PhD Defence of Benoît Wittmann

13 December 2020

Benoît Wittmann defends his PhD in Numerical Mechanics and Materials on Nov. 17th, 2020.

"Materials and processes of the micro and macro texturation of floor covering surfaces, optical and tribological properties"

Benoît Wittmann conducted his thesis work in PSP team under the supervision of Pierre Montmitonnet, in the framework of a CIFRE project with Tarkett company.

He will defend his PhD work in Numerical Mechanics and Materials on Dec. 17th, 2020 in front of this jury:

– M.C. Gaël OBEIN (CNAM, Saint-Denis)
– Pr.U.  Marie-Ange BUENO (Univ. de Haute Alsace-ENSISA, Mulhouse)
– D.R. Marie-Christine BAIETTO (INSA Lyon-Lamcos, Villeurbanne)
– Pr. Christian GAUTHIER (Univ. de Strasbourg, Strasbourg)
– Ing. Alain CASOLI (Tarkett Z.A. Salzbaach, Wiltz, Luxembourg)
– C.R. Alain BURR  (MINES ParisTech-CEMEF, Sophia Antipolis)
– Pr. Jean-François AGASSANT  (MINES ParisTech-CEMEF, Sophia Antipolis)
Abstract of his PhD work:
The visual aspect is a key problematic in the floor covering industry. In this thesis work, we are interested in its gloss and its time evolution with wear. First, a BRDF model (Bidirectional Reflectance Distribution Function) based on microfacets theory is developed. The novelty of this work is to compute the BRDF directly from the measured roughness of the sample. Secondly, we study the scratch resistance of the material, which is the main visually degrading damage mode. A method combining the in-situ vision of the tip/material contact, the characterization of the created cracks by tomography, and FEM simulations, allows to finely analyse the different phenomena observed experimentally. We are interested on the influence of the solicitation scale on the way the structure (coating over substrate) is deformed. Then, the scratch visibility, following the different deformation/fracture regimes observed, is studied by applying the BRDF model to the residual grooves. Finally, we propose different strategies to optimize the material by studying the influence of the substrate rheology, the coating rheology, and its thickness.
Keywords: Polymers, gloss, BRDF, tribology, scratch, tomography, FEM

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