Multiscale Material Modeling

Granular materials are the second most manipulated materials across all industries, only after water. These materials include, but are not limited to, fine powders used in cosmetic industry, compacted powders used as medical tablets in pharmaceutical industry, grains (e.g. wheat and corn) stored in silos, different types of soils, and bonded granular materials such as rocks, concrete, and asphalt used in construction industry. Moreover, consumption of these materials have hugely important effects on every aspect of life in our planet. Currently, the global rate of production of concrete stands at about 20 trillion kg per year, which contributes to about 10% of worldwide CO2 production. This ubiquitous presence of granular materials across different industries, combined with their effects on various fields demonstrates the necessity of understanding their behavior in a manner that is not only consistent with their microstructure, but is also computationally efficient, enabling analysis of real size problems. It is, therefore, clear that developing a better understanding of the behavior of granular materials at micro-level and enabling material design with more desired properties has vital environmental and economic importance.

During the past 6 years, we have developed two methodologies for deriving the behavior of both un-bonded granular materials (such as soils and grains stored in silos) and bonded granular materials (such as pharmaceutical tablets and concrete). The first approach, Particle Mechanics Approach (PMA), studies the contact between all particles and derives the behavior by enforcing equilibrium on every particle (Figure 1). The second approach, Granular Micromechanics Approach (GMA), derives materials’ behavior using a statistical analysis of inter-particle contacts in different directions (Figure 2). Combining these two approaches, will enable us to derive the behavior of materials at a desired level of accuracy and computing time.

     In the proposed project, we will use the already developed PMA code for analyzing large assemblies of particles. We will apply various types of loadings and the PMA code will provide all inter-particle forces and displacements as output. We will then use these values to (1) find valuable information about the statistical distribution of inter-particle forces as well as the directional distribution of forces, displacements, and stiffness coefficients of particle contacts (2) derive the macroscopic behavior of the assembly in terms of stress, strain, and stiffness tensors (3) use results of part 2 to improve GMA. These results will enable us to bridge the gap between macroscopic behavior of granular systems and grain properties, a link which is currently missing in the topic of multiscale material modeling.

Requirements:

• Ability to work with MATLAB
• Basic knowledge of strength of materials and solid mechanics
• Passionate to learn new topics in the area of micromechanical material modeling and publishing results

Our offer:

• Mentoring of the whole Master thesis at the institute
• Promising research topic (previous results derived by my previous Masters students are already published)
• Participation in fundamental research with wide ranging applications in different fields
• Presentation of your work in international conferences

Contact:
TU Graz, Institute of Strength of Materials
Payam Poorsolhjouy, PhD
+43 (0)316 873 7664
payam.poorsolhjouy@tugraz.at