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Report

Teaser, summary, work performed and final results

Periodic Reporting for period 1 - VIPER (VIbro-acoustics of PERiodic media)

Teaser

Summary

VIPER is a European Joint Doctorate on Vibroacoustics. VIPER aims at consolidating academic research dealing with VIbroacoustics of PERiodic media. The VIPER projectâ€™ main goal is to develop and to validate tools for the design of global vibroacoustic treatments based on periodic patterns allowing passive control of vibration and acoustic paths in layered concepts. This will be achieved by addressing in-depth structural periodicity stiffness as well as absorption attributes. The proposed concepts will ensure a significant improvement of vibroacoustic performances in a wide frequency range. Dealing with large scale periodic structural-acoustic concepts involves a multi-scale aspect that needs specific numerical tools. The VIPER project main objectives can be summarized as follows:

1 - Addressing most of the theoretical and numerical modelling issues connected to the multi-scale characteristics of the vibroacoustics in periodic media.

2 - Assessment of the topology of periodic structures effects on the vibroacoustic performances.

3 - Focusing on the meso-scale constitutive materials effects, with the improvement of the core material performance for vibroacoustics applications.

4 - Studying the design, feasibility and manufacturing of the periodic media concepts.

Work performed

WP1 was concerned with the development of modelling tools to tackle theoretical or numerical challenges related to multi-scale characteristics of the vibroacoustics in periodic media. Homogenization, model reduction techniques and wave propagation methods for periodic vibroacoustics have been developed. Loading effects and spatially correlated loading of periodic structures are also examined. A full winter school was devoted to this first objective.

The objective of WP2 was to perform topological assessment on the vibroacoustics of periodic media. A special emphasis was made on geometry connectivity and using innovative techniques (e.g. Kirigami, multi-layer core topologies) to design and manufacture periodic honeycomb structures for wave propagation enhancements. A full autumn school is planned to cover this objective.

WP3 successfully addressed the effects of constitutive material classes on the vibroacoustic response of periodic media. These include poro-elastic materials, auxetic materials, viscoelastic add-ons and will pursue with the influence of perforating strategies. Applications are already planned in the low frequency range using combinations and manufacturing of nanostructured materials, inclusions with gradient, poro-elastic and auxetic behaviour. A full spring school is planned for this objective.

WP4 follows the 4th Objective and is dedicated to integration issues and industrial applications. The vibroacoustic performances of the periodic structures has been investigated in terms of robustness (uncertain periodic and quasi-periodic configurations). A full summer school was devoted to this objective.

Final results

Important progress was achieved on the WFEM methodologies: new model-order reduction schemes have been developed for complex periodic waveguides. Combined with homogenization techniques, integration of stochastic effects and complex aerodynamic loadings on axi-symmetric waveguides, these achievements will enable the application of the WFE to large-scaled industrial structures and ensure its further use perform vibroacoustic optimization capabilities for periodic media. It is expected that foreseen industrial case-studies will have positive socio-economic impact as well. These achievements already resulted in several accepted/published papers in international journals and conferences.

VIPER Training Network will provide a highly skilled workforce in a vital area of technologies development within Europe which will have a significant impact on the partners and industry. In that sense, secondments, workshops and multi-disciplinary courses contributed to the skill development of the ESRs. Organization of several schools inviting outstanding lecturers from the academic side and participants from the industry had highly positive impact on their training. The Fellows were trained in state-of-the-art CAE methodologies and software. This includes a good understanding of currently used predictive modelling methodologies and optimization.