Effects of particle elongation on the binary coalescence dynamics of powder grains for Laser Sintering applications

Abstract

In this paper, the effects of particle shape and viscoelasticity on the binary coalescence rates of a pair of PEK HP3 particles in the Laser Sintering (LS) process are investigated in detail. PEK HP3 powder was characterised and the sintering rates were determined using Hot Stage Microscopy (HSM).On average, the neck growth rate shows a slower dynamic compared to

Mathematical modelling of coalescence of viscous particles: An overview

“…Martínez‐Herrera and Derby [ 31 ] used a front tracking method and an algebraic mesh generation to determine the moving surface. Haeri et al [ 40 ] used the volume‐of‐fluid approach for tracking the evolution of the liquid–air interface. In this method, the volume fraction function φ varies from 1 in the liquid region to 0 in the air and obeys the following equation: …”

“…The rate of neck growth of two coalescing viscous particles has been determined by solving the Navier-Stokes equations numerically, as described in several published investigations. These include finite element simulations by Jagota and Dawson, [30] Martínez-Herera and Derby, [31] Djohari et al, [32] Hooper et al, [33] Balemans et al, [34,35] and Wakai et al [36] ; by boundary elements by van de Vorst [37] and Yadha and Helble [38] ; and by finite volume methods by Kirchhof et al [39] and Haeri et al [40] These methods start from the continuity and Navier-Stokes equations for incompressible flow:…”

Viscous coalescence of unequally sized spherical and cylindrical doublets

“…[12][13][14][15][16] Several computationally demanding formulations for free surface determination, using the finite element, boundary integral and volume of fluid methods have also been proposed. [17][18][19][20][21][22][23][24][25][26][27] Experimental measurements have been carried out involving polymeric particles. 11,12,[28][29][30][31][32] The relative importance of viscous and inertia forces in coalescence of pairs of equal sized liquid droplets has been investigated theoretically and experimentally.…”

Lees-Edwards boundary conditions for the multi-sphere discrete element method

“…Recent literature indicates that constitutive models developed for spherical particles [11][12][13], appear amenable for extension to aspherical particles [14][15][16][17][18]. Moreover, it is now well established that particle morphology causes complex microstructural behaviour [19][20][21][22][23] and significantly influences the properties [24][25][26][27][28] of granular materials. Therefore, LEBCs in conjunction with Discrete Element Modelling (DEM) are indispensable for further development of more advanced constitutive models.…”