Experimental techniques for characterization of elastic-plastic material properties in paperboard

Four experimental techniques to characterize elastic-plastic material properties for paperboard are presented. To evaluate properties as a function of paperboard thickness the bottom, middle and top plies were separated by grinding. The different plies have been characterized with respect to in-plane tension, cyclic ZD tension, out-of-plane shear and cyclic ZD compression. These tests were chosen since they are easily interpreted in term of stresses and strains, and give a good set of elastic-plastic material properties that are needed to describe the mechanical properties of the materials. For the ZD tension and compression tests several loading/unloading cycles were used in order to evaluate how the elastic modulus evolves as a function of deformation. For the ZD tension it was observed that the elastic modulus degrade faster than the strength. For all tests functions that describe the stress-strain curves are proposed and hence material parameters with a physical interpretation were introduced.