DEM model of powder flow and melting

The Déantús Advanced Manufacturing Research Centre will draw together research expertise from academia and industry to deliver innovation in additive manufacturing (AM) techniques and processes. Déantús Platform research combines novel metrology, modelling, data analytics and control theory to achieve significantly enhanced AM processing efficiency for metals and ploymers. Platform research highlights include (a) new process-structure-property models of AM, (b) novel materials, metrology and in-process data collection, (c) new technology for smart injection moulding, and (d) the application of novel cognitive computing methods to data interpretation and decision support for AM equipment operators.

Platform 2, Process-Structure Modelling, will develop and validate new models for the simulation of powder flow, metal melting, melt flow, metal solidification, and microstructure evolution, as well as constitutive models of resulting mechanical properties. In Platform 2, models of powder flow, melt flow, and solidification will combine discrete element modelling, continuum two-phase flow computational fluid dynamics, and plasticity models. To predict microstructure formation and identify columnar-equiaxed transitions, cellular automata (CA) will be applied for front tracking (FT). To couple the fluid solidification and microstructure evolution processes, a common software architecture OpenFOAM will be utilised. For mechanical property prediction, the phase field method (PFM) will be used, in combination with strain gradient crystal plasticity finite element models. Platform 2 will deliver a process-structure¬property through process model for the first time.

Project description: DEM model of powder flow and melting
The powder particles behaviour will be simulated using Discrete Element Method (DEM), where Newton’s equations of translational and rotational motion for constituent particles of the powder bed (PB) are simultaneously solved. (ii) Modelling of the PB melting including: (a) PB irradiation by a laser beam whereby the photon energy is transformed into thermal energy by absorption, (b) Powder melting, formation of a melt pool and melt pool dynamics driven by capillary and Marangoni forces, evaporation pressure, and the wetting ability of the powder particles and the previous layer; (iii) Coupling of the above into a strongly coupled fluid-solid-interaction model within a single computational framework. Development of powder flow model based on existing DEM software (LIGGGHTS), which can handle transport of powder particles with complex geometric shapes; Development of a two-phase CFD model of powder melt with trapped air in the OpenFOAM computational framework, where the Volume-Of-Fluid approach will be used to describe melting and wetting phenomena; Interaction (multi-physics) procedures for coupling DEM powder flow, heat transfer and CFD melt flow based on CFDEM (coupling between LIGGGHTS and OpenFOAM).