14/02/2020

Mechanical behavior of porous materials under dynamic loading: micro-inertia effects and microstructure heterogeneities

This job offer has expired


  • ORGANISATION/COMPANY
    Université de Lorraine
  • RESEARCH FIELD
    EngineeringMechanical engineering
  • RESEARCHER PROFILE
    First Stage Researcher (R1)
  • APPLICATION DEADLINE
    29/03/2020 23:00 - Europe/London
  • LOCATION
    France › Metz
  • TYPE OF CONTRACT
    Temporary
  • JOB STATUS
    Full-time
  • HOURS PER WEEK
    35
  • OFFER STARTING DATE
    01/10/2020

Synopsys

Dynamic response of porous materials is of primary importance in numerous fields whether it concerns optimization of blast mitigation devices, collision processes in the solar system, clinical applications such as kidney stones fragmentation by shock wave lithotripsy. Under dynamic loading, ductile metals face very intense loading accompanied by high strain rates and very large magnitude of stresses. For instance, during plate impact tests, the strain rate can reach 107s-1 and the stress level can be of the order of 10 GPa. While this experimental observation has been carefully investigated in quasi-static conditions, under dynamic loading it has raised much less attention.

Such large loads trigger the development of damage by microvoiding. It has been shown that the local inertia plays a role in the development of microvoiding at high strain rates. Moreover, it is known that for moderate triaxiality, the shape of the cavity evolves upon the deformation process. In addition, porous materials generally contain voids with various initial sizes and shapes, which induce heterogeneities at the microstructure scale.

In this PhD research the goal is to propose an analytical modeling which accounts for these heterogeneities and micro-inertia effects (local acceleration fields developed at the local scale). Numerical RVE (Representative Volume Element) will be developed in order to validate the model.

Research outputs

 

A comprehensive comparison between numerical simulations and analytical models will enable to understand the role of heterogeneities present at the level of the microstructure (size and shape of voids) on the dynamic behavior of porous materials. This work will be useful to develop a better comprehensive of the damage in porous materials, in order to optimize protective devices subjected to dynamic loadings.

 

Hosting

The PhD Student will work at the University of Lorraine (in the LEM3 laboratory, Metz, France) with Professors C. Czarnota and C. Sartori in order to develop the formulation of a new constitutive

Profile

 

We are looking for highly motivated candidates who want to pursue a scientific career in mechanical engineering. An ideal candidate would have a background in mechanical engineering numerical approaches (finite element calculations).

Good communication in English is required.

Application

The candidates must provide a CV, an academic transcript of master’s degrees, a letter of motivation where they clearly state why, under their point of view, they should be enrolled in the thesis.

Key publications:

 

Czarnota C., Molinari A., Mercier S., The structure of steady shock waves in porous metals. Journal of the Mechanics and Physics of Solids. 2017; 107: 204-228.

Czarnota C., Jacques N., Mercier S., Molinari A. Modelling of dynamic ductile fracture and application to Jacques simulation of plate impact tests on tantalum. Journal of the Mechanics and Physics of Solids. 2008; 56: 1624-1650.

Czarnota C., Mercier S., Molinari A., Modelling of nucleation and void growth in dynamic pressure loading, application to spall test on tantalum. International Journal of Fracture. 2006; 141: 177-194.

Jacques N., Czarnota C., Mercier S., Molinari A., A micromechanical model for dynamic damage and fracture of ductile materials. International Journal of Fracture. 2010; 162: 159-175.

Molinari A., Mercier S. Micromechanical modelling of porous materials under dynamic loading, Journal of the Mechanics and physics of Solids. 2001; 49: 1497-1516.

Sartori C., Mercier S., Jacques N., Molinari A., On the dynamic behavior of porous ductile solids containing spheroidal voids. International Journal of Solids and Structures. 2016; 97-98: 150-167.

Sartori C., Mercier S., Jacques N., Molinari A., Constitutive behavior of porous ductile materials accounting for micro-inertia and void shape. Mechanics of Materials. 2015; 80: 324-339.

Selection process

The candidates must provide a CV, an academic transcript of master’s degrees, a letter of motivation where they clearly state why, under their point of view, they should be enrolled in the thesis to:

Christophe Czarnota (christophe.czarnota@univ-lorraine.fr) and Cédric Sartori (cedric.sartori@univ-lorraine.fr)

 

Offer Requirements

  • REQUIRED EDUCATION LEVEL
    Engineering: Master Degree or equivalent
  • REQUIRED LANGUAGES
    ENGLISH: Good

Skills/Qualifications

We are looking for highly motivated candidates who want to pursue a scientific career in mechanical engineering. An ideal candidate would have a background in mechanical engineering and numerical approaches (finite element calculations); Good communication in English is required.

Work location(s)
1 position(s) available at
LEM3 – Laboratoire d’étude des microstructures et de mécanique des matériaux, UMR CNRS 7239
France
Lorraine
Metz
57070
7 rue Félix Savart

EURAXESS offer ID: 492654

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