Valve Cover's Numerical Vibro-Acoustic Analysis And Experimetal Correlation

This work describes a numerical vibro-acoustic analysis of a gasoline engine's cylinder head of recent development. The analysis was divided in two main steps: definition and correlation of the numerical model by mean of comparison with tests data, and development of a methodology to identify the potentially critical modes for the NVH performance without knowing the real operational boundaries of the sub-system. The vibrational analysis has focused on the definition of a finite element model for reproducing the behaviour of the component, experimentally obtained by accelerometers placed on the top of the cover. The subsequent acoustic analysis has been executed through a boundary element model. The comparison between numerical results and experimental data was very good. Once the models have been validated and vibration and acoustic transmissibility indexes have been defined, system's critical modes have been identified, disregarding the real forces that arise during engine working conditions; this allows a faster component optimization and, consequently, a reduction of the whole engine system development time, improving it from a NVH point of view. Such methodology had been further validated and developed and is now part of the standard validation plan for new engines. Copyright © 2010 SAE International. This work describes a numerical vibro-acoustic analysis of a gasoline engine's cylinder head of recent development. The analysis was divided in two main steps: definition and correlation of the numerical model by mean of comparison with tests data, and development of a methodology to identify the potentially critical modes for the NVH performance without knowing the real operational boundaries of the sub-system. The vibrational analysis has focused on the definition of a finite element model for reproducing the behaviour of the component, experimentally obtained by accelerometers placed on the top of the cover. The subsequent acoustic analysis has been executed through a boundary element model. The comparison between numerical results and experimental data was very good. Once the models have been validated and vibration and acoustic transmissibility indexes have been defined, system's critical modes have been identified, disregarding the real forces that arise during engine working conditions; this allows a faster component optimization and, consequently, a reduction of the whole engine system development time, improving it from a NVH point of view. Such methodology had been further validated and developed and is now part of the standard validation plan for new engines.