Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

Lanvermann, Christian; Sanabria, Sergio J.; Mannes, David; Niemz, Peter

doi:10.1515/hf-2012-0171

Cited by 19 publications

(23 citation statements)

References 39 publications

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“…These instruments are widely distributed both for laboratory and practical applications, though the results are strongly influenced by surface moisture content (MC), fiber direction, temperature, or oven-dry density of wood (James 1968, Siau 1984, Siau 1995. In terms of MC determination, one has to differentiate between the sophisticated determination of MC and MC distribution by means of the expensive NMR and neutron imaging techniques (Telkki et al 2013;Javed et al 2014;Lanvermann et al 2014) in research laboratories and MC determination in the praxis. The methods based on NIR spectroscopy are better suited for the praxis (Kobori et al 2013(Kobori et al , 2014, but the stable calibration is a delicate matter.…”

Section: Introductionmentioning

confidence: 99%

Improved method based on dual-energy X-ray absorptiometry for nondestructive evaluation of solid wood moisture content

Tanaka

2015

Holzforschung

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An accurate, rapid, and convenient method is presented for moisture content (MC) determination of solid wood based on dual-energy X-ray absorptiometry (DXA). Poly(methyl methacrylate)-equivalent thicknesses (PMMA-EThs) of sugi (Cryptomeria japonica D. Don) wood blocks and pure water were measured by means of a wide range of X-ray tube voltages (20–100 kV). The ratio of the PMMA-ETh of pure water to that of wood decreased as X-ray tube voltage was increased, suggesting that an appropriate pair of tube voltages for DXA is 20 and 100 kV. According to this result, X-ray images of 30 wood samples were taken at 20- and 100-kV tube voltages, and their average PMMA-Eths from both images was determined. There was a strong negative correlation between the wet-basis MC of the wood sample and the ratio of its PMMA-Eth at 100 kV to that at 20 kV. A regression equation was developed for estimating the dry-basis MC of wood samples from their PMMA-ETh ratios. The standard error of estimate was 2.2%, which is better than those determined for electric moisture meters. This approach may lead to the development of a practical, nondestructive moisture meter for wood.

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Section: Introductionmentioning

confidence: 99%

Improved method based on dual-energy X-ray absorptiometry for nondestructive evaluation of solid wood moisture content

Tanaka

2015

Holzforschung

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“…For strain measurements, digital image correlation (DIC) will be applied. DIC is well suited for the visualization of strains with a high spatial resolution on wood surfaces (Zink et al 1995;Valla et al 2011;Keunecke et al 2012;Lanvermann et al 2014a) and wood-adhesive joints (Serrano and Enquist 2005). The expectation of the present study is that a better comprehension of stress fields in WABs due to moisture changes will contribute to adhesive developments, numerical simulations of WABs, and a better understanding of the durability of laminated timber under varying climatic conditions.…”

Section: Introductionmentioning

confidence: 87%

Measurement of moisture-related strain in bonded ash depending on adhesive type and glueline thickness

Knorz

Niemz

Kuilen³

2015

Holzforschung

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Structural wood-adhesive bonds (WAB) have to be durable while subjected to considerable stresses caused by mechanical loads and moisture content changes. To better understand the moisture-related durability of WABs, knowledge is important of how moisture changes generate strain in the bond. In this paper, strain on end-grain surfaces of bonded ash specimens was analyzed by means of digital image correlation. Strains were generated by wood shrinkage, and the evaluation was focused on shear strain (SStr). The bond lines were studied depending on the adhesive type – phenol resorcinol formaldehyde (PRF), melamine urea formaldehyde (MUF), polyurethane (PUR), and emulsion polymer isocyanates (EPI). Moreover, three different glueline (GL) thicknesses of MUF were taken into consideration. Comparing the adhesive types, SStr distributions (SStrD) were strongly influenced by adhesive elasticity. MUF and PRF bonds were quite rigid and were associated with pronounced strain amplitudes in and close to the GL together with strain dissipation reaching deep in the wood. PUR and EPI adhesives were more elastic and therefore allowed for smoother strain transition showing less distinct strain peaks. GL thickness had significant impact on SStrD. A high strain level and direct strain transition between adherends was found for the 0.01 mm GL, whereas a pronounced strain decrease was observed in the 0.1 and 0.2 mm GLs. This indicates different stress levels in the wood-adhesive interface dependent on GL thickness.

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“…Imaging techniques can be used to visualize water distributions within the wood structure, including magnetic resonance imaging (MRI) [29,[77][78][79], neutron imaging [80][81][82], and X-ray imaging [83,84]. Of these three, only MRI was used to study location of water at the cell level.…”

Section: Location and State Of Watermentioning

confidence: 99%

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

Fredriksson

2019

Forests

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Wood is a hygroscopic material that absorbs and desorbs water to equilibrate to the ambient climate. Within material science, the moisture range from 0 to about 95–98% relative humidity is generally called the hygroscopic moisture range, while the exceeding moisture range is called the over-hygroscopic moisture range. For wood, the dominating mechanisms of moisture sorption are different in these two moisture ranges; in the hygroscopic range, water is primarily bound by hydrogen bonding in cell walls, and, in the over-hygroscopic range, water uptake mainly occurs via capillary condensation outside cell walls in macro voids such as cell lumina and pit chambers. Since large volumes of water can be taken up here, the moisture content in the over-hygroscopic range increases extensively in a very narrow relative humidity range. The over-hygroscopic range is particularly relevant for durability applications since fungal degradation occurs primarily in this moisture range. This review describes the mechanisms behind moisture sorption in the over-hygroscopic moisture range, methods that can be used to study the interactions between wood and water at these high humidity levels, and the current state of knowledge on interactions between modified wood and water. A lack of studies on interactions between modified wood and water in the over-hygroscopic range was identified, and the possibility of combining different methods to acquire information on amount, state, and location of water in modified wood at several well-defined high moisture states was pointed out. Since water potential is an important parameter for fungal growth, such studies could possibly give important clues concerning the mechanisms behind the increased resistance to degradation obtained by wood modification.

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Combination of neutron imaging (NI) and digital image correlation (DIC) to determine intra-ring moisture variation in Norway spruce

Cited by 19 publications

References 39 publications

Improved method based on dual-energy X-ray absorptiometry for nondestructive evaluation of solid wood moisture content

Improved method based on dual-energy X-ray absorptiometry for nondestructive evaluation of solid wood moisture content

Measurement of moisture-related strain in bonded ash depending on adhesive type and glueline thickness

On Wood–Water Interactions in the Over-Hygroscopic Moisture Range—Mechanisms, Methods, and Influence of Wood Modification

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