Computational Analysis of Quality Reduction during Drying of Lumber due to Irrecoverable Deformation. I: Orthotropic Viscoelastic-Mechanosorptive-Plastic Material Model for the Transverse Plane of Wood

Hanhijärvi, Antti; Mackenzie‐Helnwein, Peter

doi:10.1061/(asce)0733-9399(2003)129:9(996)

Cited by 38 publications

(33 citation statements)

References 18 publications

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“…While basic information about viscoelasticity is given in Nowacki (1965) and Lockett (1972) for example, bending creep tests can be found in Zhou et al (1999) and Bengtsson and Kliger (2003) or under tensile and compressive load in Toratti and Svensson (2000). Theoretical investigations concerning constitutive laws and models were studied in Kaliske (2000), Svensson and Toratti (2002), Hanhijärvi and Mackenzie-Helnwein (2003) or Fortino et al (2009).…”

Section: Introductionmentioning

confidence: 99%

Moisture-dependent, viscoelastic creep of European beech wood in longitudinal direction

Hering

Niemz

2012

Eur. J. Wood Prod.

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In the present study, the pure viscoelastic behaviour of European beech wood is analysed in the longitudinal direction at three different moisture contents. The moisture-dependent creep compliance is identified using a four-point bending test device. The viscoelastic behaviour is ascertained to be linear with moisture content and quantified by means of a Kelvin-Voigt model approach. Viskoelastisches Kriechverhalten von Rotbuche in longitudinaler Richtung bei verschiedenen HolzfeuchtenZusammenfassung In dieser Arbeit wird das viskoelastische Verhalten von Rotbuchenholz in longitudinaler Richtung bei drei verschiedenen Holzfeuchten untersucht. Mit Hilfe eines Vierpunktbiegeprüfstandes wurde die feuchteabhängige Kriechnachgiebigkeit bestimmt. Ein linearer Zusammenhang zwischen der Holzfeuchte und der Kriechnachgiebigkeit wird nachgewiesen und anhand eines verallgemeinerten Kelvin-Voigt Ansatzes quantifiziert.

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Section: Introductionmentioning

confidence: 99%

Moisture-dependent, viscoelastic creep of European beech wood in longitudinal direction

Hering

Niemz

2012

Eur. J. Wood Prod.

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“…4, it can be observed that the CCs of the sample with > 30% MC at 95 and 105 °C were only slightly greater than that at 85 °C. This is perhaps related to a more complex phenomenon, namely mechano-sorptive creep, the creep triggered by the change in MC (Hanhijärvi and Mackenzie-Helnwein 2003). Because of the noticed loss in MC, the sample with > 30% MC was greatly affected by mechano-sorptive creep above 85 °C.…”

Section: Effect Of MC On Icmentioning

confidence: 99%

“…Because of the noticed loss in MC, the sample with > 30% MC was greatly affected by mechano-sorptive creep above 85 °C. At high temperatures as obtained in kiln drying, irrecoverable deformations evolve simultaneously with mechano-sorptive creep (Hanhijärvi and Mackenzie-Helnwein 2003). Therefore, irrecoverable deformation might be developed after the creep test at 85 °C, which resulted in the non-expected CCs at 95 and 105 °C.…”

Section: Effect Of MC On Icmentioning

confidence: 99%

“…Another reason is that the potential energy of wood molecular groups rises as temperature increases, which also leads to an improvement in the mobility of molecular chain segments. The interaction between temperature and MC on the IC and CC is not a simple superposition, but rather a complex functional relationship (Hanhijärvi and Mackenzie-Helnwein 2003). Further research needs to be done to give a much better interpretation of the temperature-MC interaction effect.…”

Section: Interaction Between Temperature and MCmentioning

confidence: 99%

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Creep Behavior of Wood Plasticized by Moisture and Temperature

Jin¹,

Jiang²,

Wu³

2015

BioResources

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Moisture in wood acting as a plasticizer will strongly affect the wood's viscoelastic properties. However, achieving the desired moisture content (MC) at elevated temperatures during creep tests is difficult. The aim of this study is to accurately and systematically investigate the creep behavior of birch wood at high temperatures. Experiments were conducted using a dynamic mechanical analyzer with a relative humidity accessory coupled with polyvinylidene chloride (PVDC) film for wrapping samples. Creep behavior was examined at six MCs (0%, 6%, 12%, 18%, 24%, >30%) and 11 temperatures (5 to 105 °C). The MC of wood was strictly and accurately controlled during creep tests. Instantaneous compliance (IC) and creep compliance (CC) increased with the increase of both temperature and MC, with significant changes at higher temperatures and MCs. The effects on IC and CC were more pronounced when the subject was influenced by MC, with readings approximately three times and one time greater than those influenced by temperature, respectively. Dramatic increases in CC were found at certain temperatures and MC values. There was a complex interaction between temperature and MC on IC and CC.

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“…This simplified model uses the diffusion coefficient and the surface emission coefficient as effective model parameters, which take the variations in the flow properties into consideration and whose values are obtained through a comprehensive empirical fit to the experimental data. The model is introduced in more detail in Hukka (1996), Ranta-Maunus (1994), Hanhijärvi and Mackenzie-Helnwein (2003), and Mackenzie-Helnwein and .…”

Section: Calculation Of Case Hardeningmentioning

confidence: 99%

The Effect of Drying and Storage Conditions on Case Hardening of Scots Pine and Norway Spruce Timber

Tarvainen

Ranta-Maunus

Hanhijärvi

et al. 2006

Maderas, Cienc. tecnol.

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Case hardening is a feature of dried wood that causes the wood to deform (cup) after re-sawing and equalising the moisture content. VTT has analysed case hardening with the aid of the simulation model PEO and with experimental drying, conditioning and storage tests. Case hardening cannot be predicted by the moisture content gradient alone. However, the case hardening gap after drying to a high final moisture content of 18% is nearly identical to the calculated gap caused by cupping when the moisture gradients of the two halves of the test piece are equalised.24 hours (proposed in ENV 14464) is too little time to show the total cupping when keeping the sliced specimens in a plastic bag. Thus the test according the standard doesn't show the whole cupping tendency of, for example, panels when the moisture content is equalised after re-sawing the timber and planing the billets.Increasing the kiln drying rate increases the resulting case hardening tendency. With effective conditioning at the drying temperature, or with steaming after cooling, it is possible to reduce or remove the case hardening. But at normal temperatures in end-use or storage of timber the case hardening diminishes very slowly, despite the equalising of the moisture content in the cross-section.

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Computational Analysis of Quality Reduction during Drying of Lumber due to Irrecoverable Deformation. I: Orthotropic Viscoelastic-Mechanosorptive-Plastic Material Model for the Transverse Plane of Wood

Cited by 38 publications

References 18 publications

Moisture-dependent, viscoelastic creep of European beech wood in longitudinal direction

Moisture-dependent, viscoelastic creep of European beech wood in longitudinal direction

Creep Behavior of Wood Plasticized by Moisture and Temperature

The Effect of Drying and Storage Conditions on Case Hardening of Scots Pine and Norway Spruce Timber

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