Ingenieurwissenschaften und zugeordnete Tätigkeiten
Filtern
Erscheinungsjahr
- 2019 (287) (entfernen)
Dokumenttyp
- Vortrag (287) (entfernen)
Sprache
- Englisch (287) (entfernen)
Referierte Publikation
- nein (287) (entfernen)
Schlagworte
- Additive Manufacturing (29)
- Corrosion (19)
- MIC (9)
- Microstructure (9)
- Welding (9)
- Additive manufacturing (8)
- Diffraction (8)
- Surface functionalization (8)
- Magnetocaloric (7)
- Nanoparticle (7)
Organisationseinheit der BAM
- 6 Materialchemie (74)
- 9 Komponentensicherheit (66)
- 8 Zerstörungsfreie Prüfung (55)
- 5 Werkstofftechnik (51)
- 8.5 Röntgenbildgebung (35)
- 9.3 Schweißtechnische Fertigungsverfahren (33)
- 7 Bauwerkssicherheit (29)
- 6.6 Physik und chemische Analytik der Polymere (23)
- 9.4 Integrität von Schweißverbindungen (23)
- 4 Material und Umwelt (21)
- 1 Analytische Chemie; Referenzmaterialien (18)
- 6.2 Material- und Oberflächentechnologien (18)
- 5.4 Multimateriale Fertigungsprozesse (17)
- 7.6 Korrosion und Korrosionsschutz (17)
- 8.0 Abteilungsleitung und andere (16)
- 3 Gefahrgutumschließungen; Energiespeicher (14)
- 6.3 Strukturanalytik (13)
- 1.2 Biophotonik (12)
- 4.5 Kunst- und Kulturgutanalyse (11)
- 5.1 Mikrostruktur Design und Degradation (11)
- 6.1 Oberflächen- und Dünnschichtanalyse (11)
- 5.6 Glas (10)
- 9.5 Tribologie und Verschleißschutz (10)
- 2 Prozess- und Anlagensicherheit (9)
- 4.1 Biologische Materialschädigung und Referenzorganismen (8)
- 5.2 Metallische Hochtemperaturwerkstoffe (8)
- 5.3 Polymere Verbundwerkstoffe (7)
- 6.7 Materialsynthese und Design (7)
- 7.5 Technische Eigenschaften von Polymerwerkstoffen (6)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (5)
- 3.2 Gefahrguttanks und Unfallmechanik (4)
- 5.5 Materialmodellierung (4)
- 7.1 Baustoffe (4)
- 8.4 Akustische und elektromagnetische Verfahren (4)
- 9.0 Abteilungsleitung und andere (4)
- 1.9 Chemische und optische Sensorik (3)
- 2.4 Prüfung und Bewertung von Explosivstoffen/Pyrotechnik (3)
- 3.0 Abteilungsleitung und andere (3)
- 3.3 Sicherheit von Transportbehältern (3)
- 3.4 Sicherheit von Lagerbehältern (3)
- 6.0 Abteilungsleitung und andere (3)
- 8.6 Faseroptische Sensorik (3)
- 1.1 Anorganische Spurenanalytik (2)
- 2.1 Sicherheit von Energieträgern (2)
- 2.2 Prozesssimulation (2)
- 2.5 Konformitätsbewertung Explosivstoffe/Pyrotechnik (2)
- 4.2 Material-Mikrobiom Wechselwirkungen (2)
- 7.4 Baustofftechnologie (2)
- 9.2 Versuchsanlagen und Prüftechnik (2)
- 1.5 Proteinanalytik (1)
- 3.1 Sicherheit von Gefahrgutverpackungen und Batterien (1)
- 5.0 Abteilungsleitung und andere (1)
- 7.0 Abteilungsleitung und andere (1)
- 7.2 Ingenieurbau (1)
- 8.1 Sensorik, mess- und prüftechnische Verfahren (1)
- 8.2 Zerstörungsfreie Prüfmethoden für das Bauwesen (1)
- S Qualitätsinfrastruktur (1)
- S.2 Digitalisierung der Qualitätsinfrastruktur (1)
Eingeladener Vortrag
- nein (287)
At BAM, which is a federal institute for materials research and testing in Germany, it is one of our tasks to evaluate the safety of casks designed for transport and/or storage of radioactive material. This includes assessment of elastomeric seals applied in the casks. One of the aims is to identify a suitable method for estimating the service lifetime of the seals with regard to the requirements for long-term safety (40 years and more) of the containers. Therefore, we started an accelerated ageing programme with selected rubbers often used for seals (HNBR, EPDM and FKM) which are aged at four different temperatures (75 °C, 100 °C, 125 °C and 150 °C) for up to five years. In order to assess sealability, O-rings were aged in compression by 25 % (corresponding to the compression during service) between plates as well as in flanges that allow leakage rate measurements. For comparison, uncompressed O-rings were aged as well. In order to understand the underlying ageing mechanisms in each material, material properties such as hardness, density and tensile properties were examined. Additionally, compression set (CS), which represents the recovery behaviour of a seal after release from compression, is measured. For obtaining results closely related to practical conditions, O-rings with a full-scale cord diameter of 10 mm were aged. However, this set-up can lead to heterogeneous ageing caused by diffusion-limited oxidation (DLO) effects especially for HNBR, resulting in distorted bulk properties such as compression set. However, if DLO-affected data is excluded, extrapolations of CS data are possible using time-temperature shifts.
For selecting an appropriate end-of-lifetime criterion, leakage rate measurements were performed, since leakage rate is the only characteristic directly correlated to the performance of the sealing system. A significant increase in leakage rate was considered as the end of the lifetime. However, the O-rings remained leak tight under static conditions even though material properties had already degraded strongly. For this reason, a modified, more demanding leakage test involving a fast small decompression of the seal was developed that allowed determining a more conservative end-of-lifetime criterion with a safety margin for EPDM seals. FKM, which is a very heat and oxidation resistant material, exhibited only little degradation, even though it had the smallest activation energy.
At the Stakeholder meeting of the EMPIR project “Multifunctional ultrafast microprobes for on-the-machine measurements”, details about two measurement modes were presented. Force distance curves and contact resonance measurements are compared. The basic principles are explained and exemplary measurements concerning mechanical properties of polymers are shown.
High heat input leads to grain coarsening and softening in WM and HAZ; the tensile strength is reduced. Low heat input leads to inadmissible hardening in the WM; the impact strength is reduced.
The proposed t8/5-time of 3 s to 15 s could be achieved through the reduced welding velocity.
The concept of electromagnetic weld pool support system allowed single-pass welds in flat position without gravity drop-outs even for reduced welding speeds; in this way the heat input can be controlled.
The adaptation of the electromagnetic weld pool support system to laser and laser hybrid welding process can dramatically increase the potential field of application of these technologies for real industrial implementation.
Microstructure ageing of stainless steel AISI 316L manufactured by selective laser melting (SLM)
(2019)
Additive manufacturing (AM) processes, such as SLM, offer a variety of advantages compared to conventional manufacturing. Today AM parts are still comparatively less cost-effective if they are manufactured in large quantities. To make the AM parts more cost-efficient, the AM process has to be improved. It requires a good understanding of microstructure formation, microstructure-property-relations and ageing processes affected by different loads.
In this work the ageing behavior of SLM manufactured AISI 316L stainless steel is evaluated. The microstructure effected by mechanical, thermal and corrosive loads are investigated and compared to as-built microstructure. Tensile tests are used for mechanical ageing. For thermal and corrosive loads the typical application conditions of 316L apply. The methods of microstructure investigation include SEM, TEM, CT and EBSD. The main object of this work is the description of microstructure and ageing processes of AM parts.
Additive manufacturing (AM) offers diverse advantages compared to conventional manufacturing. In this work the microstructure of austenitic steel 316L, manufactured with Selective Laser Melting (SLM), was analyzed and compared to microstructure of 316L hot rolled material. Methods used for analysis are microprobe, optical microscopy and electron backscatter diffraction.
The distributed measurement of relative humidity is a sought-after capability for a wide range of applications in civil engineering and structural health monitoring. We show that polymethyl methacrylate (PMMA) optical fi-bers can be employed as a sensor medium to conduct distributed humidity measurement by analyzing Rayleigh backscattering traces obtained by OTDR. We make use of the effect that water penetrates the fiber core and directly influences the local fiber attenuation and Rayleigh backscatter coefficient. We conducted distributed backscattering analysis for two different pulse wavelengths: 500 nm and 650 nm. The 650 nm results are susceptible to both, attenuation changes and backscatter changes, whereas backscatter results at 500 nm are not affected by humidity-induced attenuation and only exhibit a change of Rayleigh backscattered power as a function of humidity. The combined measurement and analysis of both parameters at these two wavelengths has the advantage that cross-sensitivities on backscatter change and attenuation, such as strain and tempera-ture changes, could be separated from the humidity response of the fiber. We present laboratory results for a humidity range between 30% and 90% for both pulse wavelengths: including step responses, humidity cycles and hysteresis analysis. In addition to the attenuation and backscatter coefficient dependence, we also analyze optical runtime changes as a function of humidity. POFs have the advantage that they can be directly embed-ded into materials such as concrete or soil to measure water content or localize water ingress. Standard step-index PMMA POFs can be used as a distributed relative humidity sensor up to 200 m distance.
Composite pressure vessels for transporting dangerous goods and for hydrogen and natural gas vehicles consist of a load-bearing composite and a gas-tight, metallic or polymeric barrier layer (liner). To investigate the aging behavior of such composite pressure vessels, BAM carried out the interdisciplinary project COD-AGE. The aim of the project was the development of methods and models for the description and determination of the aging behavior of carbon fiber composites using the example of pressure vessels in order to better predict aging and safe working life. One focus of this project was the provision of suitable NDT methods. These included both test-related tests and the possible development of test equipment for later practical use.
In the lecture, test results of the age-related eddy current test on composite pressure vessels are presented.
In aging tests, pressure vessels made of an approximately 4 mm thick aluminum liner and approx. 8 mm thick CFRP layer were examined. Typical application of such pressure vessels are respiratory protective devices of the fire department. The pressure vessels were tested using conventional eddy current technology from the outer and inner side as well as with high-frequency eddy current technology. Both damage to the metallic liner and structures of the CFRP could be detected. A particular mechanical challenge was the inspection of the inside of the liners, since a cylindrical surface with an inside diameter of 150 mm has to be tested with an access of only 15 mm diameter.