Holzforschung

Journal: Holzforschung

Publisher

De Gruyter

ISSN

0018-3830
1437-434X

Show all metadata

Search Results

Publications 1 - 10 of 64

Bacterial and abiotic decay in waterlogged archaeological Picea abies (L.) Karst studied by confocal Raman imaging and ATR-FTIR spectroscopy
Pedersen, Nanna B.; Gierlinger, Notburga; Thygesen, Lisbeth G. (2015)
Holzforschung
Waterlogged archaeological Norway spruce [Picea abies (L.) Karst] poles were studied by means of confocal Raman imaging (CRI) and attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) analysis to determine lignin and polysaccharide composition and distribution in the cell wall. The waterlogged archaeological wood (WAW) was submerged under anoxic conditions for approximately 400 years and solely decayed by erosion bacteria (EB). CRI showed that decayed tracheids contain a residual material (RM) with heterogeneous lignin distribution; within the same tracheid RM often contained regions with intensities lower than sound S2 layers up to intensity values as high as the compound middle lamella (CML). CRI revealed strong depletion of carbohydrates in RM which indicated that EB are able to utilise the carbohydrate fraction of the cell wall effectively. Raman bands assigned to lignin did not show any difference between RM and sound S2. This is a hint that EB do not modify the lignin structure. Sound WAW free from EB decay showed evidence of loss of acetyl groups in glucomannan, loss of un-conjugated ester linkages in the lignin-carbohydrate complexes between xylan and lignin, and minor oxidation of the lignin polymer compared to recent reference material. This is evidence for abiotic decay in the course of waterlogging.
A hygrothermo-mechanical model for wood: Part B. Parametric studies and application to wood welding: COST Action FP0904 2010-2014: Thermo-Hydro-Mechanical wood behavior and processing
Abbasion, Saeed; Moonen, Peter; Carmeliet, Jan; et al. (2015)
Holzforschung
The correct prediction of the behavior of wood components undergoing environmental loading or industrial process requires that the hygric, thermal and mechanical (HTM) behavior of wood are considered in a coupled manner. A fully coupled poromechanical approach has been used to perform a parametric study on wood HTM behavior, and the results have been validated with neutron imaging measurements on a moist wood specimen exposed to high temperature. Further, HTM behavior of wood during welding has been simulated by the model. For such a simulation, proper material properties are needed, as some of them, for example thermal conductivity, have a significant influence on the local and temporal behavior of the material.
Mechanical behavior of walnut ( Juglans regia L.) and cherry ( Prunus avium L.) wood in tension and compression in all anatomical directions. Revisiting the tensile/compressive stiffness ratios of wood
Bachtiar, Erik V.; Rüggeberg, Markus; Niemz, Peter (2018)
Holzforschung
The mechanical properties of walnut (Juglans regia L.) and cherry (Prunus avium L.) woods, as frequent raw materials in cultural heritage objects, have been investigated as a function of the anatomical directions and the moisture content (MC). The strength data are decreasing with increasing MC, whereas the tensile strength in the longitudinal direction is higher by factors of 1.5–2 compared to the compression strength. Moreover, the inequality of tensile and compressive stiffness is discussed, which is a matter of debate since a long time. This so-called bimodular behavior is difficult to describe in a generalized mode due to the high data variability if tension and compression properties are analyzed on different samples. If tensile and compressive stiffness tests are performed on the same samples of walnut and cherry wood, the ratio between these properties is significantly higher than 1.
Neutron attenuation coefficients for non-invasive quantification of wood properties
Mannes, David; Josic, Lidija; Lehmann, Eberhard; et al. (2009)
Holzforschung
Aspects of the Aging Process in Cambium and Xylem
Bosshard, H. H. (1965)
Holzforschung
Effect of high temperature on the change in color, dimensional stability and mechanical properties of spruce wood
Bekhta, Pavlo; Niemz, Peter (2003)
Holzforschung
Damage evolution in wood - pattern recognition based on acoustic emission (AE) frequency spectra
Baensch, Franziska; Sause, Markus G.R.; Brunner, Andreas J.; et al. (2015)
Holzforschung
Tensile tests on miniature spruce specimens have been performed by means of acoustic emission (AE) analysis. Stress was applied perpendicular (radial direction) and parallel to the grain. Nine features were selected from the AE frequency spectra. The signals were classified by means of an unsupervised pattern recognition approach, and natural classes of AE signals were identified based on the selected features. The algorithm calculates the numerically best partition based on subset combinations of the features provided for the analysis and leads to the most significant partition including the respective feature combination and the most probable number of clusters. For both specimen types investigated, the pattern recognition technique indicates two AE signal clusters. Cluster A comprises AE signals with a relatively high share of low-frequency components, and the opposite is true for cluster B. It is hypothesized that the signature of rapid and slow crack growths might be the origin for this cluster formation.
Damage evolution in wood: Synchrotron radiation micro-computed tomography (SRμCT) as a complementary tool for interpreting acoustic emission (AE) behavior
Baensch, Franziska; Zauner, Michaela; Sanabria, Sergio J.; et al. (2015)
Holzforschung
Tensile tests of miniature spruce wood specimens have been performed to investigate the damage evolution in wood at the microscopic scale. For this purpose, the samples were stepwise tensile loaded in the longitudinal (L) and radial (R) directions and the damage evolution was monitored in real-time by acoustic emission (AE) and synchrotron radiation micro-computed tomography (SRμCT). This combination is of outstanding benefit as SRμCT monitoring provides an insight on the crack evolution and the final fracture at microscopic scale, whereas AE permits the detection of the associated accumulation and interaction of single damage events on all length scales with high time resolution. A significant drawback of the AE testing of wood has been overcome by means of calibrating the AE amplitudes with the underlying crack length development. Thus, a setup-dependent and wood species-dependent calibration value was estimated, which associates 1 μm2 crack area generating of 0.0038 mV in the detected AE amplitude. Furthermore, for both L and R specimens, AE signals were classified into two clusters by using a frequency-based approach of unsupervised pattern recognition. The shares of AE signals of both clusters correlate with the ratio of the relative crack area of the interwall and transwall cracks gained from the fractographic analysis of SRμCT scans.
Moisture-induced stresses and distortions in spruce cross-laminates and composite laminates
Gereke, Thomas; Hass, Philipp; Niemz, Peter (2010)
Holzforschung
Determination of residual stress in bonded wood components
Scheffler, Michael; Weber, Tony; Niemz, Peter; et al. (2007)
Holzforschung

Publications 1 - 10 of 64

Journal: Holzforschung

Abbreviation

Publisher

Journal Volumes

ISSN

Description

Filters

Search Results