VOLUME 52, ISSUE 3/2011

Part 2 of the three part publication deals with possible fields of application involving stem wood. In the area of timber construction hardwoods have a long tradition (e. g. roof structures, joists etc.), however their use has decreased due to the development of wood-based materials. Application fields are single structural elements, playgrounds, noise barriers, wood-facings or railway sleepers. Fields of interior work are doors, windows and parquet flooring. Furniture includes chairs, tables, shelves, upholstery frames and all kinds of built-in furniture. Hardwoods are commonly used for non-structural solid wood materials and ply materials (solid wood panels, plywood). The main raw material for structural timber (e. g. glued laminated timber, cross laminated timber, laminated veneer lumber), however, is still softwood due to the easier processing, the lower price and the currently valid standards. Suitable modifications such as heat treatment and impregnation help to stabilise dimensions and to expand application areas.

Rolling path squeeze profile cross-sections of a circular saw body for wood, generated by rolling forces from 1.96 kN to 19.63 kN were examined. The rolling force, as large as 14 kN, resulting in the rolling squeeze as high as 0.038 mm2, was considered to be the largest for the practical use. Low dispersion of the Rockwell hardness of the saw body examined was observed.

Quality in circular sawing significantly depends on the static and dynamic characteristics of the circular saw blade. A finite element model is presented, which is able to depict the characteristics of real, tension-rolled, slotted circular saw blades. The effects that occur during operation, such as rotation or heating caused by the cutting process, can also be included. The model is compared to analytical solutions and experimental results for verification.

Lightweight boards are defined by board’s density, so that even very different designs are grouped in this category: boards in sandwich structure as well as homogenous panels. As intense as design varies, production processes and resource use differ. To assess the environmental performance of several lightweight boards and to compare, LCA is appropriate. The analyses are based on companies information and amended by literature. Resource use of wood and other resources are taken into account as well as machine technology and energy consumption. Beside the products gaseous, liquid, and solid emissions are calculated. A comparison of different lightweight boards, and to complete likewise chipboard and fibreboard as standardised products, was done by using different LCIA ethods to underlay the ranking. As results two groups of boards with comparable environmental impacts were identified, sorting in beside the well-established board types chipboard and fibreboard.

An objective evaluation of walking sound has been for some years the subject of research and standardization. Various artificial excitation sources were investigated and found to be unsuitable. In this publication a new, at the Institute of Wood Technology Dresden (IHD) developed source is presented. The source is based on an electro-dynamic actuator and is realizing the sound excitation by defined impacts, simulating the walking. A reference to the IHD works standard IHD-W 431 (2003)(excitation by walking) is given. The development of a "silent laminate flooring" is described. In the research project, which was aided by The Federal Ministry of Economics and Technology (No: IW061108) could be shown that the improvement of the acoustical behaviour of a flooring is possible independent of its underlayment. The simultaneous compliance with mechanical requirements requires an optimization of the total floor system that can be done empirically.

The paper summarises the results of an extensive Austrian research project dealing with the fire resistance of timber frame constructions. Based on basic analyses of the thermal behaviour of building materials and their combinations as well as the results of more than 60 full-scale tests the failure time tf of gypsum plaster boards Type DF according to EN 520 (2009) and gypsum fibre boards according to EN 15283-2 (2009) has been determined. The improved design method for the separating function of timber constructions of ETH Zürich has been validated with the results of the full-scale tests. With this, a basis for the implementation of the method in the European standards was provided. The research program was part of the European wood-wisdom project FireInTimber.

For structural wood-based materials made from flakes like OSB the particle geometry is important for the board strength. But the geometry cannot yet be determined from images of the mat surface because particle shapes overlap and shapes cannot easily be separated by gray value properties. An image processing procedure is proposed to extract objects from gray value images which is sufficient for a representative size measurement. The procedure comprises an edge detector, a threshold decomposition and level filtering followed by screening of the objects by shape factors.

The classification of formaldehyde from category 3 of carcinogenic substances to category 1 (“verifiable carcinogenic”) justified by the IARC in 2004 established standards and requirements on limit and guide values for formaldehyde release. The guarantee of compliance regarding these demands calls for a control of formaldehyde release, as early as in the production process. With that said a measuring device was developed in the course of an industrial research program that determines gaseous formaldehyde continuously in a low range of concentration. Beyond that an automated determination of formaldehyde from liquid probes is possible as well.