Riassunto analitico
Pass-by noise testing is performed to assess the compliance of vehicle sound emissions to the limits set by Regulation (EU) 540/2014 of vehicles of category M1 for type approval and conformity of production. The testing procedure follows the provisions of the UNECE Regulation No. 51.03, in which are defined test conditions, equipment and procedures set to reproduce the sound levels generated by vehicles during normal driving in urban traffic. Annex 7 of the same regulations provides with the Additional Sound Emission Provisions (ASEP) a broader operating condition range and target cycle-beating. ASEP tests are limited to vehicles equipped with internal combustion engines and are not mandatory for type approval as they must only be certified through a statement of compliance by the OEM, remaining that the type approval authority can still ask the manufacturer to witness a test at any time. ASEP inclusion in the type approval procedure is considered to increase its credibility, but it is deemed excessively complex and time-consuming by the manufacturers.
In Amendment 07 to the R51.03 is introduced a new Annex 9, which defines the Real Driving Sound Emission Provisions (RDASEP). This set of procedures is intended to be included in the mandatory type approval workflow and aims at improving the off-cycle testing capabilities, widening the testing range of operating conditions and considering a larger array of vehicle technologies.
RDASEP propose a new sound expectation model to determine the limit sound emission values and a revised testing procedure, characterized by the non-predictability of the operating points to be tested during type approval, since they are decided on the spot by the technical authority present at the test.
The aim of this thesis is to investigate the influence of RDASEP on pass-by testing and to develop an internal data analysis tool for the evaluation of the acoustic performance of the vehicles in a deeper manner compared to the official UNECE worksheet. In this way, a prediction of the relevant type approval points and the compliance margin can be performed and utilized as first reference for acoustic design and vehicle homologation, obtaining an early overview of the company vehicle fleet behavior in anticipation with the starting of the official RDASEP testing scheduled on the 1st of July 2023.
Firstly, a detailed study of the regulation is carried out and a draft calculation sheet is derived from an old reporting tool used for Annex 3 and ASEP evaluation. Then, a preliminary wide-scope testing activity is performed on a single vehicle, to obtain a set of RDASEP-specific data, which are used to develop dedicated code for data acquisition, management and analysis. Relevant plots and correlations are formulated and used for the optimization of the testing procedure, which is subsequently employed for further testing of vehicles of different types and powertrain configurations. Supplementary considerations are taken regarding the main source contributions to the traffic noise emission and their implementation in the proposed sound expectation model.
Additionally, remarks regarding suitability of the model for the intended function, ambiguities and eventual criticalities are drawn and discussed within a RDASEP working group and brought up for discussion with the relevant authorities.
Eventually, all the conclusions drawn from the study are produced as results to the Porsche traffic noise department, along with the measurement data gathered during the pre-testing campaign, a purposefully optimized testing procedure and a comprehensive tool for data analysis which serves both as a ready-to-use reporting software for the upcoming official testing campaign and as development tool for further pass-by noise evaluations.
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