PhD position at University Carlos III of Madrid - ERC Starting Grant - Multiple localization and fragmentation of thin-walled metallic tubes subjected to dynamic axial penetration

Open PhD position at University Carlos III of Madrid (ERC Starting Grant)

Tittle: Multiple localization and fragmentation of thin-walled metallic tubes subjected to dynamic axial penetration

Supervisor: José A. Rodríguez-Martínez

Synopsis: The dynamic axial penetration of thin-walled tubes allows to analyse multiple localization and fragmentation of ductile solids within a 2D framework. Complications resulting from wave propagation are virtually eliminated due to the symmetry of the problem, which reveals the true mechanical properties of the material. The sample stretches during loading until homogeneous deformation fails at large strains, leading to flow localization in the form of multiple necking bands (parallel to the axis of the tube) and subsequent fragmentation. The goal is to bring to light the relationship between the necking and fragmentation patterns, and (1) inertia effects, (2) stress multiaxiality effects and (3) mechanical behaviour of the material. Special attention will be paid to elucidate the role played by material porosity, surface roughness and anisotropy, since these are specific characteristics of additively manufactured specimens. The PhD research will include experimental and analytical work.

Research Outputs

• Axial penetration experiments with four different printed metals (and their traditionally-manufactured counterparts) to assess the mechanisms which control the localization and fragmentation behaviors of additively manufactured materials.
• Development of 3D perturbation analyses to investigate the joint effect that inertia, strain rate, porosity and anisotropy have on the onset and development of necking instabilities in thin-walled tubes subjected to dynamic axial penetration.

The final goal is to elucidate whether the material and surface defects of printed metals determine their strength, ductility and energy absorption capacity under impact loading.

Research approach: The experimental part of the research will be conducted at the University Carlos III of Madrid. The PhD student will become familiar with various experimental techniques and she/he will gain specific experience and know-how in the dynamic axial penetration of thin-walled tubes. Moreover, the ESR will carry out research stays in France, at the University of Lorraine in Metz, in the group Dynamics and Extreme Conditions (LEM3), where she/he will develop part of the 3D linear perturbation model to assess the interplay between inertia, strain rate, loading path and anisotropy in the formation of necking bands in metallic tubes subjected to axial penetration. The analysis and interpretation of the results, and the comparison between experiments and linear stability analysis will also be conducted at the UC3M. The ESR will be exposed to an international environment in which she/he will have the opportunity to meet and collaborate with prestigious scientists within the framework of Solid Mechanics.

Communication skills: good level of English. (SPANISH IS NOT REQUIRED)

Contact details: see the attached file