Online Lecture by prof. Jose A. Rodriguez-Martinez

The effect of actual porous microstructure on the formation of dynamic necks, adiabatic shear bands and plastic shock waves

Speaker: prof. Jose A. Rodriguez-Martinez, Department of Continuum Mechanics and Structural Analysis, University Carlos III of Madrid, Spain.

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Title:
The effect of actual porous microstructure on the formation of dynamic necks, adiabatic shear bands and plastic shock waves.

Abstract:
In this talk, we present a novel microstructurally-informed finite element analysis to investigate the effect of actual porosity on the formation of dynamic necks, adiabatic shear bands and plastic shock waves in metallic materials subjected to high strain rates.
We have characterized by X-ray tomography the porous microstructure of different additively manufactured materials (aluminium alloy AlSi10Mg, stainless steel 316L, titanium alloy Ti6Al4V and Inconel 718L) with initial void volume fractions ranging from ≈0.0007% to ≈ 2%, and pore sizes varying between ≈ 6 μm and ≈110 μm.
The pore size distributions obtained from the tomograms have been fitted using a Log-normal statistical function, which has been used in conjunction with a Force Biased Algorithm to generate finite element models in ABAQUS with actual distributions of voids.

Four benchmark problems have been investigated: rapid radial expansion of rings, dynamic torsion of thin-walled tubes, collapse of thick-walled cylinders and dynamic cylindrical cavity expansion.

The finite element results provide new insights into the role of void volume fraction, voids size and voids shape on the formation of dynamic plastic instabilities for different loading rates and stress states.

Selected comparison with in-house experimental results and with calculations carried out with homogenized Gurson-type constitutive models will be shown. The outcomes of the analysis provide indications on the capacity of additively-manufactured metals to absorb energy under impact loadings.

This session was be chaired by prof. Patricia Verleysen (Ghent University)