Multi-scale thermo-viscoelastic modelling of powder-based processes

Accurate modelling of powder processes requires capturing multi-physical phenomena at the particle scale. However, simulations at this size are demanding due to the high computational cost of modelling the high number of degrees of freedom represented by the discrete elements. Even though the computational analysis at the particle-particle level unveils the heterogeneity and multi-physics behaviour of powder materials, it is still prohibited the simulation of powder processes on a single high-resolution scale. This work presents a multi-scale thermal modelling approach to couple particulate-based systems with solid media using the discrete element method (DEM) and the finite element method (FEM). The implementation is built into two open-source packages, MercuryDPM [1] and oomph-lib [2], for discrete and continuum simulations, respectively. The implementation requires mapping the response of discrete particles onto a smooth, differentiable field satisfying the continuum equation of motion and energy balance. To achieve this, a bridging approach is utilized within an overlapping thermal interface that maps responses between particles and finite elements via volume
coupling enriched by a micro-macro transition technique called coarse-graining [3]. The coupled approach is validated against the analytical solutions of both unsteady heat transfer and the propagation of elastic waves through the media. As a result, advanced powder technologies can be modelled using the proposed bridging methodology, enabling efficient modelling of micro-macro scale transitions.