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NVH Simulation of ICE-based and HEV Power Units

The need to reduce CO₂ is the major driver in vehicle and powertrain development. Since years important measures to achieve the targets set are downsizing and downspeeding of the internal combustion engine (ICE) while increasing engine power. This leads to higher excitations and rotational irregularities contributing to overall power unit noise. Today’s push towards electrification, from hybrid to full electric powertrains, has become the strongest trend in reducing carbon emissions.

Modern hybrid power units have a higher level of complexity than ICE-based power units, which naturally leads to new challenges for NVH engineers. The addition of the e-motor brings in additional noise sources. and not to be ignored are the different states in which a hybrid drive is operated, partly without the masking noise of the combustion engine.

Consider All IC-Engine and Transmission Noise Sources

Our solution is designed to help you perform all steps of acoustic analysis, from excitation to structural vibrations to noise radiation and airborne noise of the combustion engine and the entire power unit. Next to external forces like combustion pressure in the ICE, or the electromagnetic forces in the e-motor, clearances in the power unit are major noise sources. Such as the cranktrain bearings, piston-liner contacts, contacts in valve trains, timing drives and gear stages of gear drives and transmissions.

Our flexible multi-body dynamics solution AVL EXCITE™ connects Finite Element based bodies via non-linear contact joints. This enables you to investigate all noise phenomena in the ICEs and transmissions.

Efficient Determination of the Cause of Acoustic Issues

Understanding NVH problems and their root cause allows to elaborate the right measures for improvements. To make this process as efficient as possible, we offer a comprehensive set of analysis tools and workflows for NVH root cause analysis. In addition to calculating transfer functions (TF) and operational deflection shapes (ODS), modal analysis of entire assemblies including modal contribution factors (MCF), we offer numerical transfer path analysis (NTPA). The latter is a powerful tool that helps you detect the noise sources that contribute the most to high structural vibration levels. This is specifically helpful for power units that include an ICE with a lot of potential noise sources.

Airborne Noise Prediction

By using the calculated structure-borne noise as input, you can efficiently calculate sound radiation and airborne sound noise results with AVL EXCITE™ Acoustics. These results are subsequently comparable with measured acoustic data and legal noise limits.

In-Duct Acoustics

AVL BOOST™ covers the calculation of in-duct acoustics and intake/exhaust noise, offering linear and non-linear analysis options. This enables you to calculate transmission losses, sound pressure levels in-duct and in free field, and intake/exhaust orifice noise.

Key Benefits

AVL provides a comprehensive solution for NVH analysis of IC-engines and power units that reduces the need for prototyping and avoids expensive NVH troubleshooting:

  • System approach, considering the interaction between ICE, transmission and the e-motor, delivering the most accurate results for vibration and acoustics
  • High computational performance for large simulation models
  • Tools and workflows for NVH root cause analysis - efficient identification of reasons for acoustic problems to derive reliable and effective countermeasures