Paper physics

Kappel, Lisbeth; Hirn, Ulrich; Bauer, Wolfgang; Schennach, Robert

doi:10.3183/npprj-2009-24-02-p199-205

Cited by 25 publications

(8 citation statements)

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“…It was argued by Kappel et al [26] that the regions close to the edge of the overlap region are not likely to form chemical bonding, also if holes or regions without bonding appear within the overlap it would certainly change the stress state in the fibre-fibre interface. Furthermore, as described above, the displacement at rupture in the simulations was not necessarily equal to the displacement at rupture of the tested specimen since the work of deformation was used to scale the model response to the experimental response; the resulting discrepancies are most likely due to errors in the determination of the fibre cross-section geometry.…”

Section: Discussionmentioning

confidence: 99%

“…This is of course highly unlikely as, in general, the regions close to the edge of the overlap region are not molecularly bonded ( [25] and [26]). Also, damage development could have been included in the model, but the aim of this study was to develop a first approximation of the resultant forces and moments in the interface at rupture, and since no information on the appearance of the contact zone was known, the overlapping surfaces of the two fibres were considered to be in complete contact.…”

Section: Finite Element Discretisationmentioning

confidence: 99%

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Numerical evaluation of interfibre joint strength measurements in terms of three-dimensional resultant forces and moments

Magnusson

Östlund

2013

Cellulose

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The interfibre joint is one of the key elements in creating the strength of self-binding fibrous materials such as paper and board. In order to tailor the properties of such materials by chemical and/or mechanical treatments of the fibres, and to learn how such modifications influence the properties at the microscopic level, a greater understanding of how to evaluate the mechanical properties of interfibre joints is desirable. The methods reported in the literature for determining of the interfibre joint strength do not in general distinguish between the contributions of normal and shear stresses in the bonded region. This paper presents a numerical analysis procedure, based on the finite element method, for evaluating interfibre joint strength measurements in terms of the normal, shear, and moment loading components during testing. The method is applied to investigate the strength of Kraft pulp interfibre joints under two principally different modes of loading. The results show that for a typical interfibre joint test of an isolated fibre-fibre cross with long free fibre segments, modes of loading other than pure shear cannot, in general, be neglected, and are strongly dependent on the structural geometry of the fibre-fibre crosses. In addition, the resultant forces and moments were scaled in terms of the interface area and the twisting and bending resistance of the interface approximated as an ellipse to account for differences in interface area between the measurements. These scaled resultants were used to quantify how the mode of loading influences the relation between the amount of normal stress and the amount of shear stress that develop in the interfibre joint.

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Section: Discussionmentioning

confidence: 99%

Section: Finite Element Discretisationmentioning

confidence: 99%

Numerical evaluation of interfibre joint strength measurements in terms of three-dimensional resultant forces and moments

Magnusson

Östlund

2013

Cellulose

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“…Page 1960). Regions close to the edge of the bonding region, or even in the interior of the bonding region, may not be molecularly bonded (Page 1960;Kappel et al 2009).…”

Section: Finite Element Discretizationmentioning

confidence: 99%

A Proposed Failure Mechanism for Pulp Fiber-Fiber Joints

et al. 2016

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Due to stress concentration at the edges, fiber-fiber bonds under load are known to fail gradually inwards from the edges. In this paper, we propose a failure mechanism for fiber-fiber joints under load, based on the peak stresses occurring at the bond edges. We have modeled the mechanical testing of individual fiberfiber joints using a finite element method (FEM) framework. The model is based on experimental results of fiber-fiber joint strength tests designed to induce each of the three modes in fracture mechanics: opening, sliding, and tearing. A parametric study of the peak load at the edges of the fibers was carried out in order to identify a failure mechanism. The peak stresses were not directly taken from the FEM models, as these values are highly discretization-dependent. Instead, the peak stresses were estimated from resultant forces and moments in the bond and an idealized geometry of the bonding region. The literature has, up to now, focused on shear load as a failure mechanism for fiber-fiber bonds. However, our findings indicate that pulp fiber joints are sensitive to normal stresses and insensitive to shear stresses. Hence, we suggest utilizing failure criteria related to normal stress in future work.

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“…The specific surface area and surface charge density play pivotal roles in determining the fiber-fiber bonding strength. The former contributes to the bonded area and the latter improves shear bonding strength (Kappel et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Fiber Characteristics and Bonding Strength of Poplar Refiner-Chemical Preconditioned Alkaline Peroxide Mechanical Pulp Fractions

Li¹,

Zhang²,

Li³

et al. 2015

BioResources

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In China, alkaline peroxide mechanical pulping performed with refinerchemical preconditioning (P-RC APMP) is well known to produce fiber with high bulk, opacity, and light scattering coefficient but weak bonding and strength properties. In this study, the characteristics of different P-RC APMP fiber fractions were investigated, and their effects on bonding strength properties were determined. The results showed that there was only 5.8% R30 fiber fraction and 14.1% P100/R200 fiber fraction, and the specific surface area increased from R30 to P100/R200. The tensile index increased by 51.85% and the bonding index increased by 15.35%, when the fibers were changed from the R30 fraction to the P100/R200 fraction. The short fiber fraction (P100/R200 fraction) had smaller fiber length and coarseness but larger specific surface area and greater surface charge density than the long fiber fraction (R30 fraction). The fiber specific surface area and surface charge density made significant contributions to the bonding capacity, whereas fiber coarseness and length were negatively correlated with the tensile index.

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Paper physics

Cited by 25 publications

References 0 publications

Numerical evaluation of interfibre joint strength measurements in terms of three-dimensional resultant forces and moments

Numerical evaluation of interfibre joint strength measurements in terms of three-dimensional resultant forces and moments

A Proposed Failure Mechanism for Pulp Fiber-Fiber Joints

Fiber Characteristics and Bonding Strength of Poplar Refiner-Chemical Preconditioned Alkaline Peroxide Mechanical Pulp Fractions

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