Behaviour of Single Wood Fibres under Axial Tensile Strain

Page, D. H.; El-Hosseiny, F.; Winkler, Kai

doi:10.1038/229252a0

Cited by 191 publications

(67 citation statements)

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“…Tensile tests with a restriction of rotation of the samples resulted in a buckling of the cylinders. Likewise, tension buckling was observed in single fibre tests (Page et al 1971). Page and El-Hosseiny (1983) described tension buckling in thin-walled pulp fibres and explained the resistance of thick-walled fibres against buckling by the critical buckling stress, which depends on the response of the fibre to bending stresses in the cell wall.…”

Section: Resultsmentioning

confidence: 98%

“…The deformation studies in the ESEM showed that tension buckling took place in thin-walled fibres and that the probability of buckling decreased with decreasing cell size and increasing cell wall thickness. Comparing the failure pattern of the three fibre types, cracks in thinwalled cells were mainly initiated by cell folding and subsequent collapse, in the literature termed as ''tension buckling'' (Jeronimidis 1980;Pagano and Halpin 1968;Page et al 1971). With increasing cell wall thickness and decreasing cell size visible structural weak points like bordered pits or pit fields, seemed to become more relevant in terms of crack initiation.…”

Section: Resultsmentioning

confidence: 99%

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The fracture behaviour of single wood fibres is governed by geometrical constraints: in situ ESEM studies on three fibre types

2008

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In situ tensile tests were performed in an environmental scanning electron microscope (ESEM) on earlywood, transition wood and latewood cells of Norway spruce (Picea abies [L.] Karst.). In order to examine the single wood fibres in a wet state, a specially designed tensile testing stage with a cooling device was built. The fracture behaviour of the cell types was studied at high resolution while straining. Different failure mechanisms were observed for the three tissue types. The thin-walled earlywood fibres showed tension buckling which gave rise to crack initiation and resulted in low tensile strength, whereas thick-walled latewood fibres predominately failed by transverse crack propagation without fibre folding.

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Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

The fracture behaviour of single wood fibres is governed by geometrical constraints: in situ ESEM studies on three fibre types

2008

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“…A cell such as that shown in the centre of the section will buckle and then fail in tension. (Figure 9 a is redrawn from Page et al (1971). Reprinted with permission from ature.…”

Section: Discussionmentioning

confidence: 99%

“…In figure 9 a, fibres or tracheids are modelled as though they are simply helically wound tubes that buckle under tension (Page et al 1971). When scissors contact such tubes, they must also induce plastic buckling, both in the potential crack path (figure 9 b) and through the thickness of the section ( figure 9 c).…”

Section: Discussionmentioning

confidence: 99%

“…When fibres (hardwoods) or tracheids (softwoods) are subjected to tensile stresses, the helical windings of the cellulosic microfibrils in the S2 layer of their secondary cell walls (the thickest wall layer in most woods ; Dinwoodie 1981 ;Bodig & Jayne 1982 ;Fengel & Wegener 1989) produce shear stresses that tend to make the cell rotate (Pagano et al 1968). Constraints around these cells prevent this rotation, and the resultant instability, even at low strains, causes the walls to buckle into the lumen, the effect depending on the angle of microfibril lay-up (Page et al 1971). This effect may be restricted to cells through which the main crack passes but, despite this, Jeronimidis (1980) argues that most of the toughness of woods derives from work done in this way.…”

Section: Introductionmentioning

confidence: 99%

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The toughness of secondary cell wall and woody tissue

Lucas

Tan

Cheng

1997

Phil. Trans. R. Soc. Lond. B

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SUMMARYThe ' across grain ' toughness of 51 woods has been determined on thin wet sections using scissors. The moisture content of sections and the varying sharpness of the scissor blades had little effect on the results. In thin sections ( 0.6 mm), toughness rose linearly with section thickness. The intercept toughness at zero thickness, estimated from regression analysis, was proportional to relative density, consistent with values reported for non-woody plant tissues. Extrapolation of the intercept toughness of these woods and other plant tissues\materials to a relative density of 1.0 predicted a toughness of 3.45 kJ m −# , which we identify with the intrinsic toughness of the cell wall. This quantity appears to predict published results from IC tests on woods and is related to the propensity for crack deflection. The slope of the relationship between section thickness and toughness, describing the work of plastic buckling of cells, was not proportional to relative density, the lightest (balsa) and heaviest (lignum vitae) woods fracturing with less plastic work than predicted. The size of the plastic zone around the crack tip was estimated to be 0.5 mm in size. From this, the hypothetical overall toughness of a thick ( 1 mm) block of solid cell wall material was calculated as 39.35 kJ m −# , due to both cell wall resistance (10 %) and the plastic buckling of cells (90 %). This value successfully predicts the toughness of most commercial woods (of relative densities between 0.2 and 0.8) from ' work area ' tests in tension and bending. Though density was the most important factor, both fibre width\fibre length (in hardwoods) and lignin\cellulose ratios were negatively correlated with the work of plastic buckling, after correcting for density. At low densities, the work of plastic buckling in the longitudinal radial (LR) direction exceeded that in longitudinal tangential (LT), but the reverse was true for relative densities above 0.25. This could be attributed to the direction of rays. Density for density, the toughness of temperate hardwoods tested was about 20 % lower than that of tropical hardwoods. This is probably due to the much greater number of vessels in temperate hardwoods. Vessels appear either not to display buckling behaviour during fracture at all or to collapse cheaply. These general results have applications to other plant tissues.

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