in an aluminium-CFRP composite plate with impact-induced damage is performed. The output of the imaging is a three-dimensional representation of the delamination induced by the impact. Good agreement between conventional ultrasonic testing and guided wave damage mapping can be found.
Damage Quantification in Aluminium-CFRP Composite Structures using Guided Wave Wavenumber Mapping
(2019)
The use of composite materials is associated not only with the advantages of weight reduction and improved structural performance but also with the risk of barely visible impacts or manufacturing damages. One of the promising techniques for the detection and characterisation of such damages is based on ultrasonic guided wave propagation and analysis. However, the multimodal nature and dispersive behaviour of these waves make their analysis difficult. Various signal processing techniques have been proposed for easier interpretation of guided wave signals and extraction of the necessary information about the damage. One of them is the wavenumber mapping which consists of creating a cartography of the wavenumber of a propagating mode over an inspected area, using a dense wavefield acquisition measured for example with a scanning laser Doppler vibrometer. This technique allows both the quantification of the in-plane size and the depth of damage, for example, impact-induced delamination in composite laminates.
In this contribution, wavenumber mapping is applied to a delaminated aluminium-CFRP composite structure which corresponds to composite-overwrapped pressure vessels used for storing gases in aerospace and automotive industries. The analysis of experimental data obtained from measurements of guided waves propagating in an aluminium-CFRP composite plate with impact-induced damage is performed. The output of the imaging is a three-dimensional representation of the delamination induced by the impact. Good agreement between conventional ultrasonic testing and guided wave damage mapping can be found.
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
The application of phased arrays in either linear or matrix arrangement in combination with signal processing opens the door for the mechanized inspection of different thin wall materials itself as well as their joining methods.
Modern lightweight components are typically manufactured by a composition of different types of e.g. steels, metals, fiber reinforced plastics and glass. Dependent on the material combinations e.g. welding, brazing, bonding, cladding or coating may be applied during the manufacturing process to join different semi-finished products to form the component.
The resulting complex material composition and different damage mechanisms pose new challenges to non-destructive testing with ultrasound due to the different material properties and the overall arrangement of the materials employed.
The sound field variation capabilities of array probes may be helpful to overcome some of these challenges if adapted to the specific inspection task.
Examples for the non-destructive mechanized phased array inspection of different types of materials and joining methods will be presented.
This paper describes the development of a semi-automatic gas measurement device presenting potentially a broad range of applications, noteworthy in the agricultural sector. Non-reversible fluorescent molecular sensors were designed and syn-thesized. Upon, integration into a hydrogel matrix with an optimal ratio of co-solvents, the sensors reacting selectively to ammonia were illuminated by excitation light to produce a concentration-correlated fluorescence emission. An automated mechanical-elec-trical device initiates a given gas mixture and thus simulates con-centrations similar to a threshold value. The aim of this project is to develop a sensor or a low-cost method which can monitor low concentrations of harmful gases and aid in their elimination or regulation in livestock housing, barns or stables.
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.
The moisture content of screed samples is monitored by means of embedded sensors. Relative humidity sensors and multi-ring-electrodes are used to measure the spatial moisture distribution during desorption. Based on the humidity data and the pore volume distribution, the moisture and the water layer thickness within the pore space are predicted.
Slit shape as well as cylindrical pores are evaluated. Finally, the measured real part of the electrical impedance and the calculated water layer thickness are correlated. Based on the available data, a significant trend change of the impedance is documented at a water layer thickness of approximately 3 nm. This water layer thickness corresponds to a relative humidity of 88.3%.
Guided waves (GW) are of great interest for non-destructive testing (NDT) and structural health monitoring (SHM) of engineering structures such as for oil and gas pipelines, rails, aircraft components, adhesive bonds and possibly much more. Development of a technique based on GWs requires careful understanding obtained through modelling and analysis of wave propagation and mode-damage interaction due to the dispersion and multimodal character of GWs. The Scaled Boundary Finite Element Method (SBFEM) is a suitable numerical approach for this purpose allowing calculation of dispersion curves, mode shapes and GW propagation analysis. In this article, the SBFEM is used to analyse wave propagation in a plate consisting of an isotropic aluminium layer bonded as a hybrid to an anisotropic carbon fibre reinforced plastics layer. This hybrid Composite corresponds to one of those considered in a Type III composite pressure vessel used for storing gases, e.g., hydrogen in automotive and aerospace applications. The results show that most of the wave energy can be concentrated in a certain layer depending on the mode used, and by that damage present in this layer can be detected. The results obtained help to understand the wave propagation in multi-layered structures and are important for further development of NDT and SHM for Engineering structures consisting of multiple layers.
Die Verwendung von Verbundwerkstoffen ist nicht nur mit den Vorteilen einer Gewichtsreduzierung und einer verbesserten strukturellen Leistung verbunden, sondern auch mit der Gefahr von kaum sichtbaren Impakt- oder Herstellungsschäden. Eine der vielversprechenden Methoden zur Erkennung und Charakterisierung solcher Schäden basiert auf der Ausbreitung und Analyse geführter Ultraschallwellen. Der multimodale und dispersive Charakter dieser Wellen erschweren jedoch die Analyse. Verschiedene Signalverarbeitungsmethoden wurden vorgeschlagen, um die Interpretation von Signalen und die Extraktion der notwendigen Informationen über den Schaden zu erleichtern. Eine davon ist die Erstellung einer Wellenzahlkarte. Die Wellenzahlkarte erlaubt es jeden Punkt in einer hochaufgelöste Wellenfeldaufnahme eine Wellenzahl zuzuordnen. Diese Methode ermöglicht sowohl die Quantifizierung der Größe als auch der Tiefe des Schadens.
In diesem Beitrag wird diese Bildgebungsmethode auf delaminierte Aluminium-CFK-Verbundstrukturen angewendet. Solche Strukturen entsprechen den umwickelten Druckbehältern, die zur Speicherung von Gasen in der Luft- und Raumfahrt sowie in der Automobilindustrie verwendet werden. Zunächst werden die numerischen Untersuchungen zur einfachen Delamination in unterschiedlicher Tiefe vorgestellt. Als nächstes wird die Analyse von experimentellen Ergebnissen von einer geschädigten Aluminium-CFK-Platte präsentiert. Das Ergebnis der Bildgebung ist eine dreidimensionale Darstellung, die sowohl die Größe als auch die Tiefe des Impakt-Schadens liefert.
Issues that prevent Structural Health Monitoring (SHM) based on Guided Waves (GW) from being a part of today’s monitoring solutions in industry are not all obvious to the scientific community. To uncover and overcome these issues, scientists working on SHM and GW problems joined in an expert committee under the patronage of the German Society for Non-Destructive Testing. An initiated online survey among more than 700 experts and users reveals the hurdles hindering the practical application of GWbased SHM. Firstly, methods for proof of reliability of SHM approaches are missing.
Secondly, detailed understanding of phenomenological described wave-damage interactions is needed. Additionally, there are significant unsolved implementation issues and unsolved problems of signal processing including handling of environmental influences.
To enable substantial proof of reliability without unaffordable experimental effort also efficient simulation tools including realistic damage interaction are needed, enabling the joint use of experimental and simulated data to predict the capabilities of the Monitoring system. Considering these issues, the committee focusses on simulation, signal processing, as well as probability of detection and standardization. In the presented work, recent activities of the expert committee starting with survey results are summarized. An open access data basis of life-like measurements is presented to allow testing and comparison of signal processing and simulation algorithms. Finally, a strategy for efficient proof of reliability increasing the acceptance of SHM in industry and for successful Integration of SHM into real-world engineering structures is proposed.
In civil engineering, the investigation of existing infrastructure is of major importance for maintaining and ensuring stability of the structures. To ensure durability, uniform regulations and standards apply e.g. the European standard EN 206-1. In some countries, the EN-standard is supplemented by additional standards, as in Germany with DIN 1045-2. Here, specific application rules are described, e.g. for the cement type, to ensure the resistant to different exposures. Therefore, the knowledge of the materials originally used is important in assessing the condition of existing concrete structure. Unfortunately, these are often unknown and must be determined retrospectively. Therefore, we present the application of the laser-induced breakdown spectroscopy to distinguish between different types of cement. Spectral information’s are used to build a classification model. First, the accuracy of the classification is analyzed on ten pure laboratory cement samples. To investigate possible sources of error, the model was then applied to cement samples with different moisture content. The study shows that LIBS is a promising tool for distinguishing between cement types. For further industrial application, however, factors influencing the LIBS signal must be included to ensure a robust model.
Issues that prevent Structural Health Monitoring (SHM) based on Guided Waves (GW) from being a part of today’s monitoring solutions in industry are not all obvious to the scientific community. To uncover and overcome these issues, scientists working on SHM and GW problems joined in an expert committee under the patronage of the German Society for Non-Destructive Testing. An initiated online survey among more than 700 experts and users reveals the hurdles hindering the practical application of GWbased SHM. Firstly, methods for proof of reliability of SHM approaches are missing.
Secondly, detailed understanding of phenomenological described wave-damage interactions is needed. Additionally, there are significant unsolved implementation issues and unsolved problems of signal processing including handling of environmental influences.
To enable substantial proof of reliability without unaffordable experimental effort also efficient simulation tools including realistic damage interaction are needed, enabling the joint use of experimental and simulated data to predict the capabilities of the Monitoring system. Considering these issues, the committee focusses on simulation, signal processing, as well as probability of detection and standardization. In the presented work, recent activities of the expert committee starting with survey results are summarized. An open access data basis of life-like measurements is presented to allow testing and comparison of signal processing and simulation algorithms. Finally, a strategy for efficient proof of reliability increasing the acceptance of SHM in industry and for successful Integration of SHM into real-world engineering structures is proposed.
3D images such as those produces by X-ray tomography can provide a wealth of information on the internal structure of materials, but quantification of specific geometrical or topological characteristics linked to some bulk physical property is far from being straightforward. This study focuses on methods to quantify the differences in physical properties as a function of direction, i.e. their anisotropy, and how it can be linked to measures of anisotropy of the internal structure of the material. The auto-correlation function gives a similarity measure in the volume as a function of distance and direction. This is a cross-correlation of the image with itself fast to compute and relatively insensitive to noise. It is why we focus on this method to compare with the physical property of our DPF material. Diesel Particulate Filter (DPF) materials are porous ceramics that; a) can be used at very high temperatures; b) have very good thermal shock resistance; c) are inert; d) can be manufactured with tailored porosity. Their usual way of production consists of the extrusion of a slurry into the desired filter shape, with successive ceramming at high temperature. This process causes anisotropy at both microscopic and macroscopic levels.
Der Beitrag beschreibt den Aufbau und die Entwicklung einer Heißluftquelle als Wärmequelle für die aktive Thermografie. Als Ausgangspunkt wird zunächst die Quellenlage betrachtet. In der Literatur über Thermografie spielt Heißluft als Wärmequelle nur in weniger als 0,1% eine Rolle, die Ursache dafür ist nicht bekannt. Es wird vermutet, dass dieser Erwärmungsmethode unterstellt wird, sie hätte Nachteile bezüglich Homogenität der Erwärmung sowie Leistungseintrag. In einer der raren Publikationen über einen Verfahrensvergleich schnitt die Heißluft-Thermografie jedoch nicht schlechter als die Vergleichsverfahren mit optischer Anregung ab, bei gleichzeitig deutlichem Zeitgewinn und geringerem technischen Aufwand.
Danach wird der fertige Versuchsaufbau mit seinen wesentlichen Komponenten dargestellt. Der Einfluss der Geometrie der Luftaustrittsdüse auf die erreichbare Wärmeverteilung an einem flachen Blech wurde an mehreren Düsen untersucht. Hierbei erwies sich eine langgestreckte Umlenkdüse mit einer Strahlumlenkung von etwa 20° als optimal zur Erzeugung einer möglichst homogenen Erwärmung.
Ein weiterer zu optimierender Parameter war die erreichbare Schaltdynamik des Heißgasstromes. Beim schnellen Schalten großer Volumenströme treten Druckstöße mit entsprechenden Temperaturänderungen auf. Hinzu kommt, dass der verwendete MFC (mass flow controller) bei großen Volumenströmen zum Einschwingen bei Schaltprozessen neigt.
Daher enthält der Aufbau einen offenen Bypass zur Stabilisierung des Volumenstroms. Mit dem so realisierten Messplatz wurde die Reproduzierbarkeit der erzielten Erwärmung durch mehrfache Wiederholungsmessungen über einen längeren Zeitraum untersucht. Hierzu wurde ein auch zu Validierungszwecken genutzter PVC-Block mit 13 mm Dicke jeweils für 60 s erwärmt und die Oberflächentemperatur des PVC-Blocks mit einer IR-Kamera aufgezeichnet. Bei jeweiligem Neuaufbau ohne Justierhilfe ergab sich eine Reproduzierbarkeit von etwa 22% bei 5 Versuchen. Unter Nutzung einer Justierhilfe (Schablone für Abstand in der Kamerasoftware) ließ sich die Reproduzierbarkeit auf 5% bei 7 Versuchen reduzieren.
Ein weiterer zu klärender Punkt war der erzielbare Wärmeeintrag im Vergleich zu einer Anregung mit Blitzlampen. Hierzu wurde eine Messung mit 60 s Heißluftheizung direkt mit einer Evaluierungsmessung mit Blitzlampen am gleichen PVC-Probekörper mit 4 FBB an der Rückseite verglichen. Die Inhomogenität der Erwärmung wurde durch eine Phasenauswertung unterdrückt. Die Phasenauswertung gestattete den Nachweis aller 4 FBB, wobei das Signal zu Rausch-Verhältnis bei der Heißlufterwärmung deutlich besser war. Der direkte Vergleich der Temperaturkurven zeigt, dass bei 60 s Heizlufterwärmung ca. 4,5 mal mehr Energie als bei der Blitzanregung vom Probekörper absorbiert wurde. Hieraus lässt sich die eingekoppelte Heizleistung mit 100 mW/cm² abschätzen. Das entspricht in etwa dem Niveau, wie es auch mit bewegten Halogenstrahlern, bewegten IR-Strahlern oder der Sonne erreicht wird.
Diese Ergebnisse belegen, dass eventuell vorhandene Vorbehalte gegenüber einer Heißluft als Wärmequelle für die aktive Thermografie zumindest für thermisch langsame Materialien wie Kunststoffe oder mineralische Baustoffe unbegründet sind. Die Einsatzgrenzen bei der Untersuchung thermisch schnellerer Materialien wie Metalle steht noch aus, hier ist mit Abstrichen zu rechnen. Auf der anderen Seite lässt eine mögliche Düsenoptimierung noch deutliche Verbesserungen erwarten.
Pulsed thermography is a well-known non-destructive testing technique and has proven to be a valuable tool for examination of material defects, to determine thermal material parameters, and the thickness of test specimens through calibration or mathematical models. However, the application to semitransparent materials is quite new and demanding, especially for semitransparent materials like epoxy, polyamide 12, or glass fiber reinforced polymers with epoxy or polyamide matrix.
In order to describe the temporal temperature evolution in such materials, which are recorded with an infrared camera during pulse thermography experiments, much more influences have to be considered, compared to opaque materials:
- The wavelength of the excitation source and the spectral range of the infrared camera
- The angles between the specimen, the excitation source and the infrared camera
- The area behind the specimen
- The roughness of the material surface
- The scattering mechanism within the material
Here, we will consider all these influences and describe how they can be treated mathematically in analytical or numerical models (using COMSOL Multiphysics software). These models describe the temperature development during the pulse thermography experiment in reflection and transmission configuration. By fitting the results of the mathematical models to experimental data it is possible to determine the thickness or the optical and thermal properties of the specimen.
Explosive spalling is caused by, among others, the thermohydraulic spalling mechanism. During this process, vaporization, dehydration, moisture-transport and condensation processes interact. As a result, a drying and dehydration zone as well as a saturated zone, known as a moisture clog, are observed inside the unilaterally-heated concrete. The presented research is focused on the experimental investigation of the underlying thermohydraulic processes.
To investigate these, a test methodology based on X-ray computed tomography (CT) and nuclear magnetic resonance (NMR) was developed. Thereby, the X-ray CT scans are carried out simultaneously during the application of a defined unilateral-heating regime on a specially-constructed specimen. This miniaturized specimen, equipped with a double-layer casing, reproduces the condition within a planar, unilaterally-heated building component.
A preliminary test methodology and the first experimental results were presented at the 5th International Workshop on Concrete Spalling in Borås, Sweden (2017). The contribution for the upcoming workshop presents an improved version of this test methodology and new results for a high-performance concrete (HPC) mixture exposed to temperatures up to 500 °C. Regarding the CT measurements, a higher time-resolution of 15 min was achieved and a quantification of the moisture changes was implemented. Due to an increase in signal quality of the NMR measurements, a pore-size specific moisture distribution can now be resolved. This allows to conclude about the moisture reconfiguration between small gel pores and larger interhydrate pores. Additionally, the NMR measurement are no longer limited to first 2.5 cm below the heated surface but a one-dimensional moisture distribution can now be estimated over the whole 10 cm long specimen.
The presented results demonstrate that the combination of X-ray CT and NMR measurements enables to image and quantify the thermally-induced moisture transport and reconfiguration from small gel pores up to macro pores. This provides important insights into the thermohydraulic damage mechanism and leads to a better understanding of spalling avoidance strategies, like the addition of polypropylene fibres.
Explosive spalling is caused by, among others, the thermohydraulic spalling mechanism. During this process, vaporization, dehydration, moisture-transport and condensation processes interact. As a result, a drying and dehydration zone as well as a saturated zone, known as a moisture clog, are observed inside the unilaterally-heated concrete. The presented research is focused on the experimental investigation of the underlying thermohydraulic processes.
To investigate these, a test methodology based on X-ray computed tomography (CT) and nuclear magnetic resonance (NMR) was developed. Thereby, the X-ray CT scans are carried out simultaneously during the application of a defined unilateral-heating regime on a specially-constructed specimen. This miniaturized specimen, equipped with a double-layer casing, reproduces the condition within a planar, unilaterally-heated building component.
A preliminary test methodology and the first experimental results were presented at the 5th International Workshop on Concrete Spalling in Borås, Sweden (2017). The contribution for the upcoming workshop presents an improved version of this test methodology and new results for a high-performance concrete (HPC) mixture exposed to temperatures up to 500 °C. Regarding the CT measurements, a higher time-resolution of 15 min was achieved and a quantification of the moisture changes was implemented. Due to an increase in signal quality of the NMR measurements, a pore-size specific moisture distribution can now be resolved. This allows to conclude about the moisture reconfiguration between small gel pores and larger interhydrate pores. Additionally, the NMR measurement are no longer limited to first 2.5 cm below the heated surface but a one-dimensional moisture distribution can now be estimated over the whole 10 cm long specimen.
The presented results demonstrate that the combination of X-ray CT and NMR measurements enables to image and quantify the thermally-induced moisture transport and reconfiguration from small gel pores up to macro pores. This provides important insights into the thermohydraulic damage mechanism and leads to a better understanding of spalling avoidance strategies, like the addition of polypropylene fibres.