Micro-mechanical approach with the Discrete Element Method (DEM)

Abstract :

This presentation summarises a PhD, which was done as a part of the ATHOR [1] (Advanced THermomechanical multiscale mOdelling of Refractory linings) project, supported by the European Commission [2] and in partnership with ITASCA [3] consultants at IRCER [4] laboratory, University of Limoges. Refractories are heterogenous industrial ceramics, resistant at high temperatures for which, in most cases, pre-existent microcracks within the microstructure play a key role in sustaining thermal shocks. This lecture will be about the DEM numerical simulation of such materials by considering their microstructures, heterogeneities with cracks, and their influences on fracture mechanics. The Particle Flow Code (PFC) [4] is the main numerical framework used in this study, and the flat joint model is the chosen contact model to simulate marble-liked interlocked grains of such materials. The general goal was to develop numerical models and techniques based on the DEM to investigate the role played by the microstructure of such materials in the macroscopic thermomechanical behaviour. In this way, to have an accurate micro (related to local inclusions or pores) to macro multiscale transition of elastic properties, a DEM periodic homogenisation approach is proposed. This approach is validated by comparing model materials, analytical and FEM models. In the mesoscale, a DEM model was proposed to use a statistical approach to mimic the mechanical influence of pre-existing microcracks. This technique was also validated by experimental data. Finally, to check the proposed DEM models applicability, wedge splitting test (fracturing in mode I) simulations are done to investigate the fracturing process and are qualitatively compared to DIC experimental outputs. These results could be helpful to develop DEM approaches in predicting the thermomechanical behaviour of heterogeneous materials containing numerous microcracks that could propagate simultaneously.

[1] www.etn-athor.eu

[2] https://ec.europa.eu/programmes/horizon2020/en/h2020-section/marie-sklodowska-curie-actions

[3] www.itascacg.com/software/PFC

[4] www.ircer.fr

Short bio :

I received my engineering degree from Tehran Polytechnic University (AKA. AUT) in mining and Geo-engineering in 2015. After moving to France, I have obtained my master’s degree in Geomechanics and Civil engineering from Grenoble Alpes University, co-accredited by Grenoble-INP in 2017. I have done my master’s thesis at 3SR laboratory, entitling: “Analysis of Rebound Mechanism of Rock Block on Slope: Experimental and Numerical Studies”, supervised by Prof. Pascal VILLARD. My PhD was in the framework of the European Commission Horizon 2020, Marie-Curie Action ITN-ETN ATHOR project (Advanced Thermomechanical Multiscale Modelling of Refractory Linings) in the University of Limoges and University of Leoben (Austria). In 2021, I have defended my PhD thesis, which was done in the IRCER laboratory and in partnership with ITASCA consultants, entitling: “Micro-mechanical Approach with Discrete Element Modelling (in the framework of ATHOR)” supervised by Prof. Marc HUGER and Dr. Damien ANDRE. It focused on the thermomechanical modelling and fracturing stimulation of heterogenous industrial ceramics by using the DEM approach. Afterwards, I joined the Navier laboratory (ENPC, UGE, CNRS) to pursue a Post-Doctoral position (ALLUVIUM project).

Selected publications:

Asadi, F., André, D., Emam, S., Doumalin, P., Huger, M., “Numerical Modelling of The Quasi-Brittle Behaviour of Refractory Ceramics by Considering Microcracks Effect” (Under Review)

Asadi, F., André, D., Emam, S., Doumalin, P., Huger, M., “Modelling the Elastic Properties of Bi-Phase Composites by Using Periodic Homogenisation Approach in Discrete Element Method (DEM)” (Under Submission)

Asadi, F., André, D., Emam, S., Doumalin, P., Huger, M., “Modelling microstructural aspects that enhance fracture toughness of refractory materials – Application to Wedge Splitting Test (WST)” (Under Submission)

Asadi, F., Eslami, A. and Valikhah, F. “Ground Improvement and Foundation Practice for Persian Gulf Bridge (Causeway); Bandar Abbass – Qeshm, Iran (FDM Method)”, Marine Georesources & Geotechnology. Taylor & Francis Pub., June 2016. http://dx.doi.org/10.1080/1064119X.2016.1213774