Fully resolved numerical simulations of fused deposition modeling. Part II – solidification, residual stresses and modeling of the nozzle

Abstract

Purpose -This paper continues the development of a comprehensive methodology for fully resolved numerical simulations of fusion deposition modeling. Design/methodology/approach -A front-tracking/finite volume method introduced in Part I to simulate the heat transfer and fluid dynamics of the deposition of a polymer filament on a fixed bed is extended by adding an improved model for the injection nozzle, including the shrinkage of the polymer as it cools down, and accounting for stresses in the solid. Findings -The accuracy and convergence properties of the new method are tested by grid refinement and the method is shown to produce convergent solutions for the shape of the filament, the temperature distribution, the shrinkage and the solid stresses.Research limitations/implications -The method presented in the paper focuses on modeling the fluid flow, the cooling and solidification, as well as volume changes and residual stresses, using a relatively simple viscoelastic constitutive model. More complex material models, depending, for example, on the evolution of the configuration tensor, are not included. Practical implications -The ability to carry out fully resolved numerical simulations of the fusion deposition process is expected to be critical for the validation of mathematical models for the material behavior, to help explore new deposition strategies, and to provide the "ground truth" for the development of reduced order models. Originality/value -The paper completes the development of the first numerical method for fully resolved simulation of fusion filament modeling. arXiv:1711.07094v2 [physics.flu-dyn]

Experimental validation of a numerical model for the strand shape in material extrusion additive manufacturing

“…A three-dimensional computational thermo-fluid dynamics simulation of the material deposition was performed by Dabiri et al [47] and the model was extended in [48] to include a shear-and temperature-dependent viscosity function of the polymer melt. In [49], the research was further expanded to simulate the thermal expansion of the material, the development of the thermal stresses, and the physical presence of the extrusion nozzle. Du et al [50] also presented a thermo-fluid numerical model of the polymer melt deposition in laser-assisted material extrusion AM.…”

Flow analysis of the polymer spreading during extrusion additive manufacturing

“…Comminal et al [11] used a Newtonian isotherm hypothesis and provided pressure distributions and deposit dimensions for different gaps between the head and the substrate and different fluid and printing head velocities. Xia et al [12] computed the deposit of successive layers. They used viscous and elastic behaviors in the liquid and solid phases respectively, but they did not calculate the pressure generation between the printing head and the substrate.…”

Review on process model, structure-property relationship of composites and future needs in fused filament fabrication

“…Xia et al. 106 extended their initial 3D melt flow model 67 adding a more realistic nozzle simulation. They used an immersed boundary to represent the cylindrical nozzle channel, and the melt was assumed to be extruded through the channel.…”

“…The temperature and mean stress plots at different times, (a) temperature at three times in a longitudinal cross-section through the middle of the domain, (b) mean stress in the same plane, and (c) mean stress in a perpendicular plane cutting through the middle of the bead. 106 Source: reproduced with permission from Emerald Publishing Ltd, 2018.…”