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EU project ODYSSEUS - year 1
(2022)
Vorstellung EU-Projekt ODYSSEUS zum Thema Home-Made-Explosives sowie erste Ergebnisse bzgl. Rezepten, Ausgangsstoffen und Home-Made-Explosives in diesem Zusammenhang.
The volumetric energy density of a gas can be increased by liquefaction, which occurs when the gas is cooled below the saturation point. Liquefied gases of great importance to the energy transition are Liquefied Hydrogen (LH2) and Liquefied Natural Gas (LNG), which can be liquefied at temperatures below 160°C. Systems for storing these gases typically must be overpressure resistant and require thermal super insulations (TSI) to hold cryogenic conditions and minimize boil-off losses from evaporation. TSI with vacuum and MLI or perlites are suitable for many applications involving LNG and LH2. Such systems are typically double-walled structures where the inner wall is in contact with the cryogenic liquefied gas. MLI or perlites are located in the gap between the inner and the outer wall, that is kept under vacuum conditions. This combination of insulations strongly reduces the heat transfer between the environment and the cryogenic liquefied gas. From an economic point of view the systems are well sophisticated. However, knowledge of the behavior of this kind of systems in a typical event such as a fire is limited, but necessary to evaluate the safety of the increasing number of applications.
The objective of the research is to determine how TSI behaves at different fire temperatures during fire exposure and afterwards. Special attention is paid to changes in the heat flux, the material properties and vacuum state over time. For this purpose, thermogravimetric analysis (TGA) studies have been carried out. In addition, a test rig was developed that allows testing of TSI at temperatures up to 1000°C under realistic integration conditions and subsequent analysis of the TSI samples. In the test rig the double-wall with vacuum and MLI or perlites inside is simulated. The fire conditions are simulated on one side of the double-wall by adjustable electrical heating elements. This process allows the implementation of repeatable heat flows of up to 100 kW/m². On the other side of the double-wall, cold or cryogenic conditions are simulated with a heat exchanger through which water or the vapor of liquid nitrogen (approx. -196°C) flows. The heat exchanger is also used to determine the heat flux through the double-wall. Thus, the test rig allows thermal loading and performance analysis of TSI samples at the same time.
Compared to tests with real cryogenic systems, tests with this experimental setup have the advantage that, first, the instrumentation is easier to realize, and a higher repeatability is ensured. Second, the local heat flow can be determined over time, and the sample of a TSI can be taken non-destructively and thus analyzed. Third, the tests are less risky as well as time+ and material intensive, so that more tests and variants can be investigated with the same budget.
Preliminary results obtained considering several types of MLI under vacuum show that all observed typs of MLI can be damaged under strong thermal loading. The damages observed were outgassing, melting, shrinkage, cracking, lump formation, and concomitant local loss of the MLI's function as a radiation shield. However, the study also shows that a damage does not always have an extreme effect on the insulating performance.
Earth buildings and adobe construction have been in use for thousands of years. Loam is locally available, environmentally friendly and has a small CO2 footprint mainly resulting from extraction and transport. Because of these reasons loam is one of the building materials of the future.
Water resistance is an important aspect when using loam as a construction material. If the structural option of building protruding roofs cannot be implemented, the water resistance of clay can be improved by stabilization.
Positive properties of the material should not be diminished by stabilization. For example, the desired regulation of air humidity, which however cannot be fully preserved by cement stabilization.
For an alternative and more appropriate stabilisation, different mixtures with calcined clays with alkali activator were examined. The calcination temperature for clays is usually lower than for cement and starts at 600° C. The calcined clays therefore also have a lower CO2 footprint compared to cement. To keep the mixture environmentally friendly potassium was used as alkali ion. It could be proven that the alkali activated polymer enhances water resistance of the loam mixture. Provided some further optimization the material shows potential to replace cement without compromising on the positive properties of clay.
The low calcination temperature for clays (600° C) and a low CO2 footprint compared to cement make them an interesting material. To find a stabilization method for loam using calcined clays, activation by alkalis was necessary. Therefore (and to keep the mixture environmentally friendly) KOH was used as alkali activator. It could be proven that the alkali activated polymer enhances water resistance of the loam mixture.
Der Vortrag stellt die wesentlichen Inhalte sowie die wichtigsten Änderungen der TRGS 510 "Lagerung von Gefahrstoffen in ortsbeweglichen Behältern" vor.
Die TRGS 510 zeichnet sich durch ein gestuftes Maßnahmenkonzept in Abhängigkeit von der Art und Menge der gelagerten Gefahrstoffe aus. Folgende Maßnahmenstufen werden durch die TRGS 510 beschrieben:
1. Kleinmengen -> Allgemeine Maßnahmen
2. Überschreitung der Kleinmengen -> Lagerung im Lager
3. Überschreitung bestimmter Mengen für spezielle Gefahrstoffe -> Spezielle Maßnahmen
4. Verschiedene Gefahrstoffe und Lagerung im Lager erforderlich -> ggf. Getrenntlagerung und Separatlagerung
According to the NBI database, more than 21,000 in-service U.S. bridges lack sufficient structural documentation necessary for analytical load rating. Among these are a significant proportion of older prestressed concrete bridges. Given the lack of documentation on the reinforcing layout, such structures cannot be load rated analytically and are often subject to engineering judgement as the basis for rating. Otherwise, the typical approach for load rating such bridges is to conduct costly proof load testing and destructive probing together with making conservative assumptions. Therefore, any improvement to current practices will benefit DOTs and taxpayers alike. Accurately reconstructed 3D images of the girders to reflect the internal reinforcement could mitigate the need for costly, if not impractical, destructive testing and proof load testing, and help reduce dependency on conservative assumptions. This study examines a comprehensive NDE approach using ultrasonic tomography and GPR to aid in gathering structural information for load rating purposes. Different types of AASHTO and hollow core girders were tested.
Reaktive Brandschutzsysteme finden im baulichen Brandschutz Anwendung zur Erhöhung des Feuerwiderstands von Stahlkonstruktionen. Neben den Anforderungen an die Feuerwiderstandsdauer können damit auch Ansprüche an die Ästhetik erfüllt werden. Die profilfolgende Applikation und die geringen Trockenschichtdicken der Produkte ermöglichen es, das filigrane Erscheinungsbild von Stahlkonstruktionen aufrechtzuerhalten. Neben der thermischen Schutzwirkung muss auch die Dauerhaftigkeit der Brandschutzbeschichtung sichergestellt werden. Die Bewertungsmethoden, die auf europäischer Ebene durch das EAD 350402-00-1106 zur Verfügung stehen, zielen auf eine Nutzungsdauer von zehn Jahren ab. Prüfverfahren für einen darüber hinausgehenden Zeitraum sind nicht beschrieben. In diesem Beitrag werden experimentelle Untersuchungen zum Einfluss der Bewitterung auf das Expansionsverhalten, zur thermischen Schutzwirkung und zu den während des Aufschäumens im Brandfall stattfindenden Reaktionen vorgestellt. Die Versuche wurden an einem wasserbasierten und einem epoxidharzbasierten reaktiven Brandschutzsystem durchgeführt. Die Ergebnisse wurden im Rahmen des IGF-Forschungsvorhabens 20470 N erzielt.
The Infrastar training school provides lectures and hands-on training to Master and PhD students, early-stage researchers and (young) professionals on all aspects of asset management of civil infrastructures with respect to fatigue of materials. It is organized yearly since 2019 and up to 20 profiles are selected to attend the 3.5-day training.
A team of 7 teachers provides insight in multi-disciplinary and intersectoral basic concepts in three core fields, ranging from the design to the dismantling of the structures (bridges and wind turbines):
1. Monitoring and auscultation,
2. Structural and action models,
3. Reliability, risk and decision analyses.
Each year, a recognized expert is invited to deliver a keynote lecture to raise interest in a specific aspect of one of the fields covered. The presentation is recorded and published on the training school website.
Turning maneuvers of rail vehicles involve demanding situations for the infrastructure because of the steering forces generated and the resultant lateral load transfers. Such forcing situation involves increased tangential forces that consume kinetic energy from the vehicle. While much attention has been paid in the literature to the damage in such infrastructure segments, the energy that is dissipated in these maneuvers, has not been explicitly addressed. In this paper, a specialized scale-down infrastructure is used to characterize the effect of the initial speed of the vehicle and its mass, on the magnitude of both the rail forces developed and the amount of dissipated energy during turning maneuvers. The outputs of the experiments suggest that most of the original kinetic energy is dissipated at the first portion of the turn. Also, that the magnitude of the wheel forces and the amount of dissipated energy, correlate. That is, a greater rail damage would correspond to greater energy dissipation.
The retroreflective corner echo is used, for example, in ultrasonic non-destructive testing of metals to find fatigue cracks in tubes or shafts. If the much weaker crack tip signal is additionally detected, the crack length can also be determined. A corner reflection occurs in cases of surface breaking cracks with predominantly perpendicular orientation to the surface. The intensity of the corner reflection depends on the angle of incidence and on the ultrasonic wave mode used. For the reliable detection of vertical surface breaking cracks in metals, transversal waves are commonly used, which propagate at an angle of 37° to 53° to the inspection surface. As shown in this contribution, the wide spread low frequency ultrasonic arrays with dry point contact sources available for ultrasonic testing of concrete also allow to receive corner echoes. These devices generate transversal waves in concrete structures with a large divergence of the sound field. A series of experiments was carried out with such dry point contact arrays on concrete specimens with artificial test defects and controlled induced cracks of different depths. The ultrasonic time-of-flight signals were recorded, exported and reconstructed utilising the SAFT (Synthetic Aperture Focusing Technique) algorithm. The SAFT reconstruction parameters were adjusted to visualize the corner echo indication. As will be shown, with this targeted processing, the reproducible detection of surface breaking cracks in concrete is possible. The retroreflective corner echo can thus be exploited in civil engineering for non-destructive inspection of concrete.
Turning maneuvers of rail vehicles involve demanding situations for the infrastructure because of the steering forces generated and the resultant lateral load transfers. Such forcing situation involves increased tangential forces that consume kinetic energy from the vehicle. While much attention has been paid in the literature to the damage in such infrastructure segments, the energy that is dissipated in these maneuvers, has not been explicitly addressed. In this paper, a specialized scale-down infrastructure is used to characterize the effect of the initial speed of the vehicle and its mass, on the magnitude of both the rail forces developed and the amount of dissipated energy during turning maneuvers. The outputs of the experiments suggest that most of the original kinetic energy is dissipated at the first portion of the turn. Also, that the magnitude of the wheel forces and the amount of dissipated energy, correlate. That is, a greater rail damage would correspond to greater energy dissipation.
Muon tomography applied to assessment of concrete structures: First experiments and simulations.
(2022)
Non-destructive techniques for reinforced or prestressed concrete inspection such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques. However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened new fields of application. As a first step towards practical application in civil engineering and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. In a second step, we have performed simulations to assess the potential for a set of important testing problems such as grouting defects in tendon ducts. The next steps include the development of mobile detectors and optimizing acquisition and imaging parameters.
This contribution summarizes actual developments and draft fundamental teaching topics in the field of nondestructive testing in civil engineering (NDT-CE). It is based on the first memorandum on teaching and research in the field of NDT-CE at German speaking universities and provides an overview of the academic education and highlights possible focuses, especially in teaching but also takes into account noteworthy developments and topics in research in the field of NDT-CE.
Suggestions are given for the development and advancement of the teaching curricula in regards to a comprehensive and sound professional education of students in civil engineering and adjacent disciplines.
The Infrastar training school provides lectures and hands-on training to Master and PhD students, early-stage researchers and (young) professionals on all aspects of asset management of civil infrastructures with respect to fatigue of materials. It is organized yearly since 2019 and up to 20 profiles are selected to attend the 3.5-day training.
A team of 7 teachers provides insight in multi-disciplinary and intersectoral basic concepts in three core fields, ranging from the design to the dismantling of the structures (bridges and wind turbines):
1. Monitoring and auscultation,
2. Structural and action models,
3. Reliability, risk and decision analyses.
Each year, a recognized expert is invited to deliver a keynote lecture to raise interest in a specific aspect of one of the fields covered. The presentation is recorded and published on the training school website.
Concrete structures are invaluable assets to a society and managing them efficiently and effectively can be supported by information gathered through structural health monitoring (SHM). In this paper, a combined approach based on passive, i.e., acoustic emission (AE), and active, i.e., ultrasonic stress wave (USW) monitoring techniques for application to concrete structures is proposed and evaluated. While AE and USW are based on the same underlying physics, i.e., wave motion in solids, they differ fundamentally with respect to the nature of the source. For the former, external stimuli such as mechanical loads or temperature cause the rapid release of energy from initially unknown locations. As a result, AE events are unique and cannot be repeated. For the latter, a known source at a known location is employed at a specified time. This approach is thus controlled and repeatable. It is
argued that a combination of these two techniques has the potential to provide a more comprehensive picture of ongoing fracture processes, damage progression, as well as slowly occurring aging and degradation mechanisms.
This combined approach does thus promise new opportunities to support condition assessment of concrete structures. After providing an overview and comparison of the two techniques, results, and observations from a full-scale laboratory experiment and an in-service bridge monitoring study are discussed to demonstrate the promise of the proposed combined monitoring approach. Finally, suggestions for further work are presented.
Muon tomography applied to assessment of concrete structures: First experiments and simulations.
(2022)
Non-destructive techniques for reinforced or prestressed concrete inspection such as ultrasound or radar have found regular, successful practical application but sometimes suffer from limited resolution and
accuracy, imaging artefacts or restrictions in detecting certain features. Until the 1980s X-ray transmission was used in case of special demands and showed a much better resolution than other NDT techniques.
However, due to safety concerns and cost issues, this method is almost never used anymore. Muon tomography has received much attention recently. Novel detectors for cosmic muons and tomographic imaging algorithms have opened new fields of application. As a first step towards practical application in civil engineering and as a proof of concept we used an existing system to image the interior of a reference reinforced 600 kg concrete block. Even with a yet not optimized setup for this kind of investigation, the muon imaging results are at least of similar quality compared to ultrasonic and radar imaging, potentially even better. In a second step, we have performed simulations to assess the potential for a set of important testing problems such as grouting defects in tendon ducts. The next steps include the development of mobile detectors and optimizing acquisition and imaging parameters.
To complement the information provided by deterministic seismic imaging at length scales above a certain resolution limit we present the first application of adjoint envelope tomography (AET) to experimental data. AET uses the full envelopes of seismic records including scattered coda waves to obtain information about the distribution of absorption and small-scale heterogeneity which provide complementary information about the investigated medium. Being below the resolution limit this small-scale structure cannot be resolved by conventional tomography but still affects wave propagation by attenuating ballistic waves and generating scattered waves. Using ultrasound data from embedded sensors in a meter-sized concrete specimen we image the distribution of absorption and heterogeneity expressed by the intrinsic quality factor Q−1 and the fluctuation strength ɛ that characterizes the strength of the heterogeneity. The forward problem is solved by modeling the 2-D multiple nonisotropic scattering in an acoustic medium with spatially variable heterogeneity and attenuation using the Monte-Carlo method. Gradients for the model updates are obtained by convolution with the back-propagated envelope misfit using the adjoint formalism in analogy to full waveform inversion.
We use a late coda time window to invert for absorption and an earlier time window to infer the distribution of heterogeneity. The results successfully locate an area of salt oncrete with increased scattering and concentric anomalies of intrinsic attenuation. The resolution test shows that the recovered anomalies constitute reasonable representations of internal structure of the specimen.