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Next generation Pass-By Noise approaches for new powertrain vehicles

Periodic Reporting for period 1 - PBNv2 (Next generation Pass-By Noise approaches for new powertrain vehicles)

Reporting period: 2017-05-01 to 2019-04-30

With transportation noise being the second most deadly environmental pollutant in Europe, engineering for future mobility must be inspired by ecology, economy and health to enable green and silent vehicles. Legislations define maximum noise emission limits that have to be complied with during standardized pass-by noise test procedures. Given novel, often electrified, vehicle powertrain concepts, new pass-by noise evaluation approaches are required.

The PBNv2 project brings together ESRs and experienced specialists from key players in academia and industry covering different scientific disciplines and industrial stakeholders to optimally tackle the challenges ahead. The ESRs are trained in innovative PhD topics as well as receiving specific theoretical and practical education in the field of pass-by noise engineering, focusing on aspects of the ‘source’, the ‘transfer path’ and the ‘receiver’.

PBNv2 is formed by 10 beneficiaries as well as 9 partner organisations established in European automotive R&D, to assist in the dissemination and public engagement or PBNv2 results, and in providing dedicated training to enhance the entrepreneurial mind set of the ESRs.
The general objectives of the project are:
- To bundle knowledge and research activities in the inter/multidisciplinary field of pass-by noise evaluation in order to achieve a decisive step forward in the development process of safe, quiet vehicles.
- To stimulate interaction between industrial needs and academic research capacity in a joint training programme for ESRs.
- To motivate young researchers through research combined with training measures not available at common education sites and universities.
- To provide a balanced training program, considering the education stage of the researchers and their needs to efficiently progress in their scientific work, including transferrable skills.
- To promote transfer of knowledge amongst the consortium participants and to disseminate the research output to the European community and publically engage it to the general population.
- To facilitate the mobility of researchers according to their needs.
- To specifically address woman researchers in order to make use of their potential and talent pool.
In WP 1 work has been performed in the field of noise sources in the context of vehicle pass-by to develop novel approaches for noise and vibration mitigation, warning sound devices and noise characterisation. Enhanced acoustic trim materials for engine bay abatement are under study. A predictive, numerically efficient approach to calculate the dynamic excitation forces in coarse road-tire contact was developed and was validated with experimental results. A prototype of a directional warning sound system was built following a simulation-based study, and evaluated. Vibrational load characterization and mitigation of an integrated e-drive component was performed and reduced sub-component models were used to estimate the dynamics of the assembled structure.

WP2 has focused on both simulation and test based transfer path studies. Model Order Reduction techniques for the Boundary Element Method have been proposed. Also work has been performed on hybrid approaches to Passby-Noise Engineering, which combines the benefits of simulation and experimental testing. Methods are being developed to separate radiated sound fields into the constituent components using the inverse Patch Transfer Function method. Inverse methods have also been applied to the quantification of tire noise source contributions within an indoor pass-by noise test facility and a new l-1 norm optimization procedure was proposed.

In WP3 technologies related to pass-by noise receiver evaluation and perception are investigated and developed. Related to the noise perception and detectability several experimental tests and modelling activities have been conducted, the final goal will be to understand which model parameter is more relevant for the sound detectability, with special attention to the tire noise radiation at low speed. Moreover, since the noise perception is rather subjective, a researcher is focusing on objectifying the noise perception by analysing brain signals, and preliminary results have shown very promising results. Finally, a methodology to virtually simulate realistic pass-by noise tests is explored for prediction of pass-by noise levels and sound quality evaluation.

Concerning WP 4 on communication, dissemination and exploitation, everything is going according to plan: the website (both the public and the intranet one) are up to date. The first public technical course has been organized. First conference papers have been presented and first journal papers have been submitted. All partners are highly involved in public engagement activities.

Also for WP5 on management, everything is on track: The consortium agreement was signed by all partners, GA meetings and SB meetings are organized twice a year, the DMP is continuously updated.
Finally, WP6 is related to definition and controlling of individual training activities. From the beginning of the project, an Excel file storing all the information about training activities followed by each ESR in or out the framework of the project has been created. In the same document, all the conference attendances of ESRs are listed. This document is regularly updated. Also the CDPs have been collected for this 1st period. Finally all scheduled training activities have been organized.
The concepts for source characterisation will be validated in industrial applications. Broadband sound absorption solutions with compact design are aimed for to reduce weight and material usage resulting in a more environmental friendly solution.
The algorithm to adapt the content of a warning sound depends on the sonic environment. This algorithm is to be evaluated through a series of listening tests. The final aim is to incorporate different approaches in a single system. The main drive behind this work is to ensure pedestrian safety while avoiding an increase in noise pollution, thus helping establish the viability of EVs.

On the transfer path, the MOR method developed for BEM will enable large-scale acoustic simulations, including those required for Pass-By Noise prediction. The further development of the proposed method within the project will lead to impacts for the design of acoustic systems, reducing the need for repeated costly experimental testing. The development of the iPTF method will enable greater practical understanding of the noise source contributors in complex practical systems, and will thus assist in the development of improved low-noise design methods, thus potentially reducing the impacts of environmental noise radiation. Finally, the development of the proposed microphone array based indoor passby-noise test procedures will enable automotive manufacturers to more reliably utilise indoor tests to develop and validate their vehicles, thus reducing development time and costs.

In the context of reducing vehicles exterior noise, complying with the maximum noise emissions regulations, vehicles are becoming an hazard for pedestrians, especially for visually impaired and elderly people. The research activities related to the receiver are expected to bring the pass-by noise testing to the next level in which the humans psychoacoustic factors will be taken into account for an improved detection and localization of vehicle sounds.