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Im Rahmen der von der BAM und anderen Partnern ins Leben gerufenen Initiative „Digitale Qualitätsinfrastruktur“ liegt der Fokus u.a. auf der Entwicklung von neuen Zertifizierungsworkflows. Dabei ist eine besondere Bedeutung dem Zusammenführen von Operational Technology (OT) und Informationstechnik (IT) beizumessen. Zur Datenintegration aus der Sensor-Feldebene einer Versuchs-wasserstofftankstelle wurde eine solche Infrastruktur zunächst in einer Laborumgebung aufgebaut.
Protection against terroristic or accidental scenarios in industrial settings requires suitable designs of structures to resist blast loads. Field testing as well as finite element simulations are among the techniques available to engineers in the understanding of the structural behavior against blast loading.
As blast testing of complex scenarios can be very resource intensive, tests are generally performed for simplified scenarios. Numerical tools can be used to model these scenarios to get better insight into blast loading, structural response, and the resulting damage to the structure. During the next steps, the simplified scenario is successively modified in numerical simulations to incorporate complexities that cannot be covered in blast testing experiments. One of the conditions for this approach to work is that the original simplified numerical simulation is valid. The scopes and challenges encountered in such a validation are the focus of this presentation/article.
A relatively ‘simple’ field test of a horizontal reinforced concrete (RC) slab subjected to blast loading is taken as an example for validation of the performance of numerical tools. The blast test incorporated various measurement techniques to quantify the blast load as well as the behavior of the RC slab. Blast load was measured using flush mounted piezoelectric pressure gauges, whereas acceleration sensors and fiber-optic sensor cables were used to characterize the dynamic behavior of the slab under blast loading. Additionally, damage characteristics were ascertained also using fiber optic sensing. The application of such measurement techniques, along with different numerical software available for the analysis of the scenario in question, demonstrate the scope of our contribution.
When it comes to the challenges, it begins with proper instrumentation of the test specimen followed by the data processing. For numerical modelling, geometric conditions with appropriate boundary constraints, physical conditions such as the configuration of the rebars, as well as material parameters add to this challenge. The issues of choosing appropriate material models and comparison of results with multiple software tools will be discussed. This discussion forms the basis for a coherent approach to technical-safety assessment of blast effects on structures in its broader sense.
Das Poster beleuchtet das EU-Projekt ODYSSEUS im Rahmen des Förderprogramms Horizon 2020. Das Konsortium besteht aus 18 Partnern aus 13 Ländern aus Forschung, Entwicklung, Industrie sowie Behörden und Organisationen mit Sicherheitsaufgaben. Das Forschungsprojekt zielt darauf ab, das Wissen über Ausgangsstoffe von Sprengstoffen und selbst hergestellten Sprengstoffe, einschließlich bisher nicht untersuchter Vorläufersubstanzen, zu erweitern und wirksame und effiziente Prognose-, Aufdeckungs- und kriminaltechnische Instrumente zu entwickeln, um die Fähigkeiten der nationalen Sicherheitsbehörden bei der Verhütung, Bekämpfung und Untersuchung terroristischer Vorfälle mit HMEs zu verbessern.
Current capabilities for full-scale field testing are highly resource intensive. Reliable small-scale experiments are an effective alternative. Characterization of the dynamic response and damage of RC elements to scaled blast loads was investigated in scaled-down field experiments. Spatially resolved information on the dynamic structural response using distributed fiber optic acoustic sensing (DAS) and acceleration as well as blast loading by piezoelectric pressure sensors.
For structural health monitoring systems or non-destructive testing, it is crucial to study the interactions of ultrasonic-guided waves with inhomogeneities or damage in structural components. Simulation of these interactions poses a challenge.
After the wave-damage interaction, the numerical model must reproduce features like mode conversion or wave scattering. Mathematically, damages are discontinuities in a computational domain, and each wave interacts differently because of the geometrical features. We propose a quadtree-based meshing in the current contribution to capture these geometrical characteristics.
This kind of discretisation approach requires special techniques to couple cells of different sizes since, after a quadtree decomposition, the problem of so-called hanging nodes may arise. Transition elements based on high-order transfinite shape functions are used to solve this issue. The advantage is that these elements allow the correct coupling of the cells while retaining a high-order interpolation. Moreover, the reuse of the dynamic stiffness matrices can be exploited based on the similarity of the cells. This procedure makes the approach very efficient.
Examples show the scattering characteristics of different guided wave modes after interacting with inhomogeneities and discontinuities in a plate.
In the field of guided waves for non-destructive testing, the interaction of these waves with damages or other discontinuities in a structure is critical. When a guided wave mode travels and hits a defect, it scatters in all directions, converting to other modes and reflecting the existing one. These interactions are captured in scattered far field complex amplitudes. The amplitudes are stored in scattering matrices, which characterise the elastodynamic behaviour of a defect completely. Scattering matrices are also useful to simulate backpropagation from a defect using ray-tracing methods.
Simulating these interactions is challenging, and analytical solutions only exist for simple geometries. Still, using general tools like the finite element method results in large, usually costly models. Recently, researchers proposed a method based on a numerical implementation of the Kirchhoff–Helmholtz integral that allows the computation of the scattering matrices using a model containing only the damaged region. However, classical methods to resolve the far field and low-order elements were used, leading to large models yet more efficient than using other techniques.
We propose using the SBFEM as an alternative to enhance the computation of the far field scattering. The damaged region is discretised using high-order polyhedral elements, while the far field is constructed using a modified version of the SBFEM. Examples compared to the literature demonstrate the validity of the approach.
Die fortschreitende digitale Transformation der Wirtschaft und die zunehmende Komplexität vernetzter Produkte und Anwendungen rücken die Digitalisierung in den Fokus von Konformitätsbewertungsstellen (KBS). Die Nachfrage nach Konformitätsbewertungsdienstleistungen im Einklang mit Innovationen, neuen Technologien und Prozessen steigt. Dies stellt Prüf- und Kalibrierlaboratorien, Inspektions- und Zertifizierungsstellen und andere KBS vor neue Herausforderungen. Der Fortschritt digitaler Technologien und Anwendungen eröffnet diesen Organisationen gleichzeitig neue Chancen. Diese Studie ist die erste, die das Thema der "Digitalisierung in der Konformitätsbewertung" umfassend erforscht. Sie stützt sich auf Daten aus einer Online-Umfrage unter KBS weltweit (14 Länder und Westafrika als Region mit sieben Ländern).
The structural integrity of outer reinforced concrete (RC) containments of nuclear power plants provides an essential shield against external hazards. If this containment is damaged by an impact event, such as an aircraft crash, the question arises to which degree the reinforced concrete containment still has its protective capability. This concerns both purely structural protection and protection against liquids penetrating the interior of the containment. Due to the dimensions of the containment structures, it is difficult to perform real scale impact experiments, so in the past decades plate geometries at medium scale have been used for investigations. Detailed investigations on the structural behaviour of RC members or RC plates subjected to impact loading have already been presented in Just et al., Hering, Hering et al., Bracklow et al., Hille et al. and Nerger et al.
The following investigations deal with the single and multiple impact event (first hard impact and/or subsequent soft impact) on a RC specimen, which provides the basis for further investigations. A description of the test setup and the test procedure as well as a presentation of the test results from the impact tests are provided.
Furthermore, the experimental program is presented, which the damaged RC specimens are to undergo to deal with the question of how much the impact-damaged RC structure has become permeable to liquid media, such as water and kerosene, depending on the intensity of the impact. The aim of these following investigations is to develop a test setup that can be applied to investigate the liquid penetration behaviour (LPB) of small, medium, and large-scale RC members.
In addition to the liquid penetration experiments, the damaged specimens are to be examined by planar tomography to obtain the damage inside the specimen. The combination of damaging event, fluid penetration behaviour and tomography should enable a comprehensive understanding of the damage to the RC specimen.