A vibro-acoustic model of a diesel engine includes excitations, structural model and model of sound radiation. Valve train and power train excitations are mainly defined using multi-body dynamics. Cylinder pressure is relatively easy to measure but can also be modelled as well as the excitations generated by turbo charger. Structural model is typically FEM-based and utilizes sub-structuring. Several simulation methods are available for the estimation of sound radiation but only a few are usable with large diesel engines. Measurement of valve train and power train excitations is complicated if only a running engine is available. In this paper a test engine which included only the valve train excitations was used. Force measurements from the push rod and from the valve stem were performed and the results were compared with simulation results. The validation of a structural model includes modal analysis of components and various vibration measurements of structures. Structural modes of small and stiff components can be measured up to several kHz but for example the modes of a large engine block are measurable only up to a few hundred Hz. Higher frequencies can be "statistically" validated using FRF-measurements. Measured data can also be used to analyse the modelling strategy of joints, which is one problematic topic of the structural model. Sound radiation is validated using sound intensity method. A reliable estimate of the total Aweighted sound power level of the engine assembly is achievable. More or less valid subarea sound power estimates are typical results of the analysis. Perpendicular mean quadratic velocity of the engine surface can be used to validate the simulation results at high frequencies. One important issue is the validation of the material models and parameters. Especially this concerns temperature and frequency dependent properties of visco-elastic materials which are derived by utilizing the results of Dynamic Mechanical Thermal Analysis (DMTA).
|Title of host publication||18th International congress on sound and vibration 2011, ICSV 18|
|Subtitle of host publication||Proceedings|
|Publisher||International Institute of Acoustics and Vibration IIAV|
|ISBN (Print)||9781618392596, 9788563243010 (CD)|
|Publication status||Published - 2011|
|MoE publication type||B3 Non-refereed article in conference proceedings|
|Event||18th International Congress on Sound & Vibration, ICSV18 - Rio de Janeiro, Brazil|
Duration: 10 Jul 2011 → 14 Jul 2011
|Conference||18th International Congress on Sound & Vibration, ICSV18|
|City||Rio de Janeiro|
|Period||10/07/11 → 14/07/11|
- viscoelastic materials
Lamula, L., Saarinen, K., Rahkola, P., Aura, M., Gao, Z., & Karjalainen, A. (2011). Towards model validation: Virtual model of a large diesel engine. In 18th International congress on sound and vibration 2011, ICSV 18: Proceedings International Institute of Acoustics and Vibration IIAV.