## 4 Results and Discussion  
Here, in this section, the finite element results of the stress state in the powder compact, both before and after unloading, are presented and discussed. The FE results from the two frictional models, Equations (1) and (2), are compared. Tensile stresses  
Figure 3: Schematic related to the finite element analysis. The powder continuum is indicated in green colour. (**Left**): Powder compact before pressing (no residual stresses are assumed here). (**Middle**): Powder compact after pressing. (**Right**): Finite element discretization (mesh). A total of 1248 solid elements are used to model the powder material. Note that due to limitations in LS-Dyna, the cylinder is not modelled as axisymmetric. Instead, two symmetry planes are introduced in order to reduce computational time and cost. might lead to unwanted cracking both during/after compaction and during sintering, which makes it necessary to improve upon the pressing tool; this is very costly and time-consuming. Obviously then, accurate predictions from simulations are an important issue for mechanical evaluation. The FE results for the compaction are depicted in Figures 4-8. In Figure 4, the relative density fields are shown before unloading with values of 0.6 and lower, which is relevant for a practical situation. These results have been shown earlier in [3] but are recapitulated here for clarity. In Figures 5-8, the results pertinent to the stress distribution before and during unloading are shown. Figure 4: Results from the FE simulations. Results for the relative material density are shown, in which the sintered density is used for normalization. The results are taken from [3] but shown here for completeness. (**Left**): Results from simulations based on the frictional model presented in Equation (1). (**Right**): Results from simulations based on the frictional model presented in Equation (2). Figure 5: Results from the FEM simulations. Results for the von Mises effective stress (MPa) are plotted at maximum pressing load. On the (**left**), results pertinent to the frictional model presented in Equation (1) are shown, and on the (**right**), results pertinent to the frictional model in Equation (2) are shown. Figure 6: Results from the FEM simulations. Results for the first principal stress (MPa) are plotted at an average material relative density of 0.44 during pressing. On the (**left**), results pertinent to the frictional model presented in Equation (1) are shown, and on the (**right**), results pertinent to the frictional model in Equation (2) are shown. Figure 7: Results from the FEM simulations. Results for the first principal stress (MPa) are plotted at an average material relative density of 0.51 during pressing. On the (**left**), results pertinent to the frictional model presented in Equation (1) are shown, and on the (**right**), results pertinent to the frictional model in Equation (2) are shown. The results shown in Figure 4 indicate that the density fields are very much dependent on the frictional description. An analysis using the Coulomb friction with a constant frictional coefficient is relatively simpler to perform but leads to lower accuracy of the results. Accordingly, any type of conclusions drawn from simulation results using a simple frictional model would not be relevant for an iterative industrial procedure, which is the main issue here. Clearly, it is then assumed that the predictions based on a pressure-dependent frictional model are more reliable, as shown in experiments presented in [2]. Regarding the additional details of the results using the density distribution, the predictions from the two frictional models are deviating initially.