Unravelling the deformation process of a compacted paper: in-situ tensile loading, 4D X-ray tomography and image-based analysis

• DOI: 10.1016/j.ijsolstr.2022.111539
• Publication Date: 2022-02-24T17:28:17Z
• Authors: Dan Wu; Jonas Engqvist; Christophe Barbier; Christopher Karlsson; Stephen Hall
• Keywords: Digital image correlation; Flattening; Extensibility; Tensile testing; Tension (geology); Universal testing machine

Paper of high extensibility has regained attention due to the recent increase in interest 3D paper forming for packaging. In-plane compaction been reported as an effective process improve extensibility. Though tension compacted is generally considered a reversal shrinkage, exact mechanism involved not fully studied. This study investigated mechanical behaviour by two types uniaxial tensile tests: continuous testing with digital image correlation (DIC) and stepwise in-situ within X-ray tomograph enabling 4D analysis volume (DVC). The tests were performed on notched samples taken following three orientations, parallel perpendicular main material (machine) direction at 45° this. Surface strains DIC field view covering entire sample. tomography imaging enabled observation individual fibres quantification full tensorial strain central region samples. Both confirmed existence micro-crepes fibre networks flattening tension. Incremental highest during transition between linear phases load–displacement curves tests, gradually decreased towards relatively homogeneous distribution second phase. Correlation patterns this phase location from both DVC indicates that crepes occurred mainly In later stages loading, straightening kinks observed images indicate contributions overall deformation network well form straightening.