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propriétés mécaniques de treillis auxétiques hybrides

Abstract : The current industrial challenges are strongly linked to the minimization of energy costs and require the optimization of the systems used for this purpose. This is the case in the field of transports, where the reduction of on-board mass is a necessity to achieve the objectives of reducing energy expenses. Mechanical energy dissipation devices are no exception. In this context, lattice structures show high dissipation capacities with regard to their mass, and are therefore candidates for replacing mechanical parts in use. Among lattice structures, negative Poisson's ratio structures can exhibit higher dissipation than conventional structures. Nevertheless, these structures are subject to deformation modes that can affect their performance. This thesis work aimed at exploring the new possibilities brought by additive manufacturing technologies, in order to improve the specific mechanical properties of periodic lattices, especially for energy dissipation, by a hybridization strategy consisting in filling the vacant volume of the lattices with a material of different nature. First, two new auxetic lattices are introduced, their elastic and elasto-plastic properties are studied numerically via a homogenization strategy using periodic boundary conditions. Subsequently, an experimental and numerical campaign comparing mechanical properties of two polymer lattices with their elastomer-filled composite counterparts is detailed. The analysis of the compression tests shows an increase in the elastic properties of the composites, as well as an increase in the stress levels and densification strain. The delayed densification observed on the composite lattices allows a longer stress plateau, more desirable for energy dissipation applications, leading to an increase in specific energy absorption and absorption efficiency. Finally, metal lattices are manufactured by SLM before being filled with polyurethane. The resulting hybrid structures are studied both experimentally and numerically via compression tests, but also under X-ray tomography to observe the internal deformations of the lattices. Results suggest that a strong contrast in properties between the constituent materials can mitigate the increase in mechanical properties.This work confirms that hybridization can be an effective option to increase the specific mechanical properties of the lattices, including the specific energy dissipated.
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Submitted on : Tuesday, May 24, 2022 - 5:32:14 PM
Last modification on : Saturday, August 6, 2022 - 3:07:37 AM
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Frédéric Albertini. propriétés mécaniques de treillis auxétiques hybrides. Mécanique des matériaux [physics.class-ph]. HESAM Université, 2021. Français. ⟨NNT : 2021HESAE026⟩. ⟨tel-03677608⟩



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