Macro-and microscopic deformability of fiber networks made from softwood fibers
During tray forming, paperboard may experience failure due to locally large strains. The failures have stochastic nature and are related to the inherited inhomogeneities due to variation in anisotropy, fiber orientation, and density. As a part of the efforts to avoid these failures, a multi-scale non-linear finite element model is developed. First, the tray forming process is simulated where the paperboard is modeled on a continuum level and evaluated for failure. Based on the failure evaluation, the most critical area is modeled with a sub-model which explicitly models the paperboard fiber network, where each fiber has individual geometry and material properties. The fiber distribution and geometrical properties are based on in-line measurement on the used pulp using the tool “PupEye”. The material properties are stochastically distributed amongst the fibers. The results will show which fiber properties that should be changed to reduce the risk of failure during tray forming.