A discrete element framework for the numerical analysis of particle bed-based additive manufacturing processes

Abstract

This paper investigates the potential of the discrete element method to simulate the physics of particle bed-based additive manufacturing. This method naturally captures the discrete aspects of additive manufacturing processes, such as material addition. The proposed discrete element framework uses constitutive relations for loose powder, bonding kinematics and the thermo-mechanical behaviour of bonded particles. The mechanical bond interactions consist of beams that interconnect the particles. These beams are able to transfer forces as well as moments. The thermal conductive bond interactions assume an effective conductive area and density to account for the voids in the system. Simulated compression tests reveal that the macroscopic Young’s modulus and Poisson’s ratio of the bonded material are controlled by only two micro-scale parameters. Furthermore, a heat conducting rod of both powder and bonded material is simulated and compared to a continuum finite element simulation. The proposed discrete model is able to simulate a complete printing process, capturing the solid material behaviour accurately. A simulation of a printed sample shows various additive manufacturing aspects such as: the deposited powder layer, G-code input, heat source interaction, contact, bonding, thermal conduction and the accumulation of residual stresses and deformations.