Efficient modelling of ceramic sintering processes: Application to bilayers and membranes

The constitutive relation of Skorohod and Olevsky for viscous sintering is utilized to model the shrinkage and relative density evolution during the sintering process of ceramics. A new implicit integration scheme is presented and implemented. The computational cost is drastically reduced by combining this integration scheme with a solid-like shell element formulation, which also enables a faster and more accurate description of shape distortions, especially for thin geometries. The characterization and identification of the material viscosity is also improved via the Aquilanti-Mundim deformed Arrhenius description. The model robustness is examined with a spectrum of benchmark tests: ZnO sintering experiments from previous studies, as well as new lanthanum tungstate sintering tests. The model predictions for both dimensional shrinkage and relative density evolution are very accurate using the newly proposed material viscosity functions. The model improvements offer the possibility to simulate long-time sintering processes with higher accuracy and significantly reduced computational efforts.