Experimental investigation of microscale mechanisms during compressive loading of paperboard

Abstract Compression of paperboard is a common procedure during industrial package forming and better knowledge the material response needed to avoid defective packages waste. To go beyond current modelling approaches, experimental identification mechanisms underlying macroscopic stress–strain responses needed. In this study, in-situ uniaxial compression studied through synchrotron tomography at high spatiotemporal resolutions. Both microstructural evolution fibre network actual boundary conditions loading were quantified analysed. At microscale, equipment plates not perfectly flat resulting in an increasing sample-equipment contact area with loading. This is, however, shown only have small effect on form curves. The 3D strain fields showed that accumulated close sample surfaces early part process, whereafter main deformation zone shifted out-of-plane centre. walls pore volumes observed decrease (and recover partly after unloading). Regarding volume, reduction mechanism was seen be closure layers between fibres. Even if total volume dominant second stage compression, volumetric change non-negligible. Fibre wall commonly considered theoretical treatments but work suggests stored elastic energy could driver for recovery unloading.