Ingenieurwissenschaften
Filtern
Dokumenttyp
- Vortrag (13)
- Zeitschriftenartikel (11)
- Beitrag zu einem Tagungsband (4)
- Sonstiges (2)
- Forschungsbericht (2)
- Posterpräsentation (1)
Schlagworte
- Additive Manufacturing (3)
- L-PBF (2)
- 1H NMR relaxometry (1)
- 316L (1)
- AFM (1)
- Active learning (1)
- Additive manufacturing (1)
- Adsorbed Layer (1)
- Age hardening (1)
- Aged heating oil with 10% and 20% biodiesel (1)
- Al-Mg-Si (1)
- Al‐Cu‐Li‐alloy (1)
- Antibiotics (1)
- BNP (1)
- Bayesian inverse problems (1)
- Beförderung (1)
- Biologische Bekämpfung (1)
- Biologische Schädlingsbekämpfung (1)
- Boehmite (1)
- Broadband dielectric spectroscopy (1)
- CLP-Verordnung (1)
- Carbon emission (1)
- Cement, hydration (1)
- Chemikalienrecht (1)
- Clinker reduction (1)
- Coating (1)
- Coatings (1)
- Component assessment (1)
- Composite (1)
- Composition (1)
- Computed Tomography (1)
- Core-shell (1)
- Counterface (1)
- Crack damage detection (1)
- Crack healing (1)
- Crack propagation (1)
- Craze–crack mechanism (1)
- Crop protection products (1)
- Cyclic R-Curve (1)
- Eigenspannungen (1)
- Einstufung (1)
- Elasticity (1)
- Electron spectroscopy (1)
- Environmental stress cracking (1)
- Epoxy (1)
- Explosionsgrenzen (1)
- Explosionsschutz (1)
- Explosives (1)
- Fartigue Strength (1)
- Fatigue (1)
- Fatigue Crack Growth (1)
- Ferromagnetism (1)
- Fracture toughness (1)
- Friction (1)
- Gaussian Process Regression (GPR) (1)
- Gefährliche Stoffe (1)
- Glass (1)
- Glass ceramic (1)
- Globaler Kraftfahrzeugbestand (1)
- Green house gas (1)
- Growth kinetics (1)
- Heat flow calorimetry (1)
- High-density polyethylene (1)
- Hochfester Feinkornbaustahl (1)
- Home made explosives (1)
- Hydrogen (1)
- ISO 23173 (1)
- Inconel 718 (1)
- Inertisierung (1)
- International Energy Agency (1)
- International cooperation (1)
- Internationale Energieagentur (1)
- Internationale Zusammenarbeit (1)
- Keramikfeder (1)
- Kernel average misorientation (1)
- Kleidermotten (1)
- LPBF (1)
- Langzeitstabilität (1)
- Leightweighting (1)
- Linear elastic fracture mechanics (1)
- Luminescence (1)
- MALDI-TOF MS (1)
- Magnetic nanoparticles (1)
- Magnetic properties (1)
- Materialschutz (1)
- Micobiomes (1)
- Microstructure (1)
- Modell der konstanten Flammentemperaturen (1)
- Multi‐component diffusion (1)
- Mössbauer (1)
- Nanoparticles (1)
- Nanostructures (1)
- Notified body (1)
- Number density (1)
- Parameter identification (1)
- Phase‐field modeling (1)
- Physikalische Gefahren (1)
- Pigments (1)
- Polycarbonate (1)
- Polycondensation (1)
- Polylactide (1)
- Polymer composites (1)
- Polymers (1)
- Polyvinyl alcohol (1)
- Precipitates (1)
- Process monitoring (1)
- Radioaktiv (1)
- Residual Stress (1)
- Residual stress (1)
- Resistance of polymers (1)
- Schlupfwespen (1)
- Schweißprozess (1)
- Schweißverbindung (1)
- Sensorik (1)
- Shore hardness (1)
- Spannungs-Dehnungs-Verhalten (1)
- Strahlenschutz (1)
- Stress intensity factor (1)
- Structural Integrity (1)
- Surface Analytics (1)
- Surrogate models (1)
- Synthesis (1)
- Tensile properties (1)
- Teppichkäfer (1)
- Termites (1)
- Textilmotten (1)
- Textilschutz (1)
- Texture (1)
- Thermography (1)
- Thickness (1)
- Thin films (1)
- Time over threshold (1)
- Total amout of cars in the world (1)
- Treibhausgas (1)
- UN-GHS (1)
- Volume fraction (1)
- WAAM (1)
- Wear (1)
- X-ray (1)
- X-ray refraction (1)
- XAFS (1)
- XPS (1)
- XRD (1)
- Zinc ferrite (1)
- Zulassung (1)
- bulked epoxy adhesives (1)
- magnetic saturation (1)
- micro-fillers (1)
- nano-fillers (1)
Organisationseinheit der BAM
- 6 Materialchemie (7)
- 9 Komponentensicherheit (6)
- 7 Bauwerkssicherheit (5)
- 5 Werkstofftechnik (4)
- 6.1 Oberflächen- und Dünnschichtanalyse (3)
- 6.6 Physik und chemische Analytik der Polymere (3)
- 8 Zerstörungsfreie Prüfung (3)
- 9.4 Integrität von Schweißverbindungen (3)
- 2 Prozess- und Anlagensicherheit (2)
- 3 Gefahrgutumschließungen; Energiespeicher (2)
- 5.1 Mikrostruktur Design und Degradation (2)
- 6.3 Strukturanalytik (2)
- 8.0 Abteilungsleitung und andere (2)
- 9.3 Schweißtechnische Fertigungsverfahren (2)
- 2.0 Abteilungsleitung und andere (1)
- 2.1 Sicherheit von Energieträgern (1)
- 3.2 Gefahrguttanks und Unfallmechanik (1)
- 3.3 Sicherheit von Transportbehältern (1)
- 5.3 Polymere Verbundwerkstoffe (1)
- 5.4 Multimateriale Fertigungsprozesse (1)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (1)
- 7.2 Ingenieurbau (1)
- 7.4 Baustofftechnologie (1)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (1)
- 7.6 Korrosion und Korrosionsschutz (1)
- 7.7 Modellierung und Simulation (1)
- 8.5 Röntgenbildgebung (1)
- 9.5 Tribologie und Verschleißschutz (1)
Eingeladener Vortrag
- nein (13)
We introduce a novel adaptive Gaussian Process Regression (GPR) methodology for efficient construction of surrogate models for Bayesian inverse problems with expensive forward model evaluations. An adaptive design strategy focuses on optimizing both the positioning and simulation accuracy of training data in order to reduce the computational cost of simulating training data without compromising the fidelity of the posterior distributions of parameters. The method interleaves a goal-oriented active learning algorithm selecting evaluation points and tolerances based on the expected impact on the Kullback-Leibler divergence of surrogated and true posterior with a Markov Chain Monte Carlo sampling of the posterior. The performance benefit of the adaptive approach is demonstrated for two simple test problems.
In this paper, we demonstrate the value of 1H NMR relaxometry for studying the hydration of clinker-reduced, more climate-friendly cementitious binders. The results were obtained on typical CEM I cements and sister samples containing two different reactive agricultural ashes as well as non-reactive biochars as supplementary cementitious materials. The findings prove that time-resolved NMR measurements provide valuable additional information when combined with classical heat flow calorimetry.
The crack propagation rate of environmental stress cracking was studied on high-density polyethylene compact tension specimens under static loading. Selected environmental liquids are distilled water, 2 wt% aqueous Arkopal N100 solution, and two model liquid mixtures, one based on solvents and one on detergents, representing stress cracking test liquids for commercial crop protection products. The different surface tensions and solubilities, which affect the energetic facilitation of void nucleation and craze development, are studied. Crack growth in surface-active media is strongly accelerated as the solvents induce plasticization, followed by strong blunting significantly retarding both crack initiation and crack propagation. The crack propagation rate for static load as a function of the stress intensity factor within all environments is found to follow the Paris–Erdogan law. Scanning electron micrographs of the fracture surface highlight more pronounced structures with both extensive degrees of plasticization and reduced crack propagation rate, addressing the distinct creep behavior of fibrils. Additionally, the limitations of linear elastic fracture mechanisms for visco-elastic polymers exposed to environmental liquids are discussed.
Colours, nano and surface
(2022)
The basic ideas of colours and pigments are presented. The correlation between nanomaterials and colours are explained. Different methods are presented for investigating nanoparticles and their surface. At the end a case study is presented explaining the importance of coating for the properties of nanoparticles.
Thin polymer films are of vital importance due to their low production costs and wide range of applications in sensors, electronics, and coatings. Their geometry is ideal for the study of confinement effects, specifically one-dimensional confinement, on the thermodynamic properties and segmental dynamics of polymers. For this investigation, films of PC are prepared on both glass and silica substrates to measure the dielectric and calorimetric behavior as a function of film thickness. The methodology consists of broadband dielectric spectroscopy (BDS), ellipsometry, and atomic force microscopy (AFM). Using ellipsometry, the glass transition shows an increase with decreasing film thickness. Compared to a previous investigation of PC where dilatometry was used, an increase in PC was seen, but now only at thicknesses below 20 nm. Therefore, the critical thickness of PC, where the bulk-like layer no longer percolates through the film, is dependent on the method probing the glass transition. The dielectric behavior shows a deviation from bulk behavior with decreasing film thickness, although still showing a Vogel-Fulcher-Tammann (VFT) temperature dependence for all films. The influence of the adsorbed layer on the molecular mobility was also addressed.
ISO Technical Report 23173 describes methods by which electron spectroscopies, including X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and synchrotron techniques, can be employed to calculate the Coating thicknesses and compositions of nanoparticles. The document has been developed to review and outline the current state-of-the-art for such measurements. Such analyses of core–shell nanoparticles are common within the literature, however the
methods employed are varied; the relative advantages and disadvantages of These methods, and the optimal usage of each may not be clear to the general analyst. ISO Technical Report 23173 aims to clarify the methods that are available, describe them in clear terms, exhibit examples of their use, and highlight potential issues users may face. The information provided should allow analysts of electron spectroscopy data to make clear choices regarding the appropriate analysis of electron spectroscopy data from coated nanoparticle systems and provide a basis for understanding and comparing results from different methods and systems.
L-Lactide was polymerized with tin(II)acetate, tin(II)2-ethyl hexanoate, diphenyltin dichloride and dibutyltin bis(pentafluorophenoxide) at 130 °C in bulk. When an alcohol was added as initiator, linear chains free of cycles were formed having a degree of polymerization (DP) according to the lactide/initiator (LA/In) ratio.
Analogous polymerizations in the absence of an initiator yielded high molar mass cyclic polylactides.
Quite similar results were obtained when ε-caprolactone was polymerized with or without initiator.
Several transesterification experiments were conducted at 130 °C, either with polylactide or poly(ε-caprolactone) indicating that several transesterification mechanisms are operating under conditions that do not include formation of cycles by back-biting. Furthermore, reversible polycondensations (revPOCs) with low or moderate conversions were found that did not involve any kind of cyclization. Therefore, These results demonstrate the existence of revPOCs, which do neither obey the theory of irreversible polycondensation as defined by Flory nor the hypothesis of revPOCs as defined by Jacobson and Stockmayer. A new concept encompassing any kind of revPOCs is formulated in the form of a “polycondensation triangle”.
This presentation deals with the influence of the counterface materials on the sliding behaviour of some polymer materials in hydrogen. Polyimide (PI), polyetheretherketone (PEEK) and Polytetrafluoroethylene (PTFE) materials were investigated against hardened 52100 martensitic bearing steel and 304 austenitic stainless steel with similar roughness (Ra = 0.2 μm). Results indicate that the friction and wear of PI and PEEK materials depend on the counterface material. This effect wasn’t observed for PTFE composites.
While the tribological performance of polyimide is better against 52100 in hydrogen, improved sliding behaviour of PEEK materials is observed with 304 counterface, particularly at higher sliding speed. Surface analyses of the transfer film reveal that the influence of the counterface is primarily related to the chemical nature of the steel for PI and to the thermal conductivity of the disc for PEEK materials.
Der Einsatz von Aluminiumlegierungen als Konstruktionswerkstoff hat in den letzten Jahrzehnten aufgrund seines überlegenen Festigkeits-/ Gewichtsverhältnisses zugenommen. Dabei spielen höherfeste aushärtbare Al-Mg-Si-Legierungen eine wichtige Rolle.
Dieser Beitrag konzentriert sich auf die additive Fertigung von Prinzipbauteilen aus einer Al-Mg-Si-Aluminiumlegierung mittels Wire + Arc Additive Manufacturing. Werkstoffe dieses Legierungssystems weisen eine ausgeprägte Heißrissanfälligkeit auf, weshalb das artgleiche Fügen dieser Materialien, mittels Metallschutzgasschweißen, heutzutage immer noch eine Herausforderung darstellt. Kommerzielle Al-Mg-Si-Schweißdrähte sind am Markt nicht verfügbar.
In dieser Arbeit wird die Anwendbarkeit eines neuartigen Al-Mg-Si-Schweißdrahtes mit zusätzlichen kornfeinenden Elementen für die additive Fertigung mittels MSG-Verfahren gezeigt. Dazu wird der Zusammenhang von verwendeten Prozessparametern und der resultierenden Bauteilqualität untersucht, wobei die Größe und Verteilung von Poren sowie die Kornmorphologie analysiert werden. Darüber hinaus wird der Einfluss einer T6 Wärmenachbehandlung auf die mechanischen Eigenschaften des Werkstoffes untersucht und ein Vergleich zum entsprechenden Referenzmaterial (Knetlegierung) gezogen.
Classic non-destructive fatigue crack detection methods reveal the state of the fatigue damage evolution at the moment of application, generally not under operational conditions. The here introduced crack luminescence method realizes a clear visibility of the occurred and growing crack in loaded components during operation. Different established experiments show that due to the sensitive coating a crack Formation can be detected even in early stage under the premise the crack reached the surface. The coating consists of two layers with different properties and functions. The bottom layer emits light as fluorescence under UV radiation. The top layer covers the fluorescing one and prevents the emitting of light in case of no damage at the surface. In case of surface crack occurrence, the luminescent light is clearly noticeable by visual observations and also by standard camera equipment which makes automated crack detection possible as well. It is expected that crack luminescence can increase structural safety as well as reduce costs and time for inspections and preventive maintenance.