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Next generation Pass-By Noise approaches for new powertrain vehicles

Periodic Reporting for period 2 - PBNv2 (Next generation Pass-By Noise approaches for new powertrain vehicles)

Reporting period: 2019-05-01 to 2021-04-30

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 brought together ESRs and specialists from key players in academia and industry covering different scientific disciplines and industrial stakeholders to optimally tackle the challenges ahead. The ESRs have been trained in innovative PhD topics and have received 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 was 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 were:
- 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 have been developed, outperforming standard foams. A method has been developed for minimising the noise generated by warning-sound sources, required to improve the safety for pedestrians. Machine Learning methods and big data approaches which are capable for long and short term prediction representing the dynamics of traffic by using summary statistics have been developed and demonstrated. A novel substructuring technique that allows for the efficient analysis of the contribution of the car floor panel to the overall vehicle's interior and pass-by noise was developed, leading to faster and more efficient vehicle design. Also a novel method for modal parameter estimation to automate this process has been developed and validated. Finally an estimation framework capable of reconstructing contact forces accounting for the complex interaction between tire and road has been developed. This method can be applied for better and quieter tire design.

WP2 has focused on both simulation and test based transfer path studies. Model Order Reduction techniques for the Boundary Element Method have been proposed, implemented and tested. They significantly extend the state of the art towards the direction of fast but sufficiently accurate acoustic analysis. An inverse Patch Transfer Function method has been developed to be used for blind identification of vibratory fields. Furthermore, the usability of indoor pass-by tests have been improved, by accounting for room effects. Subsequently, a new technique has been developed that allows the tire’s contribution to the total pass-by noise to be estimated from indoor measurements. Component-based transfer path analysis has been progressed substantially, enabling virtual engineering prediction capabilities.

In WP3 technologies related to pass-by noise receiver evaluation and perception have been investigated and developed. The use of low-quality models for jury testing has been investigated and applied. The indoor pass-by noise testing procedure has been extended involving a semi-circular microphone array, together with novel signal processing algorithms. An innovative and simplified tyre model has been developed allowing for tyre noise modelling and optimization. It has also been investigated whether objective evaluation of sound via brainwaves can contribute to the development of exterior warning sounds. promising results. Finally, a methodology to virtually simulate realistic pass-by noise tests has been explored for prediction of pass-by noise levels and sound quality evaluation.

WP 4 focused on the communication, dissemination and exploitation of the PBNv2 results. 2 technical and 2 industrial public workshops have been organized. 4 sessions at conferences have been organised, 38 conference papers have been presented and 9 journal papers were published, while others are still under review. All partners were highly involved in public engagement activities.

WP5 on management ran smoothly. Via GA meetings and SB meetings, organized twice a year, the project was followed-up closely.

WP6 on training also went well. Individual training programs were adjusted to the needs of the ESRs, while all foreseen network wide training courses took place. Specific attention was given to applied training.
The project overall led to progress with respect to the state of the art in many different aspects, as discussed above. The project clearly contributes to safer, cleaner and quieter road traffic:
In particular, the methods of assessing pass-by noise using indoor test facilities will help to enable the development of better products within a short time frame. This pass-by noise measurement work addresses the needs of industry, as raised by industrial members of the consortium.

The numerical methods developed, contribute to better and faster design and characterization of electrified vehicles and their components.

The work carried out contributes to addressing new policies on pass-by noise regulation and on acoustic vehicle alerting systems (AVAS) at a vehicle and component level.

The work carried out can provide the basis for a novel assessment tools for policy makers with regards to traffic noise mitigation measures, such as the ones developed here in accurate road traffic prediction models are necessary for designing suitable traffic strategies and interventions to mitigate urban noise by traffic infrastructure management as well as to provide policy makers with assessment tools for mitigating traffic noise with traffic flow management.