Back to list

VOLUME 59, ISSUE 1/2018

Shrinking and swelling of orthogonal glued timber products; Part 3: Local moisture behaviour along the edges of the plates – cross-section deformation

Language: German
Pages: 5 - 16
Authors: Thomas Moosbrugger, Theodor Guggenberger, Franz Neumüller, Andreas Neumüller

9,00 €

plus VAT
show abstract close

The local deformation behaviour of different multi-layered timber cross-sections (parallel or orthogonal layers) is discussed in this paper. Small sized test specimens were exposed to changing climatic conditions to determine the local length variations and the resulting local differential shrinking and swelling coefficients. The thickness of the outermost layers as well as the inner structural build-ups with parallel (glulam) or orthogonal (cross-laminated timber) arrangement of adjacent layers have been identified as the essential influential parameters. Taking the homogenized differential

shrinking and swelling coefficients of a CLT-panel as a basis, the global differential shrinking and swelling coefficients taking into account the panel-width dependent boundary effects were determined mathematically as weighted average.

Selective laser sintering of wood-based materials Interpretation of experimental results with the help of numer-ical simulation

Language: German
Pages: 17 - 23
Authors: Jens Wiedemann

9,00 €

plus VAT
show abstract close

In recent years, additive manufacturing processes have been perceived by the general public under the keyword “3D printing”. Since their beginnings more than 30 years ago, they have experienced a rapid development both on the application and on the materials side. Apart from a few exceptions, the use of wood did not play any major role and has been investigated within the scope of a research project using selective laser sintering (SLS). In addition to brief explanations on the experimental setup, the following article focuses on interactions between laser radiation and the building material components used. Furthermore, findings on suitable printing process parameters are presented and idealized numerical simulation calculations discussed

Development of a connector fitting for mounting without tools, using a new combination of methods for user-oriented product development

Language: German
Pages: 24 - 29
Authors: Tony Gauser, Matthias Weinert, Linda Geißler

9,00 €

plus VAT
show abstract close

One-dimensional user-oriented development methods are not sufficient for the development of products and solutions, which must meet the sometimes contradictory demands of multiple users. In fact, a multi-perspective approach is required. Such a method has been developed, applied and validated in the project “Development of tools to be mounted connector fitting [...]” by combining creative techniques and scientific methods. The functionality could be proved for a practical example. This approach could be applied particularly in the development of complex products, where between the production and intended use intermediate instances such as, for example, assembly, setup or calibration are expected.

Theory of pellet making; Part 2: Determination of the necessary length of the pressing channel

Language: German
Pages: 30 - 35
Authors: Zoltán Kocsis, Etele Csanády

9,00 €

plus VAT
show abstract close

The mechanical properties of pellets produced under high pressure depend on many factors. The most important influencing factors are the type of wood, the particle size, the moisture content, the pressing pressure, the pressing speed, the deformation holding time, the punch diameter and the press temperature. Furthermore, the ratio of the channel diameter (D) and the channel length (L) has significant influence on the pellet density due to the relative wall friction which is necessary to ensure the counter force. In rolling presses the counter pressure is ensured by wall friction forces which depend on the channel length. To our best knowledge this problem has not been treated yet in details and, therefore, a theoretical and experimental investigation was undertaken to derive a generally valid relationship to describe the above phenomenon. The obtained relationship in dimensionless form is suitable to determine the necessary channel length to given channel diameter for different pellet densities or required maximum pressure using the chips of two wood species. The obtained results are in agreement with real channel diameter/length ratios used in practice.

Review: Moisture requirements of wood decay fungi; Review on methods, thresholds and experimental limitations

Language: English
Pages: 36 - 42
Authors: Christian Brischke, Linda Meyer-Veltrup, Arved Soetbeer

9,00 €

plus VAT
show abstract close

Lignocellulose degrading fungi have the potential to cause severe damage on buildings and built infrastructure such as timber houses, bridges and a wide range of further wood products used in the outdoor environment or under humid conditions indoors. To protect organic and thus biodegradable building materials from decay it is of immanent importance to avoid high mois-ture loads in particular in terms of liquid water. Modelling fungal decay and thus the expected service life of wooden structures requires accurate information about the physiological needs of wood-destroying basidiomycetes. Within this review it is focused on different studies to determine the minimum moisture thresholds for fungal decay in laboratory tests referring to different exposure scenarios in real life. Several authors starting in the 1930s reported on experiments where wood specimens were exposed to different climates and infected with white and brown rot causing basidiomycetes. The experimental set-ups differed in external moisture supply and the way of infecting the test specimens, and consequently in the minimum thresholds determined for different combinations of wood and fungal species. Generally, it became obvious that wood-destroying basidiomycetes were able to degrade wood at high relative humidity (RH) with and without an external source for liquid water. Although the method of moist-ening the wood samples had an effect on the lower moisture thresholds obtained, it was concordantly evident that different basidiomycetes were able to cause significant decay of wood at moisture contents (MCs) considerably below fibre saturation, but thresholds seem to be species and substrate specific.

Rapid Engineering – Fast and safe product development

Language: German
Pages: 43 - 46
Authors: Dirk Siebrecht, Andreas Hänsel

9,00 €

plus VAT
show abstract close

In the product development of upholstery furniture, the often high proportion of free-form surfaces places high demands on the development and construction tools. The desired shaping and the specific design of the defined target functions require intensive development work in the three areas of the frame, upholstery and cover. Different and changing approaches to solution in this process require flexible development tools and separate tools. A very broad diversification of product models is also to be found in the sector. The challenges and possibilities involved in the use of suitable design systems as well as the technical areas involved in the development process are presented and explained in selected examples.

Microscopic method for the detection and evaluation of resin distribution in conventional industrial Oriented Strand Boards (OSB)

Language: German
Pages: 47 - 51
Authors: Eike Mahrdt, Elfriede M. Hogger, Hendrikus W. G. van Herwijnen, Jürgen Gießwein, Roland Mitter, Wolfgang Kantner, Johann Moser, Wolfgang Gindl-Altmutter

9,00 €

plus VAT
show abstract close

A novel method for the detection of resin in Oriented Strand Boards (OSB) is presented. For the method, thin section samples are stained in two steps with a halogen and fluorescent dye. Microscopic images are taken in halogen and fluorescent modus and are half automatically analysed by image processing software. As the aminoresin is stained after board production, the method is also suitable for the analysis of industrially produced boards.

Optimisation of the pigment formation by the wood-staining fungi Chlorociboria aeruginascens; Part 1: Biomass and pigment formation on agar and liquid media

Language: German
Pages: 52 - 60
Authors: Stephanie Stange, Susanne Steudler, Hubertus Delenk, Anett Werner, Thomas Walther, Thomas Bley, André Wagenführ

9,00 €

plus VAT
show abstract close

The blue-green mycological wood staining, caused by green elfcup (Chlorociboria sp.), has been in the interests of artists and scientists for several centuries. As Chlorociboria aeruginascens belongs to the slow-growing fungi, in this work it was looked for new growth substrates and cultivation methods to increase the pigment formation of this fungus. Therefor different substrates and cultivation methods are available. The aim was to find growth conditions, especially a suitable substrate, in order to provide coloured biomass and stained substrate for prospective pigment extractions and secondly to produce inoculum for a controlled wood staining. Due to its favourable properties, such as a favourable ratio of carbohydrates and total nitrogen content as well as a high content of accompanying sub-stances, orange juice was identified as a suitable medium.

Back to list