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Kaufmann R.,Fraunhofer Ernst Machinery Institute | Haring I.,Fraunhofer Ernst Machinery Institute
Safety, Reliability and Risk Analysis: Beyond the Horizon - Proceedings of the European Safety and Reliability Conference, ESREL 2013 | Year: 2014

Geo Information Technology (GIT) and Geo Information Systems (GIS) for visualizing qualitative and quantitative risk analyses are of interest in the areas of large-scale events from disaster scenarios like forest fires and river flooding, to urban scenarios concerning urban security assessment and planning of future cities and quarters as well as military settings like overflight scenarios of moving hazard sources. The paper gives an overview of the range of applications of such 2D, 2.5D GIS and 3D visualizations as well as software tools employed within quantitative risk analyses. The main aim of the paper is to find key criteria for the selection of a suitable visualization for computer-supported risk analyses. We consider different scenario sizes, e.g. from airports to large-scale over flight scenarios with rockets. We distinguish static and dynamic scenarios, e.g. hazard propagation or changes in person distribution. A further criterion for the assessment of the suitability of visualization techniques and tools for quantitative risk analyses is whether GIS and visualization data can be used for risk modeling within one software tool, or more generally, how good the data exchange between the visualization and the modeling can be organized. In summary, we propose for computer-supported quantitative risk analyses applications suitable 3D and GIS visualizations. As basis for the investigation we use a subset of existing, emerging and future risk analysis application tools that are currently developed and take also our software technical framework and development conditions into account. © 2014 Taylor & Francis Group, London.

Siebold U.,Fraunhofer Ernst Machinery Institute | Haring I.,Fraunhofer Ernst Machinery Institute
11th International Probabilistic Safety Assessment and Management Conference and the Annual European Safety and Reliability Conference 2012, PSAM11 ESREL 2012 | Year: 2012

For safety relevant and critical systems a crucial part of the development is a concise and complete safety requirement definition. We show how requirements can be modeled with graphical, semiformal means using the systems modeling language SysML. However, aiming at an unambiguous and formal requirement definition and verification, we do not focus on diagrams that are typically used for requirement definitions, e.g. the SysML requirement, parametric and use case diagrams. We rather use the state machine diagram to define safe and unsafe states as well as sequences of states that are expected within the overall system and within subsystems. We show how generic types of safety requirements are represented using extended versions of state machine diagrams. To this end we model expressions that are similar in semantics to linear temporal logic expressions using the SysML state machine diagrams. In particular, we can distinguish, whether a strict sequence of states is required or some kind of intermediate states are allowed within the sequence, e.g. from an unintended initial unsafe state to a final safe state in case of an active safety function. Finally, we will indicate how this approach can be used in future to verify that overall state machine diagrams of systems or subsystems fulfill these formalized requirements.

Kaufman J.E.,Fraunhofer Ernst Machinery Institute | Haring I.,Fraunhofer Ernst Machinery Institute
Advances in Safety, Reliability and Risk Management - Proceedings of the European Safety and Reliability Conference, ESREL 2011 | Year: 2012

Active protection systems protect vehicles against impact threat, e.g., from high-speed armor-piercing kinetic energy projectiles, shaped charges or improvised devices. Using an on-board computer system and sensors, approaching threats are detected, tracked, classified and then mitigated if found to be a critical threat. In particular, interception of close-in threats in an urban setting, the question arises which safety requirements have to be fulfilled to avoid unintended functioning, possibly resulting in casualties in the vicinity of the vehicle. This paper presents a general approach that applies to any hard-kill active protection system that has to react in a very short time without assuming specific technical system details. The overall functional safety requirements are determined by evaluating individual and collective risk criteria. We discuss alternative derivations of these requirements and their implicit assumptions. We show which requirements have to be fulfilled in typical scenarios. Ranges for critical risk values are also proposed. © 2012 Taylor & Francis Group.

Cunrath R.J.M.,Fraunhofer Ernst Machinery Institute | Wickert M.,Fraunhofer Ernst Machinery Institute
IEEE Transactions on Plasma Science | Year: 2016

Impact and shock wave events represent typical extreme dynamic loads of interest for accessing the response of materials and structures. Here, we focus on an intense electric current pulse as an extreme dynamic load. Experimentally, metallic samples were electromechanically loaded with currents up to 400 kA. For this purpose, a test rig containing a high-voltage pulsed power supply and high-performance switches was built. In this paper, we present an approach for modeling the response of thick metallic wire samples, with diameters on the order of millimeters, to extreme electromechanical loads sufficient for deformation and fragmentation, but not for material disintegration by wire explosion. The essential electrodynamic, thermodynamic, and mechanical aspects are considered, and a way to couple those physical regimes is suggested, which allows the use of numerical simulation based on the finite-element method to determine the material response. Simulations are employed to describe the time-dependent process of the structural and material behavior of thick wires. The focus here is on the structural mechanical behavior including bending or buckling before the onset of the wire explosion. The new approach for a simulation model is able to capture the basic experimental observations. © 2015 IEEE.

Kisters T.,Fraunhofer Ernst Machinery Institute | Kuder J.,Fraunhofer Ernst Machinery Institute | Nau S.,Fraunhofer Ernst Machinery Institute
Shock Waves | Year: 2015

This paper reports on a new gauge for blast impulse determination close to explosive charges. The gauge is based on the autonomous data recorder g-rec developed at the Ernst-Mach-Institute for data acquisition in harsh environments. Combined with an acceleration sensor these data recorders allow for the direct determination of the momentum transferred to an object by a blast wave even in the immediate vicinity of the explosive charge. From this the blast impulse can be determined. Using autonomous electronics distinct advantages are gained compared to classical passive momentum traps. The paper summarizes the properties of the g-rec recorder and describes the setup of the autonomous momentum trap in detail. Numerical simulations are presented which illustrate the gauge performance and its limitations. Tests with 1 kg charges demonstrate the feasibility of the approach. Good agreement was found between simulations and tests. The application range of the gauges is determined by the measurement range of the built-in acceleration sensor and its overall dimensions and weight. The present configuration is designed for distances between (Formula presented.)0.3 and 1 m from charges between several 100 g and several kilograms. Data were successfully collected down to reduced distances of 0.25 m/kg(Formula presented.). Minor changes in gauge dimensions, weight, or measurement range enable the gauges to be deployed at even closer distances. © 2015 Springer-Verlag Berlin Heidelberg

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