Improved process stability in three-dimensional paper forming through numerical representation of material inhomogeneity

The aim of this research project is to improve the process stability and expand the range of applications for paper forming. The effect of inhomogeneity on the forming processes of paper is taken into consideration. With the extended knowledge of the inhomogeneous material properties and correlated mechanical properties, the material behavior is represented in a numerical model.

Motivation

Paper is already widely used in the packaging industry as a substitute for conventional polymer materials. However, with an expanded state of research into the plastic forming mechanisms of paper, many other potential fields of application could be opened up. Systematic studies of deep drawing and hydroforming forming processes have led to significant improvements in the quality of molded parts in recent years. As a frequently used approach, FEM simulation has provided a reliable prediction, but only when distinct homogeneities of the materials were present. The effect of paper inhomogeneity [1] represents a major challenge for numerical representation in FEM simulations.

Inhomogenität des Papiers: lokale heterogene Faserausrichtung und Formation von Papier (Wallmeier, Linvill, et al., 2016)
[1] Inhomogeneity of paperboard: local fiber alignment and formation (Wallmeier, Linvill, et al., 2016)

Aim

This research project has its focus on the significant influence from the inhomogeneity’s of material properties on the formability of paper. This approach involves extending the knowledge of the relationship between the inhomogeneous material properties, and the resulted mechanical properties. Based on this research strategy, the measurability of the identified characteristics will be investigated. Therefore, it is examined whether correlations between the measurement data of known procedures and methods of quality assurance with the relevant properties can be identified.

Approach

With the expanded knowledge of the inhomogeneous material properties and correlated mechanical properties, the material behavior is represented using a numerical model. The applicability of the model is to be extended by a highly automated data preparation/generation method, which transfers the measured data into the locally resolved material data [2]. Based on these methods, approaches will be developed to improve the reliability of forming processes for paper, considering the inhomogeneous material properties. The final step of the research approach is the validation of the developed design methods and procedures, furthermore the control strategies as well as the quality of the described models themselves.

Schematic representation of the digital material map
[2] Schematic representation of the digital material map for calculation of the locally resolved material data in forming simulations

Acknowledgements

The research project is funded by the German Research Foundation (DFG). In addition, thanks go to the project partners Fraunhofer-Institut für Verfahrenstechnik und Verpackung IVV.