Elastomer Solution for Naval Acoustics and Sealing Design – SEALENCE

The project is an industrial research program. It brings together three engineering stakeholders from the Pays de la Loire region to study the mechanical behaviour of elastomers as applied to marine applications:
• Centrale Nantes, a top 5% French engineering “Grande École’’,
• Naval Group, an international defence company,
• Cetim, the French technical centre for mechanical industries.
This chair proposes an ambitious collaborative research programme on a new subject, build on the already well-established relationships between the three partners, in terms of research (co-supervised theses), industrial services and education (hosting of Centrale Nantes’ trainee engineers).

Two applications of the industrial partners, the response of elastomers filled with thermoplastic microspheres for acoustic discretion in submarines and the dimensioning of elastomer seals under high-pressure loads, have led to the emergence of a scientific issue that remains an open problem today: the characterization and prediction of the compressible response of elastomers under loading conditions with a strong hydrostatic component. Centrale Nantes' international reputation in mechanics of elastomers, and in particular that of the project leader Prof. Erwan Verron, will enable to tackle experimental, theoretical and numerical aspects of the question.

The scientific challenges are classical in the field of mechanics of materials.
• From the experimental point of view, the partners already have complementary equipment for studying the hydrostatic response of soft organic materials. The challenge is to create an ``experimental continuum’’ between these and to couple them with more standard experimental devices (tension or shear), so as to be able to characterize the complete hydrostatic/deviatoric response of elastomers.
• From the theoretical point of view, we will challenge the spherical/deviatoric multiplicative split almost universally adopted today; this will lead to the derivation of new hyperelastic constitutive equations to be coupled with viscoelastic creep/relaxation formulations.
• Finally, from the numerical point of view, the results will be integrated into industrial partners' finite element tools and coupled with methods for identifying material parameters dedicated to the models developed.

The project has a simple structure. In addition to a management work package, it includes two technological work packages, each dedicated to one of the industrial issues, and a more fundamental work package for the formalization of both constitutive models and numerical methods. In addition to the permanent staff (3 academics from Centrale Nantes, 1 research engineer from Naval Group and 1 from Cetim), the work will require the recruitment of a post-doctoral fellow (2 years), two PhD students, and a design engineer (4 years) for the ambitious experimental program.

Finally, the SEALENCE project will consolidate and, above all, perpetuate an already existing regional expertise between the involved partners. In addition, the complementary nature of our experimental resources will constitute a unique tool ensuring the future consortium's international influence on the subject of elastomer compressibility.