Division of Computational Methods in Nonlinear Mechanics

The research of this group is focused on the development of numerical models for powder metallurgy processes. The main research lines include:

• discrete element and multiscale modeling of powder metallurgy processes,
• simulation and optimization of manufacturing processes of ceramic, metallic and composite materials,
• experimental validation of the numerical tools,
• analysis of sintering process kinetics,
• analysis of residual stresses.

The group collaborates with several institutions and research groups in the field of the powder metallurgy experiments and composite material characterization.

Numerical modelling of powder metallurgy process

An original thermo-viscoelastic model of sintering has been developed and implemented within the framework of the discrete element method. The numerical model has been verified and validated. It has been successfully applied to simulation of real hot pressing processes of one phase powders (NiAl and Al₂O₃) and NiAl-Al₂O₃ composite.

It has been shown that the discrete element model correctly represents phenomena occurring during powder processing at the microscopic level, such as grain interaction and rearrangement or porosity decreasing, and at the macroscopic level, such as volumetric shrinkage and associated increase of bulk density. Recently, the model has been used to estimate microscopic stresses during and after the manufacture process.

Experimental studies of powder metallurgy processes

The main purpose of experimental research is to provide the essential data for calibration and validation of the numerical model of powder metallurgy. The powders are sintered and characterized at different combinations of parameters: temperature, pressure and time, in order to obtain the density vs. time curves.

Moreover, the experimental studies include mechanical and microstructural characterization of the sintered materials. Characterization of mechanical properties consists of non-destructive ultrasonic tests allowing the determination of the elastic constants of the material, and destructive studies, such as an indirect tensile strength test.