Journal: Wood Science and Technology

Abbreviation

Wood Sci Technol

Publisher

Springer

Journal Volumes

ISSN

0043-7719
1432-5225

Description

Filters

Reset filters

Search Results

Publications 1 - 10 of 42
  • The kinetics of wooden bilayers is not affected by different wood adhesive systems
    Item type: Journal Article
    Vailati, Chiara; Rüggeberg, Markus; Burgert, Ingo; et al. (2018)
    Wood Science and Technology
    The bending of wooden bilayers in response to the change of relative humidity can be utilized to build autonomous actuation devices. For bending, the properties of the adhesive may play a crucial role in terms of humidity transfer and mechanical performance. Hence, the type of the adhesive may have an impact on the bilayer responsiveness upon humidity changes. In this study, bilayers with various sizes were fabricated and glued with five different adhesives. The same samples were exposed at first to a single desorption phase for 48 h and in a second experiment to ten de-/adsorption cycles with a cycle length of 24 h. The initial moisture contents (MC) of the bilayers differed depending on the type of adhesive. Due to the additional water uptake of the wood layers bonded with water introducing adhesives (PVAC, MUF and PRF), these bilayers had a higher initial MC than those bonded with non-water introducing adhesives (PUR and Epoxy). During the de-/adsorption cycles, the overall amplitude of bending stayed relatively constant. However, the start- and the endpoints of the movement were shifted in the first three cycles, since here, the cycle length was not sufficiently long to reach an equilibrated MC state. However, after this initial adjustment phase, the bending of the wooden bilayers was reversible and repeatable. No significant differences in the kinetics of bilayers manufactured with the different adhesive systems could be observed. Thus, the specific adhesive properties do not seem to influence the responsiveness and performance of the wooden bilayers.
  • Predicting the strength of European beech (Fagus sylvatica L.) boards using image-based local fibre direction data
    Item type: Journal Article
    Ehrhart, Thomas; Palma, Pedro; Schubert, Mark; et al. (2022)
    Wood Science and Technology
    Image-based local fibre direction data, generated based on the analysis of the medullary spindle pattern, were used to improve the prediction of the tensile strength parallel to the grain of European beech (Fagus sylvatica L.) boards. An approach to characterise the local fibre orientations in a board using a single numerical grading parameter was further developed. This parameter was used, in combination with the dynamic modulus of elasticity, to develop a regression model providing very good predictions of the experimentally determined tensile strength parallel to the grain (R2 = 0.84). Subsequently, machine-learning techniques were used to improve the strength model. Non-destructive and destructive tests were performed on (N =) 47 boards. A data (sub-) set (n = 36) was used to train different machine-learning techniques (Support-Vector Machines, Decision Tree, Random Forest, and Artificial Neural Network) using a 6-k cross-validation approach. The generalisation ability of the models was then assessed by a hold-out dataset (n = 11). The results showed that all machine-learning models presented good prediction accuracy (R2 up to 0.88 and MAPE below 8%). The support-vector machine and random forest methods showed the best performance. The combination of experimental methods with machine learning allows for a more precise strength grading of timber and, thus, can contribute to a more resource-efficient use of wood and may open new and more demanding fields for high-level timber applications in structures.
  • Water sorption mechanisms of commercial wood adhesive films
    Item type: Journal Article
    Wimmer, Rupert; Kläusler, Oliver; Niemz, Peter (2013)
    Wood Science and Technology
  • Hydroxyl accessibility in wood by deuterium exchange and ATR-FTIR spectroscopy: methodological uncertainties
    Item type: Journal Article
    Tarmian, Asghar; Burgert, Ingo; Thybring, Emil E. (2017)
    Wood Science and Technology
    The accessibility of wood hydroxyls to water is commonly studied by infrared spectroscopy after deuteration where water-interacting hydroxyls have their H exchanged for D. In this study, the hydroxyl accessibility is determined with ATR-FTIR spectroscopy after deuteration of specimens with liquid D₂O. Several factors are examined to reveal the uncertainties involved in the accessibility determination. Despite the fact that specimens were able to interact with water vapour after deuteration and drying, producing a freshly cut surface just before measurement limited the effect of re-exchange of hydroxyls and gave for most batches reproducible results.
  • Determination of Young’s and shear moduli of common yew and Norway spruce by means of ultrasonic waves
    Item type: Journal Article
    Keunecke, Daniel; Sonderegger, Walter; Pereteanu, Karol; et al. (2007)
    Wood Science and Technology
  • Shear behaviour of bond lines in glued laminated timber beams at high temperatures
    Item type: Journal Article
    Frangi, Andrea; Fontana, Mario; Mischler, Adrian (2004)
    Wood Science and Technology
  • Morphologic evolution in simulated wood densification
    Item type: Journal Article
    Ferrara, Alessia; Amando de Barros, Júlio; Koch, Sophie; et al. (2025)
    Wood Science and Technology
    This study investigates the radial densification of spruce wood using explicit finite element method simulations, focusing on the effects of various densification protocols. These protocols include quasi-static mechanical densification, transverse vibration-assisted mechanical densification, and self-densification through shrinking hydrogel fillings and their impact on the morphogenesis of folding patterns across different tissue types. The simulations incorporate the anisotropic mechanical behavior of wood tracheid walls and account for moisture and delignification effects using a hierarchical approach. Our results reveal the technological potential of targeted densification in creating tailored density profiles that enhance stiffness and strength. These insights offer valuable guidance for optimizing densification processes in practical applications.
  • Improving the thermal stability of one-component polyurethane adhesives by adding filler material
    Item type: Journal Article
    Clauß, Sebastian; Allenspach, Karin; Gabriel, Joseph; et al. (2011)
    Wood Science and Technology
  • Identification of moisture-induced stresses in cross-laminated wood panels from beech wood (Fagus sylvatica L.)
    Item type: Journal Article
    Gereke, Thomas; Schnider, Thomas; Hurst, Andreas; et al. (2009)
    Wood Science and Technology
  • Acoustic emission analysis of industrial plywood materials exposed to destructive tensile load
    Item type: Journal Article
    Ritschel, Franziska; Zhou, Yang; Brunner, Andreas J.; et al. (2014)
    Wood Science and Technology
    Several plywood materials made from spruce wood and, for comparison, solid spruce wood were investigated focusing on the sub-macroscopic damage evolution during tensile loading of the specimens. The destructive tests were simultaneously monitored by the acoustic emission (AE) method and strain field deformation measurement using digital image correlation (DIC). The bilinear interpretation of exponential defect growth identified the start of significant nonlinear behavior at 70 % of ultimate strength for all plywood materials. However, already the preceding and more stable damage evolution at lower stress levels has indicated a variation in intensity of the source mechanisms evaluated by AE energy of the detected events. Additional information on the formation of strain field concentration, which correlates with discrete accumulation in AE events and increased spreading in the distribution of AE energy, reveals the complexity of pre-damage due to the variation in cracks’ magnitude and timescales involved. The correlation between ultimate tensile strength and damage accumulation below 70 % of ultimate strength is determined, as well as the influence of layered structures on damage size shown by the percentage distribution of AE energy.
Publications 1 - 10 of 42