Assessment of Noise Source Integration Effects within a Virtual Certification Process
Invited paper
Vibratec
Wednesday 3 june, 2015, 10:20 - 10:40
0.1 London (90)
Abstract:
The Acoutrain FP7 European research project has come to an end in 2014. Its objective was to show how the classical TSI-Noise homologation process or parts of it can be replaced by virtual testing.
This paper deals mainly with noise from traction and auxiliary systems. These sources are responsible for the noise at standstill and can also contribute to pass-by noise.
Installation effects are effects such as screening and absorption which modify the transfer path between source and receiver in comparison with free field propagation. In Acoutrain, a prediction tool is developed to assess standstill and pass-by levels. It accounts for the influence of a partly reflecting ground but does not include the prediction of integration effects close to the source. These must therefore be accounted for in the source description. Integration effects can be measured on similar existing rolling stock or predicted. It is displayed how analytical models can be used to calculate the insertion loss of screens for sources that can be represented by point sources. Ray tracing and energy BEM models are used to determine the high frequency installation effect of a source in the bogie and a practical procedure for in-situ testing of installation effects is suggested.
It is concluded that the results to date are promising but more work is needed to validate the proposed process and methods for real vehicle installations in terms of modelling accuracy and usability in a virtual testing framework for TSI certification purposes.