Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
Dokumenttyp
Sprache
- Englisch (106)
Referierte Publikation
- ja (106) (entfernen)
Schlagworte
- Additive manufacturing (33)
- Residual stress (20)
- Computed tomography (15)
- Neutron diffraction (14)
- X-ray refraction (13)
- Laser powder bed fusion (10)
- Additive Manufacturing (8)
- Creep (8)
- Microcracking (6)
- Microstructure (6)
- Ti-6Al-4V (6)
- Selective laser melting (5)
- Synchrotron X-ray diffraction (5)
- X-ray computed tomography (5)
- Computed Tomography (4)
- Synchrotron X-ray refraction radiography (4)
- AISI 316L (3)
- Ceramics (3)
- Damage (3)
- Defects (3)
- Electron beam melting (3)
- Laser Powder Bed Fusion (3)
- Metal matrix composite (3)
- Porosity (3)
- Residual Stress (3)
- Additive manufacturing (AM) (2)
- Aluminium alloys (2)
- Aluminum alloys (2)
- BAMline (2)
- Ceramic matrix composites (2)
- Chaboche model (2)
- Composite materials (2)
- Diffraction (2)
- Diffraction elastic constants (2)
- Digital Volume Correlation (2)
- Dislocations (2)
- Electron backscatter diffraction (2)
- Electron backscatter diffraction (EBSD) (2)
- Electron microscopy (2)
- Fatigue (2)
- GMR (2)
- GTN model (2)
- Hysteresis (2)
- IN718 (2)
- Lattice structures (2)
- Low carbon steel (2)
- Magnetic stray field (2)
- Metal matrix composites (2)
- Micromechanics (2)
- Microstructure and texture (2)
- Neutron Diffraction (2)
- Nonlinearity (2)
- Process atmosphere (2)
- Residual stress analysis (2)
- Residual stresses (2)
- Scanning electron microscopy (2)
- TIG-welding (2)
- Thermal expansion (2)
- Thermography (2)
- Ti-Nb alloy (2)
- X-ray diffraction (2)
- X-ray imaging (2)
- 2101 duplex stainless steel (1)
- 3D printing (1)
- 3D printing Polyamide 12 (1)
- AGIL (1)
- ANFO (1)
- Al-3.85%Mg alloy (1)
- AlSi10Mg alloy (1)
- Aluminium (1)
- Aluminum Alloys (1)
- Anisotropy (1)
- Annealing treatment (1)
- As-built LPBF IN718 alloy (1)
- Asphalt (1)
- Autocorrelation function (1)
- Average phase stress concentrations (1)
- Beta-Eucryptite (1)
- Beta-eucryptite (1)
- Binder Jetting (1)
- Biomaterials (1)
- Biomedical engineering (1)
- Bitter technique (1)
- Brittle materials (1)
- CMAS (1)
- CT (1)
- Carbon Fiber Reinforced Plastics (1)
- Cavitation (1)
- Cellular structures (1)
- Ceramic materials (1)
- Ceramic matrix composite (1)
- Ceria (1)
- Characterisation (1)
- Characterization (1)
- Cohesive finite elements (1)
- Component assessment (1)
- Composites (1)
- Concrete (1)
- Condensed Matter Physics (1)
- Contour scan strategy (1)
- Coordinate measurement machine (1)
- Cordierite (1)
- Crack detection (1)
- Crack evolution (1)
- Crack propagation (1)
- Creep deformation (1)
- Crystal Texture (1)
- Crystal structure (1)
- Crystallographic descriptor (1)
- Damage evolution (1)
- Damage tolerance (1)
- Data processing (1)
- Defect detection (1)
- Deformation (1)
- Denoising filter (1)
- Dentistry (1)
- Deviatoric (1)
- Diesel Fuel (1)
- Diesel particulates filter (1)
- Differential scheme (1)
- Diffraction Enhanced Imaging (1)
- Diffraction peak width (1)
- Diffraction-elastic constants (1)
- Dislocation-climb-controlled creep (1)
- Distortion (1)
- Distortion upon baseplate removal (1)
- Effect of scanning strategies (1)
- Effective properties (1)
- Elastic constants (1)
- Elastic-moduli (1)
- Electro-fused zirconia (1)
- Electron back-scattered diffraction (1)
- Electron backscattered diffraction (1)
- Electron beam powder bed fusion (1)
- Environment (1)
- Ernel average misorientation (KAM) (1)
- Expanding cavity model (1)
- Explosives (1)
- Extrusion (1)
- FEM (1)
- FEM Simulation (1)
- Fatigue loading (1)
- Fatigue performance (1)
- Fe2TiO5 (1)
- Fiber-reinforced composite (1)
- Fire (1)
- Fractal (1)
- Fractal Microstructure (1)
- Fractals (1)
- Fractional brownian motion (1)
- Fracture (1)
- Fracture-Toughness (1)
- GMR sensors (1)
- General Materials Science (1)
- Geometric descriptor (1)
- Glass-ceramic (1)
- Grating interferometry (1)
- Gyroid lattice (1)
- Heat treatment (1)
- Heated concrete (1)
- Helium (1)
- High Strength Concrete (1)
- High-temperature ceramics (1)
- Homogenization schemes (1)
- Hot isostatic pressing (1)
- Hybrid manufacturing (1)
- Hydrogen embrittlement (1)
- Hystersis (1)
- INCONEL 718 (1)
- Image registration (1)
- Impurity segregation (1)
- In situ alloying (1)
- In situ monitoring (1)
- In situ tensile test (1)
- In-Situ X-ray CT (1)
- In-situ Computed Tomography (1)
- In-situ Process Monitoring (1)
- In-situ neutron diffraction (1)
- Inconel 718 (1)
- Indentation (1)
- Infrared thermography (1)
- Interfacial strength (1)
- Intergranular strength (1)
- Intermetallics (1)
- Internal Surfaces (1)
- Internal stress (1)
- Inverse analysis (1)
- L-PBF IN718 material (1)
- LPBF (1)
- Laboratory X-ray diffraction (1)
- Laser methods (1)
- Laser powder bed fusion (L-PBF) (1)
- Laser powder bed fusion (LPBF) (1)
- Laser-based additive manufacturing (1)
- Lightweight structures (1)
- Load Partition (1)
- Load partition (1)
- Load transfer (1)
- L‐PBF (1)
- Macroscopic stress (1)
- Magnetic domain distribution (1)
- Material and damage behaviour (1)
- Material science (1)
- Materials Characterization (1)
- Mechanical Engineering (1)
- Mechanical behavior (1)
- Mechanicalproperties (1)
- Mechanics of Materials (1)
- Medical imaging (1)
- Melt pool monitoring (1)
- Metal Matrix Composites (1)
- Metals (1)
- Micro analysis (1)
- Microcracked ceramics (1)
- Micromechanical modeling (1)
- Microscopy (1)
- Microstructure-property relations (1)
- Modeling (1)
- Multi-phase (1)
- Nanostructured powder (1)
- Near-surface X-ray diffraction (1)
- Neutron and X-ray diffraction (1)
- Nickel-based superalloy (1)
- Nickel-based superalloys (1)
- Non-destructive Materials (1)
- Non-destructive Testing (1)
- Non-weldable superalloy (1)
- Nonlinear behavior (1)
- Nonlinear stress-strain curve (1)
- Online Monitoring (1)
- Online Process Monitoring (1)
- Optical Tomography (1)
- Orientation distribution (1)
- PBF-LB/M/316L (1)
- PE-HD Sorption (1)
- Permeability tensor (1)
- Phase grating (1)
- Phase transformation (1)
- Piston alloy (1)
- Plastic deformation (1)
- Plasticity (1)
- Polyamide 12 (1)
- Polycrystals (1)
- Pore orientation (1)
- Pores (1)
- Powder bed fusion Laser beam (1)
- Powder methods (1)
- Power law and power-law breakdown (1)
- Power-law breakdown (1)
- Precipitation (1)
- Precipitation hardening (1)
- Preferred orientation (1)
- Principal stress (1)
- Principal stress components (1)
- Process development (1)
- Process monitoring (1)
- Projekt AGIL - Alterung additiv gefertigter metallischer Materialien und Komponenten (1)
- Pure aluminium (1)
- Qquantification and segmentation (1)
- Radiography (1)
- Re-entrant surface feature (1)
- Refraction (1)
- Refractory (1)
- Representative volume element (1)
- Residual Stresses (1)
- Residual powder removal (1)
- Residual stress in AM (1)
- Residual stress state (1)
- Residual stressMultiphase compositesInteractionMicromechanical schemesAnisotropy (1)
- SLM (1)
- SSTC Model (1)
- Safety (1)
- Scaffold (1)
- Scan strategies (1)
- Scan strategy influence (1)
- Scanning transmission electron microscopy (1)
- Selective Laser Melting (1)
- Selective laser melting (SLM) (1)
- Self-organization (1)
- Si network disintegration (1)
- Sintering (1)
- Small angle neutron scattering (1)
- Solidification cracking (1)
- Solute atoms (1)
- Specific surface (1)
- Stainless Steel (1)
- Standardisation (1)
- Statistical image analysis (1)
- Statistically relevant volumes (1)
- Steady-state creep (1)
- Stiffness (1)
- Strain hardening (1)
- Strain-free lattice references (1)
- Strain-free lattice spacing (1)
- Strength (1)
- Strengthening mechanisms (1)
- Stress (1)
- Stress balance (1)
- Stress balance condition (1)
- Stress concentration tensor (1)
- Stress exponent (1)
- Stress-strain relations (1)
- Stress– strain curves (1)
- Surface area (1)
- Surface roughness (1)
- Surface roughness analysis (1)
- Synchrotron (1)
- Synchrotron CT (1)
- Synchrotron Radiation (1)
- Synchrotron X-ray CT (1)
- Synchrotron X-ray refraction (1)
- Synchrotron X‐ray refraction radiography (1)
- Synchrotron imaging (1)
- Synchrotron radiation (1)
- Synchrotron x-ray refraction radiography (SXRR) (1)
- Synchrotron, BAMline (1)
- TIG weld (1)
- TPMS structures (1)
- Talbot-Lau interferometer (1)
- Talbot-Lau interferometry (1)
- Tensile behavior (1)
- Tensile load (1)
- Tensile testing (1)
- Texture (1)
- Thermal barrier coatings (1)
- Thermal-Expansion (1)
- Thermally induced porosity (TIP) (1)
- Thermoelectrics (1)
- Ti6Al4V alloy (1)
- Tiatanium (1)
- Tomography (1)
- Triply Periodical Minimal Surface (1)
- VHCF (1)
- Viscoplastic (1)
- Visibility (1)
- WAAM (1)
- WAXS (1)
- Water migration (1)
- Wear resistance (1)
- X-Ray Refraction (1)
- X-ray CT (1)
- X-ray Diffraction (1)
- X-ray analysis (1)
- X-ray and Neutron Diffraction (1)
- X-ray and neutron diffraction (1)
- X-ray computed tomography (XCT) (1)
- X-ray computer tomography (1)
- X-ray phase contrast (1)
- X-ray reefraction (1)
- X-ray refraction radiography (1)
- XCT (1)
- Yield strength (1)
- Young's modulus (1)
- Young’s modulus (1)
- Zirconia (1)
- Zirconium (1)
- composites (1)
- infrared Thermography (1)
- metal matrix composite (1)
- multiphase composite (1)
- pure aluminum (1)
- subgrain (1)
- subgrain structure (1)
- β-eucryptite (1)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (92)
- 8.5 Röntgenbildgebung (92)
- 9 Komponentensicherheit (23)
- 5 Werkstofftechnik (19)
- 9.4 Integrität von Schweißverbindungen (17)
- 5.1 Mikrostruktur Design und Degradation (9)
- 9.6 Additive Fertigung metallischer Komponenten (9)
- 5.2 Metallische Hochtemperaturwerkstoffe (6)
- 8.0 Abteilungsleitung und andere (5)
- 5.0 Abteilungsleitung und andere (4)
Paper des Monats
- ja (1)
Young's modulus and Poisson's ratio changes due to machining in porous microcracked cordierite
(2016)
Microstructural changes in porous cordierite caused by machining were characterized using microtensile testing, X-ray computed tomography, and scanning electron microscopy. Young's moduli and Poisson's ratios were determined on similar to 215- to 380-mu m-thick machined samples by combining digital image correlation and microtensile loading. The results provide evidence for an increase in microcrack density and decrease of Young's modulus due to machining of the thin samples extracted from diesel particulate filter honeycombs. This result is in contrast to the known effect of machining on the strength distribution of bulk, monolithic ceramics.
Water migration in one-side heated concrete: 4D in-situ CT monitoring of the moisture-clog-effect
(2019)
Explosive spalling due to fire exposure in concrete structures can lead severe damage and, in the worst case, to premature component failure. For this reason, an in situ investigation of water Migration in concrete due to surface heating was undertaken.
During these experiments, a miniaturized concrete specimen within a confining and insulating double-hull was subjected to surface heating during simultaneous X-ray computed tomography (CT) scanning. Through the use of subtraction-based Image analysis techniques, it was possible to observe and quantify not only drying within areas of the concrete matrix close to the heated surface, but also the migration of moisture to both pore and matrix regions deeper within the specimen. It was also discovered that the correction of CT images for specimen deformation using DVC and variable detector performance using calibrated image filters significantly improved the quality of the results. This clearly demonstrates the potential of X-ray CT for evaluation of other rapid-density-change phenomena in concrete and other building materials.
Abstract While classically used to visualise the magnetic microstructure of functional materials (e.g., for magnetic applications), in this study, the Bitter technique was applied for the first time to visualise macroscopic deformation gradients in a polycrystalline low-carbon steel. Spherical indentation was chosen to produce a multiaxial elastic–plastic deformation state. After removing the residual imprint, the Bitter technique was applied, and macroscopic contrast differences were captured in optical microscopy. To verify this novel characterisation technique, characteristic “hemispherical” deformation zones evolving during indentation were identified using an analytical model from the field of contact mechanics. In addition, near-surface residual stresses were determined experimentally using synchrotron radiation diffraction. It is established that the magnetic domain distribution contrast provides deformation-related information: regions of different domain wall densities correspond to different “hemispherical” deformation zones (i.e., to hydrostatic core, plastic zone and elastic zone, respectively). Moreover, the transitions between these three zones correlate with characteristic features of the residual stress profiles (sign changes in the radial and local extrema in the hoop stress). These results indicate the potential of magnetic domain distribution imaging: visualising macroscopic deformation gradients in fine-grained ferromagnetic material with a significantly improved spatial resolution as compared to integral, mean value-based measurement methods.
Using SXRR to Probe the Nature of Discontinuities in SLM Additive Manufactured Inconel 718 Specimens
(2020)
The utilization of additive manufacturing (AM) to fabricate robust structural components relies on understanding the nature of internal anomalies or discontinuities, which can compromise the structural integrity. While some discontinuities in AM microstructures stem from similar mechanisms as observed in more traditional processes such as casting, others are unique to the AM process. Discontinuities in AM are challenging to detect, due to their submicron size and orientation dependency. Toward the goal of improving structural integrity, minimizing discontinuities in an AM build requires an understanding of the mechanisms of formation to mitigate their occurrence. This study utilizes various techniques to evaluate the shape, size, nature and distribution of discontinuities in AM Inconel 718, in a non-hot isostatic pressed (HIPed) as-built, non-HIPed and direct age, and HIPed with two step age samples. Non-destructive synchrotron radiation refraction and transmission radiography (SXRR) provides additional information beyond that obtained with destructive optical microscopy. SXRR was able to distinguish between voids, cracks and lack of melt in, due to its sensitivity to the orientation of the discontinuity.
The manufacturability of metallic alloys using laser-based additive manufacturing methods such as laser powder bed fusion has substantially improved within the last decade. However, local melting and solidification cause hierarchically structured and crystallographically textured microstructures possessing large residual stress. Such microstructures are not only the origin of mechanical anisotropy but also pose metrological challenges for the diffraction-based residual stress determination. Here we demonstrate the influence of the build orientation and the texture on the microstructure and consequently the mechanical anisotropy of as-built Inconel 718. For this purpose, we manufactured specimens with [001]/[011]-, [001]- and [011]/[111]-type textures along their loading direction. In addition to changes in the Young’s moduli, the differences in the crystallographic textures result in variations of the yield and ultimate tensile strengths. With this in mind, we studied the anisotropy on the micromechanical scale by subjecting the specimens to tensile loads along the different texture directions during in situ neutron diffraction experiments. In this context, the response of multiple lattice planes up to a tensile strain of 10% displayed differences in the load partitioning and the residual strain accumulation for the specimen with [011]/[111]-type texture. However, the relative behavior of the specimens possessing an [001]/[011]- and [001]-type texture remained qualitatively similar. The consequences on the metrology of residual stress determination methods are discussed.
In the present study, in-situ observation of Hot Isostatic Pressure (HIP) procedure of laser powder bed fusion manufactured Ti-6Al-4V parts was performed to quantitatively estimate the densifcation rate of the material and the infuence of the defect initial size and shape on such rate. The observations were performed in-situ using the Ultrafast Tomography Paris-Edinburgh Cell and the combination of fast phase-contrast synchrotron X-ray tomography and energy dispersive difraction. With this strategy, we could quantify how the efectiveness of HIP depends on the characteristics of a defect. Smaller defects showed a higher densifcation rate, while the defect shape did not have signifcant efect on such rate.
The triaxial distribution of the residual stress in laser powder bed fused austenitic steel 316L was determined by X-ray and neutron diffraction. The residual stress analysis results were linked to the thermal history of the specimens, which were manufactured with varying inter-layer-times and scanning velocities. A clear link between the in-process temperature of the specimens and the residual stress was found, based on in-situ monitoring data.
Electron Beam Powder Bed Fusion-manufactured (E-PBF) porous components with narrow pores or channels and rough walls or struts can be filled with trapped powder after the manufacturing process. Adequate powder removal procedures are required, especially for high-density porous structures. In the present research, sheetbased porous structures with different thicknesses based on triply periodic minimal surfaces fabricated by EPBF were subjected to different post-processing methods, including a traditional powder recovery system for EPBF, chemical etching and ultrasound vibration-assisted powder removal. Wall thickness, internal defects, microstructure and morphology features, powder distribution inside the specimens, mechanical properties and deformation modes were investigated. A powder recovery system could not remove all residual powder from dense structures. In turn, chemical etching was effective for surface morphology changes and subsurface layers elimination but not for powder removal, as it affected the wall thickness, considerably influencing the mechanical properties of the whole structure. The ultrasound vibration method was quite effective for the removal of residual powder from sheet-based TMPS structures and without a severe degradation of mechanical properties. 10.1016/j.msea.2022.144479 Ultrasound vibration also caused grain refinement.
This study reports on the stress relaxation potential of stress-relieving heat treatments for laser powder bed fused 316L. The residual stress is monitored non-destructively using neutron diffraction before and after the heat treatment. Moreover, the evolution of the microstructure is analysed using scanning electron microscopy. The results show, that a strong relaxation of the residual stress is obtained when applying a heat treatment temperature at 900°C. However, the loss of the cellular substructure needs to be considered when applying this heat treatment strategy.
The safe fatigue design of metallic components fabricated by additive manufacturing (AM) is still a largely unsolved problem. This is primarily due to (a) a significant inhomogeneity of the material properties across the component; (b) defects such as porosity and lack of fusion as well as pronounced surface roughness of the asuilt components; and (c) residual stresses, which are very often present in the as‐built parts and need to be removed by post‐fabrication treatments. Such morphological and microstructural features are very different than in conventionally manufactured parts and play a much bigger role in determining the fatigue life. The above problems require specific solutions with respect to the identification of the critical (failure) sites in AM fabricated components. Moreover, the generation of representative test specimens characterized by similar temperature cycles needs to be guaranteed if one wants to reproducibly identify the critical sites and establish fatigue assessment methods taking into account the effect of defects on crack initiation and early propagation. The latter requires fracture mechanics‐based approaches which, unlike common methodologies, cover the specific characteristics of so‐called short fatigue cracks. This paper provides a discussion of all these aspects with special focus on components manufactured by laser powder bed fusion (L‐PBF). It shows how to adapt existing solutions, identifies fields where there are still gaps, and discusses proposals for potential improvement of the damage tolerance design of L‐PBF components