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Acri A.,AVL List GmbH | Acri A.,Polytechnic of Milan | Offner G.,AVL List GmbH | Nijman E.,Kompetenzzentrum Das Virtuelle Fahrzeug Forschungsgesellschaft mbH ViF | Rejlek J.,Kompetenzzentrum Das Virtuelle Fahrzeug Forschungsgesellschaft mbH ViF
Mechanical Systems and Signal Processing | Year: 2016

Noise legislations and the increasing customer demands determine the Noise Vibration and Harshness (NVH) development of modern commercial vehicles. In order to meet the stringent legislative requirements for the vehicle noise emission, exact knowledge of all vehicle noise sources and their acoustic behavior is required.Transfer path analysis (TPA) is a fairly well established technique for estimating and ranking individual low-frequency noise or vibration contributions via the different transmission paths. Transmission paths from different sources to target points of interest and their contributions can be analyzed by applying TPA. This technique is applied on test measurements, which can only be available on prototypes, at the end of the designing process.In order to overcome the limits of TPA, a numerical transfer path analysis methodology based on the substructuring of a multibody system is proposed in this paper. Being based on numerical simulation, this methodology can be performed starting from the first steps of the designing process. The main target of the proposed methodology is to get information of noise sources contributions of a dynamic system considering the possibility to have multiple forces contemporary acting on the system. The contributions of these forces are investigated with particular focus on distribute or moving forces.In this paper, the mathematical basics of the proposed methodology and its advantages in comparison with TPA will be discussed. Then, a dynamic system is investigated with a combination of two methods. Being based on the dynamic substructuring (DS) of the investigated model, the methodology proposed requires the evaluation of the contact forces at interfaces, which are computed with a flexible multi-body dynamic (FMBD) simulation. Then, the structure-borne noise paths are computed with the wave based method (WBM).As an example application a 4-cylinder engine is investigated and the proposed methodology is applied on the engine block. The aim is to get accurate and clear relationships between excitations and responses of the simulated dynamic system, analyzing the noise and vibrational sources inside a car engine, showing the main advantages of a numerical methodology. © 2016 Elsevier Ltd.

Luber B.,Kompetenzzentrum das Virtuelle Fahrzeug Forschungsgesellschaft MbH ViF | Haigermoser A.,Siemens AG | Grabner G.,Siemens AG
Vehicle System Dynamics | Year: 2010

Testing of the running characteristics of railway vehicles requires well-defined boundary conditions like track geometry quality. Test sections with the same track geometry quality must lead to the same dynamic vehicle response (VR) forces. The state-of-the-art methods do not fulfil this important requirement for a track quality definition. Our proposed method for track geometry assessment considers the vehicle/track interaction. 'Representative' transfer functions are used for the prediction of the vehicle reaction. Therefore, the results show a significant enhancement of the correlation between the track assessment quantities and the VR forces. © 2010 Taylor & Francis.

Pastor J.V.,Polytechnic University of Valencia | Garcia-Oliver J.M.,Polytechnic University of Valencia | Garcia A.,Polytechnic University of Valencia | Mico C.,Polytechnic University of Valencia | Moller S.,Kompetenzzentrum Das Virtuelle Fahrzeug Forschungsgesellschaft mbH ViF
Combustion and Flame | Year: 2016

In the present paper, three different soot-measuring techniques, namely laser extinction method (LEM), 2-color pyrometry (2C) and laser-induced incandescence (LII) have been simultaneously employed to characterize soot distribution inside a diesel flame. Two single-component fuels (n-Decane and n-Hexadecane) and two derived blends (50%Dec/50%Hex and 30%Dec/70%Hex) have been used. Tests have been performed at an optical diesel engine, under different in-cylinder conditions. The study has been complemented with the measurement of ignition delay and Lift-off length. The present work pursues a twofold objective. On the one hand, the effect of fuel properties on soot formation has been analysed, under different engine operating conditions. On the other hand, sensitivity and performance of the three optical techniques has been evaluated, identifying their main advantages and drawbacks in the framework of the current study. LEM has been considered as the reference technique, as the measurement principle can be implemented without important limitations associated to the other two. Results highlight that larger molecules produce more soot than the smaller ones, with both reactivity and soot formation changing with the proportion of the heavier fraction. Despite describing similar trends, LEM and 2C do not provide the same KL values, with the pyrometry reaching some sort of saturation when increasing flame soot. A detailed analysis confirms that 2-Color measurements are strongly biased by soot and temperature distribution inside the flame. Nevertheless, it could still be a good option for low sooting conditions. On the other hand, an attempt to calibrate LII signal by means of LEM measurements has been reported. This approach should make it possible to obtain additional information on the soot spatial distribution. However, inconsistencies have been identified which stem from the inherent limitations of LII technique in highly sooting conditions. © 2015 The Combustion Institute.

Benedikt M.,Kompetenzzentrum Das virtuelle Fahrzeug Forschungsgesellschaft mbH. ViF
At-Automatisierungstechnik | Year: 2014

Regarding non-iterative co-simulation estimation of coupling quantities introduces some kind of distortions which influence the entire simulated behavior of the system. A control-oriented modification of the coupling techniques leads to a nearly complete compensation of the introduced error over the interesting frequency range. An example demonstrates the efficiency of the novel coupling approach for non-iterative co-simulation. © 2014 Oldenbourg Wissenschaftsverlag GmbH.

Schmeja M.,Kompetenzzentrum Das Virtuelle Fahrzeug Forschungsgesellschaft mbH ViF
ZEVrail | Year: 2013

Beside Automotive Applications VIRTUAL VEHICLE, Graz, Austria, is increasingly doing research for the development of methods and tools for the optimization of rail systems. The core approach for the research activities is the holistic view on the system with vehicle, track and the vehicle-track interaction. With its different areas of research like Information- and Processmanagement, Thermodynamics, NVH (Noise, Vibration, Harshness) & Friction, Vehicle Safety & Dynamics und Vehicle E/E (Elektrik/Elektronik) & Software a wide range of topics can be covered, where the cross-linking of the different research areas enables VIRTUAL VEHICLE to exploit synergies and cross domain know-how for the single research projects.

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