Elastizitätsmodul und Zugfestigkeit von Holz verschiedener Rohdichte in Abhängigkeit vom Feuchtigkeitsgehalt

Kufner, Max

doi:10.1007/bf02607685

Cited by 23 publications

(16 citation statements)

References 6 publications

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“…The ultimate Te stress σ UTS , on the other hand, is reached at ω = 5.9 % , ω = 3.3 % , and ω = 4.7 % in the L, R, and T directions, respectively, indicating a strength decline at lower MCs ( Figure 6 ). Similar findings showing that drying below a certain point leads to reduced strengths were reported (Goulet 1960 ;Kufner 1978 ;Kretschmann and Green 1996 ). Based on the mentioned references, the optimum σ UTS is reached at MCs ω ≈ 4 -12 % depending on the wood species and the orthotropic direction.…”

Section: Strength Behaviorsupporting

confidence: 81%

“…Interestingly, the influence of MC on the strength properties of wood was recognized early (Tiemann 1906 ), but a complete data set covering the strength values in Te and Co as a function of MC in all anatomical directions is not available. Yet, especially in the R and T directions, where wood strength is of great importance with regard to the load capacity and failure prediction of wooden structures, the knowledge about the moisture-dependent behavior in these directions is limited to a few references (Kollmann 1956 ;Goulet 1960 ;Kufner 1978 ;Hering et al 2012b ;Ozyhar et al 2012b ).…”

Section: Introductionmentioning

confidence: 99%

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Moisture-dependent orthotropic tension-compression asymmetry of wood

2012

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The influence of moisture content (MC) on the tension-compression (Te-Co) asymmetry of beech wood has been examined. The elastic and strength parameters, including Te and Co Young ' s moduli, Poisson ' s ratios, and ultimate and yield stress values, were determined and compared in terms of different MCs for all orthotropic directions. The results reveal a distinctive Te-Co strength asymmetry with a moisture dependency that is visualized clearly by the Te to Co yield stress ratio. The Te-Co asymmetry is further shown by the inequality of the elastic properties, known as the " bimodular behavior " . The latter is proven for the Young ' s moduli values in the radial and tangential directions and for individual Poisson ' s ratios. Although the bimodularity of the Young ' s moduli is significant at low MC levels, there is no evidence of moisture dependency on the Te-Co asymmetry of the Poisson ' s ratios.

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Section: Strength Behaviorsupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Moisture-dependent orthotropic tension-compression asymmetry of wood

2012

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“…In previous investigations tension wood was also proven to have a higher gross density than normal wood. In poplar, with a normal gross density r l of 0.43 g/cm³ (Kufner 1978), an increase of 12 to 17% for tension wood was observed frequently (for review see Sachsse 1965). The reduction of vessel frequency, leading to higher fibre density, as well as the additional, thick G-layer is assumed to cause this increase.…”

Section: Gross Densitymentioning

confidence: 99%

Microfibril Angle Distribution of Poplar Tension Wood

Lautner¹,

Zollfrank²,

Fromm³

2012

IAWA J

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Tension wood of poplar (Populus nigra) branches was studied by lightand electron microscopy. The characteristic features of tension wood such as wider growth rings, reduced vessel density and higher gross density were confirmed by our results. Based on a novel combination of transmission electron microscopy (TEM) imaging and image analysis, involving Fourier transformation, the orientation of cellulose microfibrils in the S2- and G-layer was determined. Within the G-layer microfibril angle (MFA) was parallel to the growth axis (0°). However, in the S2 it was 13° in tension wood fibres and 4° in normal wood fibres. With the exception of the relatively low fibril angle in the S2 of tension wood fibres (13°) the results are in good agreement with those of the literature.

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“…In addition, moisture-dependent wood strength, above all the tensile strength in the R and T directions, remain widely unknown for most wood species. The available data are limited to a few references [4,[8][9][10]. Since tensile stress perpendicular to the grain represents the weakest timber point [11][12][13], its knowledge, especially with regard to the load capacity and failure prediction of wooden structures, is of great importance.…”

Section: Introductionmentioning

confidence: 99%

Moisture-dependent elastic and strength anisotropy of European beech wood in tension

2012

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While the general mechanical behaviour of wood is known, its moisture-dependent elastic and strength anisotropy remains little studied. Given the anisotropic and hygroscopic nature of wood, a characterisation of wood mechanical behaviour will require knowledge of its moisture-dependent properties in relation to the three principal axes of anisotropy. The present study examines the influence of the moisture content (MC) on the elastic and strength anisotropy of beech wood (Fagus sylvatica L.). Selected elastic and strength parameters, including the anisotropic Young's moduli, Poisson's ratios, yield and ultimate stress values and the fracture toughness in the TR, TL, RT and RL directions, are determined in uniaxial tension and compact tension tests at different moisture conditions. A distinct moisture dependency is shown for the elastic and strength behaviour of beech wood. With the exception of some Poisson's ratios, all investigated elastic and strength parameters are shown to decrease with increasing MC. The two-and three-dimensional representation of the compliance matrix, and the two-dimensional visualisation of a yield surface, provides a valuable overview on the moisture-dependent elastic and strength anisotropy of beech wood.

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Elastizitätsmodul und Zugfestigkeit von Holz verschiedener Rohdichte in Abhängigkeit vom Feuchtigkeitsgehalt

Cited by 23 publications

References 6 publications

Moisture-dependent orthotropic tension-compression asymmetry of wood

Moisture-dependent orthotropic tension-compression asymmetry of wood

Microfibril Angle Distribution of Poplar Tension Wood

Moisture-dependent elastic and strength anisotropy of European beech wood in tension

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