Multiaxial dyn behavior

The objectives of the research work are to study and model the mechanical behavior, under fast-dynamic uniaxial loading, of this new category of cellular materials, TPMS "Triply Period Minimal Surface" structures, whose current state of the art is more focused on quasi-static or cyclic loading.

The work presented in this thesis is organized in three parts.

The first part aims to characterize the mechanical behavior of the constituent material, 316L steel chosen for its high ductility, produced by the SLM "Selective Laser Melting" process.

The second part of this thesis focuses on the mechanical response of TPMS structures in quasi-static and dynamic regimes. Several parameters such as relative density or type of geometry are explored in depth. The mechanical responses of the structures show the characteristics of an ideal energy absorber, with the absence of an input peak, a long, slightly ascending plateau phase and late densification. Moreover, the deformation mechanisms are stable. In the dynamic regime, the observed increase in energy absorption capacities is linked to the sensitivity of the constituent material.

In the third part, a numerical model is developed; it is capable of predicting the experimental mechanical response fairly accurately, based in particular on the material behavior laws identified beforehand. Locally, deformation occurs as a combination of several mechanisms such as buckling, bending and shearing. Energy absorption diagrams and Gibson and Ashby laws are determined with a view to relating energy absorption capacities to geometric dimensions, and thus choosing the configuration best suited to the specifications imposed.