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- Reliability (3)
- POD (2)
- Acetylendruckgasbehälter (1)
- Aufheizverhalten (1)
- Austenitic Stainless Steel (1)
- Brandsimulation (1)
- C-scan (1)
- CFD Simulation (1)
- CFD-Modellierung (1)
- Capability evaluation (1)
High strength structural steels are susceptible to hydrogen embrittlement. A critical combination of stress, amount of diffusible hydrogen and microstructure is believed to cause cold cracking. Especially during welding of high strength structural steels high tensile residual stresses may develop. Therefore, a feasibility study was conducted using synchrotron X-ray diffraction in order to analyze the stress–strain behavior during tensile loading. For that purpose two types of steel showing different hardening mechanisms were used. On the one hand a thermo-mechanically treated S1100MC and on the other hand a quenched and tempered S1300Q were chosen. The samples were electrochemically charged with hydrogen and subsequently stored in liquid nitrogen to prevent effusion. Tensile tests of the samples were conducted in a special load frame allowing for tilting the samples while applying constant loads. High energy synchrotron radiation was used for energy dispersive X-ray diffraction (EDXRD) analysis in transmission geometry. This method offers the possibility for measuring several diffraction lines of all contributing crystalline phases of the material. Strains as well as stresses applying the sin²ψ-method were determined for varying load situations. This feasibility study shows how the interaction of hydrogen and the stress/strain response may be assessed by diffraction methods. Examples are presented showing that hydrogen alters the load distribution as well as the strain behavior between different lattice planes in high strength steels.
Dynamic-mechanical material analysis as a basis for a general performance exploration complemented by system testing under superimposed climatic and mechanical loading seems to be a promising interdependent test approach addressing the performance behavior of construction sealants under more realistic conditions. With this contribution an attempt is made to adapt dynamic-mechanical material analysis, which has been already successfully validated for different construction types of expansion joint systems in road and bridge engineering, to the field of construction sealants for building façades. Test results from dynamic-mechanical material analysis characterizing the temperature-dependent, deformation-dependent, and frequency-dependent behavior of structural sealant materials are presented and exemplarily discussed for three different sealant products. An attempt is made to address unknown material characteristics in the multi-dimensional loading matrix representing practical use conditions. Furthermore, the applicability of this test approach and its various complex test modes for the exploration of technological performance and especially estimation of fatigue behavior is verified in several examples. Based on this fundamental material exploration, it is planned to complement the dynamic-mechanical assessment methodology by means of system tests on a section of a structural glazing system subjected to a simplified but superimposed loading function. The technical fundamentals and the procedure proposed to develop an adequate system test mode are introduced. The motivation for these investigations is to identify the actual mechanical system behavior under load combinations and for specimens that both closer resemble reality. The objective is to achieve a consistent and interdependent test program complementary to the existing methodology. Finally, the study is meant to initiate further progress toward a performance-related methodology which considers the design, specification, material, and system selection.
The paper will give an overview of new methodology for evaluating the
reliability of NDE systems accurately, reliably and efficiently in accordance with the
specific requirements of industrial application. After a review of the substantive
issues from the previous workshops, the go forward guidance from these
interactions is considered.
At the beginning of the reliability analysis, the actual safety demands have to
be defined in order to fit the investigation to the level of risk when the component
would fail. Next, all the essential influencing parameters need to be documented and
transferred to an appropriate design of experiments (DOE) to determine the
reliability in terms of a qualitative assessment for lower risk or in terms of a
quantitative probability of detection (POD) or ROC (Receiver Operating
Characteristics) curves for higher safety demands. A new paradigm is offered to
consider the POD or reliability of the system as a function of the configuration of
input variables and use it for optimisation rather than for a final judgement. An
advantage for the end user is also to sample all single PODs to an integral 'Volume
POD' of a part.
Among the influencing parameters, the human factor is the most important one.
A systematic psychological approach shall help to find out where the bottlenecks are
but most importantly to provide best possible working conditions for the human
inspectors.
The human factors approach relies on understanding the properties of
human capability and limitations under various conditions and the application of that
knowledge in designing and developing safe systems. Following the principles of
MTO (Man Technology Organization) approach, emphasis should be given to the
way people interact with technical as well as organizational systems.
A model describing human factor influences in relation to the performance shaping
factors and their effect on the manual ultrasonic inspection performance had been
built and a part of it empirically tested. The experimental task involved repeated
inspection of 18 flaws according to the standard procedure under no, middle and
high time pressure. Stress coping strategies, mental workload of the task, stress
reaction and organizational factors have been measured. The results have shown that
time pressure, mental workload and experience influence the quality of the
inspection performance. Organizational factors and their influence on the inspection
results were rated as important by the operators. However, further research is
necessary into the effects of stress.
Hot cracks as stress corrosion cracking initiation sites in laser welded corrosion resistant alloys
(2005)
Although hot cracks at weld surfaces of corrosion resistant alloys (CRAs) might provide access to respective aggressive media and thus, might provide the conditions for a local potential and pH drop, the interaction between hot cracking and corrosion phenomena has not been investigated up to the present. This particularly concerns the initiation of stress corrosion cracking inside such crevices.
As a first approach to clarify the influence of hot cracks on corrosion resistance, considering particularly stress corrosion cracking, hot crack afflicted laser welds of three different CRAs have been subjected to a series of different corrosion tests.
Besides the fact that the Drop Evaporation (DE) Test represents a more realistic procedure than standard immersion tests it turned out that hot cracks can obviously represent an initiation site of stress corrosion cracking in the austenitic stainless steel AISI 309 (German No. 1.4828). The susceptibility of such hot crack afflicted laser welds to stress corrosion cracking (SCC) significantly depends on temperature and chloride concentration of the test environment In comparison, the high nitrogen austenitic stainless steel AISI S 34565 (German No. 1.4565) did not exhibit any stress corrosion cracking associated with hot cracking. This material exhibited pitting corrosion and stress corrosion only in the base material. The Alloy 50 (German No. 2.4850), a Nickel based material, was susceptible to pitting corrosion, but showed no tendency towards stress corrosion cracking at all.
Das Baukastensystem der BAM
(1973)
Grundsätzliche Gesichtspunkte für die Bemessung der Bauten im Bauprogramm II der Bundesanstalt
(1973)
Beitrag zur Bildung der Schnittriefen beim Brennschneiden und zur Bestimmung der Schnittgütewerte
(1973)
Die Fügetechnik in der BAM
(1973)
Anwendung von Radionukliden
(1973)