B10
Impact Shock & Crash 1

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08:35
conference time (CEST, Berlin)
Simulating Windborne Debris Actions on Laminated Glass Facades
27/10/2021 08:35 conference time (CEST, Berlin)
Room: B
J. Smith, D. Aggromito, J. Farley, J. Klimenko, L. Pascoe (Arup, AUS)
J. Smith, D. Aggromito, J. Farley, J. Klimenko, L. Pascoe (Arup, AUS)
Climate change research predicts that the occurrence of high wind speed (Category 4 or higher) storms could increase by up to 59% globally by late this century. Such wind speeds, when combined with windborne debris can result in dangerous overloads of building façades, increasing the risk of injury to occupants and the public in the surrounding area. Current industry practice for evaluating the impact of windborne debris is physical testing, which can be costly and time intensive for system development while also being unable to capture the combined effects of wind action and debris impact. Simulation is capable of quickly iterating through multiple design variables while also reducing variation found in physical tests. Combining the reduced development time and cost, with the ability of the simulation to capture both wind and debris actions on the façade makes simulation an attractive option for the design process. LS-Dyna has been used widely to simulate windshield impacts in the automotive sector. The authors have previously published a paper characterising a laminated glass pane to simulate the delamination and fragmentation response of glass in a blast event. In this study, a computational model in LS-Dyna was developed and correlated with physical testing of laminated safety glass panes subjected to blast loads. In order to generate an accurate model, validation of the component parts including PVB, adhesion and glass that make up the laminated safety glass was completed. This model was compared to tested samples undergoing windborne debris impact as per AS1170.2:2011 “Part 2: Wind Actions” which includes a provision for test requirements by building type and geographical location. By altering mesh density and patterns to examine crack distribution, a model has been developed to simulate impact from windborne debris which demonstrated good correlation. This highlights the applicability of simulation for impact testing and provides examples of potential applications in façade design.
Simulation,Testing,LS-Dyna,Validation,Glass,Facade,Impact
08:55
conference time (CEST, Berlin)
Simulation Methodology Investigations for the Assessment of Civil Aircraft Shieldings with Diverse Materials
27/10/2021 08:55 conference time (CEST, Berlin)
Room: B
Y. Toso (DLR - Deutsches Zentrum für Luft- und Raumfahrt, DEU)
Y. Toso (DLR - Deutsches Zentrum für Luft- und Raumfahrt, DEU)
Greening the air traffic is a very challenging task for the engineers. The economic requirements, the overall energy consumption throughout the whole life cycle and the safety standard should at least stay constant or be improved. Different new technologies are therefore developed within the European Clean Sky II Program. The development of simulation methodologies for the assessment of the impact behavior of new materials against potential threads is one of them. In a first step, two reference materials (the aluminum Al2024T3 and the UD T700/M21) as well as two promising shielding materials (the tri-axially braided AS4c carbon fiber reinforced M36 epoxy and the tri-axially braided Zylon fiber reinforced CYCOM 890 epoxy) were selected as materials for the investigations. Material characterization test results were employed to determine the parameters of appropriate material cards within the commercial simulation software Abaqus® Explicit. In a third step, high velocity impact test campaigns were performed for each material to assess their impact performances. A steel ball, a long composite projectile, and a generic debris were chosen to create a test matrix. The simulation methodology was validated for different target materials with selected high velocity impact test results. The influence of the mesh size on the quality of the simulation results as well as on the simulation time was investigated. Considering those results, suitable meshes and material card parameters were chosen within the validated simulation results to assess the impact behavior for two generic high velocity impact cases: a very small steel debris (from an auxiliary power unit) impacting a flat target and a blade of an open rotor impacting a fuselage skin component. The investigations show so far that a large number of effects take place in impact events with the considered threads and that simulations are unavoidable in the selection of appropriate shielding solutions.
high velocity impact, tri-axially braided composite, APU debris, blade impact
09:15
conference time (CEST, Berlin)
Towards a Framework for Automatic Local Event Detection for Car Crash Simulations
27/10/2021 09:15 conference time (CEST, Berlin)
Room: B
D. Steffes-lai, M. Pathare (Fraunhofer SCAI, DEU); J.Garcke, (Fraunhofer SCAI and Universität Bonn, DEU)
D. Steffes-lai, M. Pathare (Fraunhofer SCAI, DEU); J.Garcke, (Fraunhofer SCAI and Universität Bonn, DEU)
In the virtual product development of a car, numerous design changes are applied and analysed until the final model satisfies given design criteria. We focus on crashworthiness requirements, where this procedure usually results in large development trees with many design changes and corresponding simulation results. Following a path in the obtained development tree, the differences from one simulation to the next consist of one or several design variations, which result in numerous changes in the crash behaviour. These differences are mainly determined by local changes in a subset of the car parts. During the development process each of the design variations has to be analyzed and its influences on the crash results have to be compared and evaluated. To simplify and structure this process, we developed a framework to easily analyze the impact of design variations, including a structured data representation. First, we analyse and store the design variations from one model to the next. Second, in order to detect events, such as anomalies or unusual variations in mesh quantities such as deformations or plastic strain, we analyse and store the changes between the two obtained simulation results. Moreover, we developed a tool to automatically highlight the most relevant parts together with the local areas of high deviations between the two simulation runs. The comparison can be based on arbitrary node- and element data functions, e.g. displacements, plastic strains, or thicknesses. The presented framework is an important step towards automatic design and event detection in an overall simulation data analysis workflow. It allows to systematically analyze a design development tree to detect interesting deviations in the crash behaviour caused by design changes and to store these observations in a structured data representation for further analysis by for example artificial intelligence approaches. We demonstrate the framework on a frontal crash example.
Anomaly detection,design variations, crash simulation, simulation data management
09:35
conference time (CEST, Berlin)
Assessment of the robustness of vehicle restraint systems crash tests by numerical simulation and consequences on the regulation
27/10/2021 09:35 conference time (CEST, Berlin)
Room: B
C. Goubel, V. Lapoujade, C. Michel, J.Pourcelot (DynaS+, FRA)
C. Goubel, V. Lapoujade, C. Michel, J.Pourcelot (DynaS+, FRA)
Road safety structures are CE-marked products. The declared performances are obtained during crash tests defined within EN1317. These crash tests are performed using second-hand vehicles which only need to fulfil very few requirements (mainly global dimensions and total mass). As a consequence, the vehicles used in different test laboratories differ from one another. Numerical simulation has been widely used for several decades to assist in the design of new road safety devices. The above-mentioned variability of the vehicles affects the reliability of the simulations, leading to discrepancies between models and real tests results. Indeed, vehicle restraint systems performances may be different depending on the vehicle used for the crash test. In a first part, this paper presents correlations between tests and numerical simulations using LS-DYNA software, on various vehicle restraint systems made of different materials (steel, steel-wood, concrete…) and of various restraint levels, in order to show the capability of the models to represent the experiments. In a second part, the vehicles models are modified, while still respecting the EN1317 requirements, and the corresponding impacts on the products performances are evaluated. Finally, some simulations with impactor models are presented as a proposal to reduce the variability of the crash tests and then increase the reliability of the CE marking.
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