Filtern
Erscheinungsjahr
- 2021 (1730) (entfernen)
Dokumenttyp
- Vortrag (708)
- Zeitschriftenartikel (599)
- Beitrag zu einem Tagungsband (151)
- Posterpräsentation (140)
- Buchkapitel (27)
- Sonstiges (21)
- Newsletter (14)
- Forschungsbericht (13)
- Forschungsdatensatz (12)
- Dissertation (9)
Sprache
- Englisch (1308)
- Deutsch (409)
- Mehrsprachig (5)
- Russisch (4)
- Tschechisch (2)
- Italienisch (1)
- Spanisch (1)
Schlagworte
- Corrosion (40)
- Additive manufacturing (39)
- Korrosion (31)
- Ultrasound (27)
- Additive Manufacturing (26)
- Hydrogen (25)
- Quantum yield (23)
- Nanomaterial (22)
- Non-destructive testing (22)
- Additive Fertigung (21)
Organisationseinheit der BAM
- 8 Zerstörungsfreie Prüfung (344)
- 6 Materialchemie (333)
- 1 Analytische Chemie; Referenzmaterialien (265)
- 7 Bauwerkssicherheit (236)
- 9 Komponentensicherheit (227)
- 5 Werkstofftechnik (167)
- 4 Material und Umwelt (154)
- 6.3 Strukturanalytik (108)
- 9.4 Integrität von Schweißverbindungen (95)
- 8.5 Röntgenbildgebung (93)
- 6.1 Oberflächen- und Dünnschichtanalyse (85)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (85)
- 2 Prozess- und Anlagensicherheit (80)
- 3 Gefahrgutumschließungen; Energiespeicher (70)
- 6.6 Physik und chemische Analytik der Polymere (68)
- 7.6 Korrosion und Korrosionsschutz (65)
- 5.1 Mikrostruktur Design und Degradation (64)
- 9.3 Schweißtechnische Fertigungsverfahren (59)
- 1.8 Umweltanalytik (53)
- 2.1 Sicherheit von Energieträgern (51)
- 1.1 Anorganische Spurenanalytik (48)
- 9.0 Abteilungsleitung und andere (47)
- 9.2 Versuchsanlagen und Prüftechnik (46)
- 1.2 Biophotonik (45)
- 1.4 Prozessanalytik (45)
- 8.3 Thermografische Verfahren (45)
- 4.1 Biologische Materialschädigung und Referenzorganismen (42)
- 7.2 Ingenieurbau (42)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (42)
- 8.0 Abteilungsleitung und andere (42)
- 6.2 Material- und Oberflächentechnologien (40)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (40)
- 5.2 Metallische Hochtemperaturwerkstoffe (38)
- 8.4 Akustische und elektromagnetische Verfahren (38)
- 4.3 Schadstofftransfer und Umwelttechnologien (36)
- 6.0 Abteilungsleitung und andere (35)
- 7.4 Baustofftechnologie (35)
- 7.1 Baustoffe (34)
- 8.6 Faseroptische Sensorik (34)
- 4.2 Material-Mikrobiom Wechselwirkungen (32)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (30)
- 1.9 Chemische und optische Sensorik (28)
- 5.4 Multimateriale Fertigungsprozesse (28)
- 4.4 Thermochemische Reststoffbehandlung und Wertstoffrückgewinnung (27)
- 6.7 Materialsynthese und Design (26)
- 9.6 Additive Fertigung metallischer Komponenten (25)
- 9.5 Tribologie und Verschleißschutz (24)
- 5.5 Materialmodellierung (23)
- 1.5 Proteinanalytik (21)
- S Qualitätsinfrastruktur (21)
- 1.6 Anorganische Referenzmaterialien (20)
- 1.7 Organische Spuren- und Lebensmittelanalytik (20)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (19)
- 1.3 Instrumentelle Analytik (18)
- 5.0 Abteilungsleitung und andere (17)
- 5.3 Polymere Verbundwerkstoffe (17)
- 3.3 Sicherheit von Transportbehältern (16)
- 3.5 Sicherheit von Gasspeichern (15)
- 5.6 Glas (14)
- 7.7 Modellierung und Simulation (14)
- 2.0 Abteilungsleitung und andere (13)
- 4.5 Kunst- und Kulturgutanalyse (13)
- 3.4 Sicherheit von Lagerbehältern (12)
- 4.0 Abteilungsleitung und andere (12)
- 7.0 Abteilungsleitung und andere (12)
- S.2 Digitalisierung der Qualitätsinfrastruktur (12)
- VP Vizepräsident (12)
- VP.1 eScience (12)
- 3.2 Gefahrguttanks und Unfallmechanik (9)
- 7.3 Brandingenieurwesen (8)
- P Präsident (8)
- 2.2 Prozesssimulation (7)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (7)
- P.0 Präsident und andere (7)
- S.1 Qualität im Prüfwesen (6)
- 2.3 Einstufung von Gefahrstoffen und -gütern (4)
- 1.0 Abteilungsleitung und andere (3)
- S.3 Ökodesign und Energieverbrauchskennzeichnung (3)
- 2.4 Prüfung und Bewertung von Explosivstoffen/Pyrotechnik (2)
- 3.0 Abteilungsleitung und andere (2)
- PST Präsidiale Stabsstelle (2)
- S.0 Abteilungsleitung und andere (1)
- Z Zentrale Dienstleistungen (1)
- Z.1 Organisation, Controlling (1)
Paper des Monats
- ja (4)
The dispersive properties of Lamb waves can be utilised for material characterisation because the frequency-wavenumber-relationship, as well as the group velocity, depend on material parameters. These dependencies make a non-destructive estimation of an elastic constant possible. This preliminary study investigates the sensitivity of dispersion curves caused by a change in elastic constants. The Scaled Boundary Finite Element Method is used to compute special dispersion curves, which show the sensitivity value of the frequency and group velocity as a colour value. This representation allows for easy identification of patterns and local effects. Two sets of dispersion curves are presented, one set for a steel plate and the other set for a plate made of a carbon fibre reinforced polymer. In general, we notice that the sensitivity often increases with the frequency and that higher-order modes seem to be more suitable for material characterisation. Moreover, specific modes respond to material changes while others are relatively unaffected, which must be taken into consideration for material characterisation.
A simplified methodology is proposed to estimate the dynamic pressures developed within partially filled cylindrical vertical tanks when subjected to earthquake-related horizontal accelerations. The total pressure at the bottom of the tank is calculated as the superposition of vertical and horizontal pressures. While the magnitude of the vertical pressure depends on the free surface height of the liquid, the horizontal pressure depends on the magnitude of the horizontal acceleration and on the diameter of the tank. The liquid free surface oscillation angle is simulated based upon the principles of the simple pendulum analogy for sloshing. The length of the pendulum, however, is set on the basis of a methodology to calculate the free sloshing frequency of partially filled containers. Such a methodology is experimentally verified in this work. The outputs of the model for full scale situations, suggest that the lateral perturbation - sloshing phenomenon (earthquake effect) can generate an increase in the total pressure of 56% above the no lateral perturbation situation, further suggesting that such an overpressure should be taken into account when designing tanks that could be potentially subjected to earthquake-related perturbations.
For reliability and safety issues of injection wells, corrosion resistance of materials used needs to be determined. Herein, representative low-cost materials, including carbon steel X70/1.8977 and low alloyed steel 1.7225, were embedded in mortar to mimic the realistic casing-mortar interface. Two types of cement were investigated: (1) Dyckerhoff Variodur commercial Portland cement, representing a highly acidic resistant cement and (2) Wollastonite, which can react with CO2 and become stable under a CO2 stream due to the carbonation process. Exposure tests were performed under 10 MPa and at 333 K in artificial aquifer fluid for up to 20 weeks, revealing crevice corrosion and uniform corrosion instead of expected pitting corrosion. To clarify the role of cement, simulated pore water was made by dispersing cement powder in aquifer fluid and used as a solution to expose steels. Surface analysis, accompanied by element mapping on exposed specimens and their crosssections, was carried out to trace the chloride intrusion and corrosion process that followed.
Geothermal brines often contain high amounts of lead and copper ions that can precipitate as native Cu and Pb as consequence of galvanic corrosion when brines react with carbon steel materials. This contribution evaluates which materials could overcome the problem of galvanic corrosion at geothermal environment.
The behavior of these materials in water containing high chloride concentration (> 100 g/L NaCl) as well as various amounts of dissolved bCl2 and/or CuCl2 was characterized by electrochemical and exposure measurements.
Both methods reveal carbon steel suffers corrosion susceptibility, accompanied by Cu◦ and/or Pb◦ precipitation on the surface. Electrochemical measurements on stainless steels result in significant difference in corrosion and repassivation potentials (Ecorr = -189 mV, Erep = 70 mV), indicating a good corrosion resistance.
Due to increasing ageing, deterioration and loading , several prestressed concrete bridges bulit in the 1950ies and 1960ies need monitoring. Recently several bridges have sucesssfully equipped with acoustic emission sensing system. BAM works together with several universities on an add onn: Active ultrasonic monitoring combined with coda wave interferometry will help to detect subtle changes and precursors fo failure earlier than other methods.
The Jack Rabbit II (JR II) chlorine field trials in 2015 and 2016 involved nine 5–20 ton releases of pressurized liquefied chlorine from a tank mounted 1 m above a broad flat desert sand surface. A model comparison study was initiated, where 17 widely-used dense-gas dispersion models were run by scientists in seven countries.
Predictions were submitted following specified formats, using specified emissions and meteorology inputs. To compare with the model predictions, sets of observations were defined for the arc-maximum 1–3 s averaged concentrations (arc max C) and for cloud widths and heights (to 20 ppm and 200 ppm contours) at distances from 0.2 to 11.0 km from the release. The initial focus is on the three field trials (1, 6, and 7) that have the highest observed concentrations and that have detailed emissions information. It is found that these models are able to satisfactorily simulate (generally within a factor of two) the observed arc max C’s and their variation with downwind distance at this flat desert site. At each downwind distance, the scatter in the arc max C predictions covers about 1 ½ orders of magnitude, but the observed arc max C is within the range of the predictions. The median of the cloud width predictions is about 50% larger than the observed value for the three trials. The median of the cloud height predictions is within about 10% of the observed value. For both cloud width and/or height, there are a few models with large (factor of 3 or higher) overpredictions. Of the 17 models, when compared to observations, there is a core group of 5 or 6 with consistently (across all three trials and all distances) less mean error and scatter in their predictions of arc max C and cloud width and height. However, as a group, the 17 models are performing adequately (using the “factor of two” rule of thumb). An important caveat is that, at the JR II desert site, chlorine deposition is minimal. At a site with vegetation and/or organic-rich soil, the effects of removal of chlorine by deposition are expected to be significant.
Natural building materials for interior fitting and refurbishment - What about indoor emissions?
(2021)
Indoor air quality can be adversely affected by emissions from building materials, consequently having a negative impact on human health and well-being. In this study, more than 30 natural building materials (earth dry boards and plasters, bio-based insulation materials, and boards made of wood, flax, reed, straw, etc.) used for interior works were investigated as to their emissions of (semi-) volatile organic compounds ((S)VOC), formaldehyde, and radon. The study focused on the emissions from complete wall build-ups as they can be used for internal Partition walls and the internal insulation of external walls. Test chambers were designed, allowing the compounds to release only from the surface of the material facing indoors under testing Parameters that were chosen to simulate model room conditions. The emission test results were evaluated using the AgBB evaluation scheme, a procedure for the health-related evaluation of construction products and currently applied for the approval of specific groups of building materials in Germany.
Seventeen out of 19 sample build-ups tested in this study would have passed this scheme since they generally proved to be low-emitting and although the combined emissions of multiple materials were tested, 50% of the measurements could be terminated before half of the total testing time.
The durability of flame retardancy is a challenge for cables over long lifetimes. The degradation of flame retardance is investigated in two kinds of exposures, artificial weathering and humidity. In this basic study, typical mineral flame retardants in two polymers frequently used in cable jackets are investigated to get the fundamental picture. Aluminum hydroxide (ATH) and magnesium hydroxide (MDH) are compared in ethylene‐vinyl acetate (EVA), and further in EVA and linear low‐density polyethylene (LLDPE) cables containing the same ATH. The changes in chemical structure at the surface are studied through attenuated total reflectance Fourier transform infrared spectroscopy (ATR‐FTIR), the formation of cracks, and changes in color are investigated. The cone calorimeter and a bench scale fire testing cable module are utilized to evaluate the fire behavior of the cables. Although the flame retardancy deteriorated slightly, it survived harsh exposure conditions for 2000 h. Compared to EVA/MDH and LLDPE/ATH, the fire behavior of EVA/ATH is the least sensitive. Taken together, all of the results converge to estimate that there will be no problem with flame retardancy performance, for materials subjected to natural exposure for several years; the durability of fire retardancy is questionable for longer periods, and thus requires further investigation.
This review summarizes recent developments regarding molecular imaging markers for magnetic resonance imaging (MRI) of prostate cancer (PCa). Currently, the clinical standard includes MR imaging using unspecific gadolinium-based contrast agents. Specific molecular probes for the diagnosis of PCa could improve the molecular characterization of the tumor in a non-invasive examination. Furthermore, molecular probes could enable targeted therapies to suppress tumor growth or reduce the tumor size.
Durch die Einbeziehung von gemessenen Daten bei der Bewertung von bestehenden Bauwerken können Unsicherheiten bei der Beurteilung des Tragverhaltens reduziert werden, ohne das normative Zuverlässigkeitsniveau einzuschränken. Informationen sind die wesentliche Grundlage für die Analyse der Zuverlässigkeit von Tragwerken. Umso wichtiger ist die Kenntnis über die Präzision und die Richtigkeit der verwendeten Informationen. Aus messtechnischer Sicht kann ein Messwert, dem keine Messunsicherheit beigeordnet wurde, als wertlos erachtet werden. Liegt ein vollständig dokumentiertes Messergebnis vor, so ist die Qualität der gemessenen Information bekannt und deren Vergleichbarkeit gewährleistet. In diesem Beitrag wird am Beispiel einer Spannbetonbrücke und zweier Grenzzustände gezeigt, wie Messergebnisse aus der zerstörungsfreien Prüfung in probabilistische Nachweise von Bestandsbauwerken einfließen können und welche Auswirkungen die Implementierung von gemessenen Daten bei der Bewertung von Bestandsbauwerken haben kann.