Publication: Modelling dynamic necking instabilities in metallic ductile materials: the roles of porosity, tension-compression asymmetry and anisotropy
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2019-12
Defense date
2019-12-13
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Abstract
Ductile metals are commonly used in the manufacture of protective structures. These structures
may be submitted to impact or blast loads and their aptitude to absorb the energy of the
dynamic load is strongly related to their ability to delay the onset of plastic instabilities.
Numerous investigations, in the last two decades, have been dedicated to the study of plastic
instabilities leading to a deeper knowledge on the effect that individually inertia, strain rate,
loading path have on plastic instabilities and failure. However, the coupled influence of the
material behaviour and loading effects deserves further analysis. This doctoral thesis contributes
to the understanding of the key role played by material behaviour on the formation of dynamic
necking instabilities.We focus our attention on the role played by porosity, tension-compression
asymmetry and anisotropy. On the one hand we consider flat tensile specimens initially at rest
and subjected to dynamic uniaxial tension and elucidate, using finite element calculations, the
role of porosity and the combined role of anisotropy and tension-compression, respectively,
on the characteristics of the necking bands incepted in the specimens. On the other hand we
consider specimens subjected to dynamic loading conditions consistent with expanding rings
and tubes and bring to light, using finite element calculations and linear stability analysis, the
role played by porosity and tension-compression asymmetry, respectively, on the formation of
multiple localization patterns.
Description
Mención Internacional en el título de doctor
Keywords
Linear stability analysis, Finite element calculations, Anisotropic ductile materials, Porous ductile materials, Dynamic necking instabilities, Anisotropy, Porosity, Tension-compression asymmetry,