Thermo-Mechanical Modeling and Simulation of Powder-Bed based Additive Manufacturing of Polymers
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Powder bed-based additive manufacturing (AM) allows the realization of complex part geometries due to the combination of a layer wise built and local melting of powder material, whereby the part quality is drastically influenced by the thermal conditions. Selective laser sintering (SLS) of polymers represents a widely used AM technique. In contrast to metal AM, where the solidification of molten material appears rapidly after melting, crystallization of the molten polymer material appears slowly during the manufacturing process. It has been shown, that repeated crystallization followed by re-melting during the process may occur, which necessitates adapted crystallization models. Further, a dependency of the evolution of the crystallization front on the geometry of the specimen has been observed. Crystallization is accompanied by material shrinkage, which can lead to warpage, distortion and built up residual stresses. The present contribution extends the model presented in prior studies by a visco-elastic visco-plastic material model at finite strains, to compute not only the temperature and degree of crystallization, but also deformations and residual stresses during the additive manufacturing of polymeric parts.