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Bad Essen, Germany

Berger A.,ESI Gmbh | Berger A.,Queen Mary, University of London | Pyttel T.,Mittelhessen University of Applied Sciences | Duddeck F.,Queen Mary, University of London | Duddeck F.,TU Munich
International Journal of Crashworthiness

Fibre reinforced plastics are widely used for energy absorbing parts. Due to their superior strength to density ratio they provide a high performance and are ideal for lightweight design for crashworthiness. For this, it is essential that the mechanical behaviour of fibre reinforced composites be predicted correctly by simulation. However, due to the complex inner structure, this is still a challenging task, in particular in case of highly nonlinear crash loading. In order to provide an alternative in this paper a virtual manufacturing simulation chain is proposed to gather detailed geometrical information about the roving structure of a filament wound tube on meso-scale. In addition effective material properties, based on calibrated models of the individual constituents, for the filament-matrix interaction are derived by micro-scale calculations. Both, combined with a USER MATERIAL model for the roving structure finally provide a complete finite element model which is used for the crash simulation of the filament wound tube. By comparing the numerical results to experimental data, the potential of the approach is shown and occurring differences are discussed as well as possible subsequent investigations are proposed. © 2014 Taylor and Francis. Source

Pyttel T.,Justus Liebig University | Liebertz H.,Volkswagen AG | Cai J.,ESI Gmbh
International Journal of Impact Engineering

A failure criterion for laminated glass in case of impact is presented. The main idea of this criterion is that a critical energy threshold must be reached over a finite region before failure can occur. Afterwards crack initiation and growth is based on a local Rankine (maximum stress) criterion. The criterion was implemented in an explicit finite element solver. Different strategies for modeling laminated glass are also discussed. To calibrate the criterion and evaluate its accuracy, a wide range of experiments with plane and curved specimens of laminated glass were done. For all experiments finite element simulations were performed. The comparison between measured and simulated results shows that the criterion works very well. © 2010 Elsevier Ltd. All rights reserved. Source

Hufenbach W.A.,TU Dresden | Blanchet D.,ESI Gmbh | Gude M.,TU Dresden | Dannemann M.,TU Dresden | Kolbe F.,TU Dresden
Proceedings of ISMA 2010 - International Conference on Noise and Vibration Engineering, including USD 2010

Lightweight composite structures for high-technology applications have to fulfill high demands on low constructive weight combined with an adequate stiffness. In general, the low structural weight leads to high vibration amplitudes due to low forces of inertia and causes an undesired sound radiation. This effect can be compensated by exploiting the high vibro-acoustic potential of fibre-reinforced composites. For this purpose, an integrated calculation algorithm for the transmission loss, considering the eigenfrequencies (modal analysis) and the estimation of modal damping values, is presented. Therefore, an ANSYS loop is combined with an especially developed VA One batch file. The developed model enables the calculation engineer to study the influence e.g. of the fibre orientation on the radiated sound power of a fibre-reinforced structure with a complex geometry. Source

Blanchet D.,ESI Gmbh | Blanchet D.,ESI Group | Golota A.,ESI Gmbh | Zerbib N.,ESI Group | Mebarek L.,ESI Group
SAE Technical Papers

Recent developments in the prediction of the contribution of wind noise to the interior SPL have opened a realm of new possibilities in terms of i) how the convective and acoustic sources terms can be identified, ii) how the interaction between the source terms and the side glass can be described and finally iii) how the transfer path from the sources to the interior of the vehicle can be modelled. This paper discusses in detail these three aspects of wind noise simulation and recommends appropriate methods to deliver required results at the right time based on i) simulation and experimental data availability, ii) design stage and iii) time available to deliver these results. Several simulation methods are used to represent the physical phenomena involved such as CFD, FEM, BEM, FE/SEA Coupled and SEA. Furthermore, a 1D and 2D wavenumber transformation is used to extract key parameters such as the convective and the acoustic component of the turbulent flow from CFD and/or experimental data whenever available. This paper focuses on process implementation and presents simulation results from coarse to detailed simulation models and compares these with experimental data. Copyright © 2014 SAE International. Source

Vogel M.,University of Manchester | Khan M.,University of Manchester | Ibarra-Medina J.,University of Manchester | Pinkerton A.J.,University of Manchester | And 2 more authors.
ICALEO 2012 - 31st International Congress on Applications of Lasers and Electro-Optics

Laser Direct Metal Deposition (LDMD) has proved a versatile technique, but a recognized problem that has still not been overcome is the transient and residual stresses that are generated during the process. These can lead to cracking or to a reduction in final properties and expected lifetime of any product produced by the method. In order to understand and work towards ways to reduce the stresses, this paper presents a versatile model to predict them. The model couples computational fluid dynamics methods with finite elements methods so that all necessary physical effects including the gas-powder flow, the laser-powder interaction and melt pool dynamics are covered. Inputs to the model are the known LDMD process parameters such as powder mass feed rate and laser power. The model is explained and verified against 316L stainless steel parts built with a coaxial laser deposition system. Modeled and measured residual stresses distributions agree well. Source

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