Abstract
This work presents a numerical modelling approach of particle packing consolidation, at the particle scale, based on specific numerical methods implemented in a high-performance computing framework. Typically, the sintering process triggers several mass transport paths, thermally activated, that are driven by geometrical as well as physical gradients and laplacians. Computing precisely such major characteristics is of paramount importance but represents a real scientific challenge, which have not been fully solved yet but which must however be tackled to gain precious insights into sintering mechanisms which are seldom accessible at this scale. An Eulerian-based formulation is then proposed here to deal with the strong topological changes related to particle sintering. Also, a specific attention is paid to the precise and robust computation of high-order derivatives which are known to control the physics of surface solid diffusion, namely the surface laplacian of the curvature. Besides, the hydrostatic pressure gradient is known to control the volume diffusion path, it results from the coupled fluid-solid mechanical equilibrium, including surface tension, which must be solved precisely. Furthermore, a mesh adaptation technique allows the particles surface description to be improved, while the number of mesh elements is kept reasonable. Once verified on test-cases, this numerical approach is applied to several 3D granular packings undergoing micro-structural changes under combined surface and volume diffusion.
Highlights
Sintering process is, nowadays, a very important industrial process used for the manufacturing of countless materials and solid parts
From a macroscopic point of view, it is very difficult to develop a model taking into account all the different variables that have an impact on the evolution of the structure during sintering
Sintering is a very complex process and several challenges should be handled in order to simulate the sintering process at the particle scale
Summary
Nowadays, a very important industrial process used for the manufacturing of countless materials and solid parts. There are several unanswered questions about the underlying physical phenomena on sintering, this work represents a step toward a better understanding on the sintering process through surface and volume diffusions, and to a least extent the effects of the grain boundary diffusion This approach at the local scale is conceivable because the frame of high performance computing was considered from the onset. Concerning the sintering simulation at the particles scale, different numerical approaches are available in literature Among those models there are some analytical laws which allow to predict the growth of the neck between two particles. In order to introduce the volume diffusion into the numerical approach proposed, the pressure field inside the particles has to be computed Taking into account this pressure computation, the numerical strategy for the sintering simulation for volume diffusion will be presented in Sect. The coupling between the volume diffusion and the surface diffusion will be presented in Sect. 7, as well as the bases for the grain boundary diffusion
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