Woodenboxspring – Schlaf in Harmonie mit der Natur

Le projet Ressobois a pour but de développer un système de ressorts en bois pour la literie afin de répondre à la demande de la clientèle cherchant des lits 100% naturels. Au-delà du challenge fonctionnel, le projet ouvre de nouvelles portes sur la compréhension du comportement mécanique du bois sous des sollicitations hygro-thermomécaniques peu communes et explore des techniques d’usinage tridimensionnelles.Das Ziel des Projekts «Ressobois» ist es, eine Holzfederung für Betten zu entwickeln. Damit soll das Kundenbedürfnis nach Betten aus 100-prozentig natürlichen Materialen befriedigt werden. Neben der funktionellen Herausforderung eröffnet das Projekt neue Perspektiven für das Verständnis des mechanischen Verhaltens von Holz unter nicht alltäglichen hygro-thermomechanischen Belastungen und erforscht Techniken der dreidimensionalen maschinellen Bearbeitung

Natural and artificial ageing of spruce wood as observed by FTIR-ATR and UVRR spectroscopy

Spruce samples, naturally aged for 200, 400 and 500years, artificially aged by a hydrothermal treatment (at 180, 160 or 130°C, relative air humidities of 14%, 40%, or 60% and for treatment times between 1 to 50h), as well as reference samples, were analysed by Fourier transform infrared spectroscopy (FTIR) attenuated total reflection (FTIR-ATR) and ultraviolet resonance Raman (UVRR) spectroscopy. Natural ageing mostly affected the hemicelluloses and lignin, as observed from the FTIR-ATR and UVRR spectra, respectively. The UVRR spectra of the same samples after acetone extraction indicated that lignin was partially degraded and quinone structures were possibly formed. Artificial ageing at 160°C showed a significant change in the lignin structure, a well-known effect in the thermal treatment of wood, whereas treatment at 130°C did not alter the wood structure to any significant extent. Principal component analysis of the UVRR spectra confirmed that the spectra of artificially aged wood up to 160°C are dissimilar to naturally aged wood and which are also dissimilar to unaged woo

Edge and face linear vibration welding of wood panels

Edge-to-edge linear vibration welding of particle- board, OSB, MDF and plywood gives better strength than face-to-face panel welding. In general, the edge-to-edge weldline is slightly weaker than the panels itself. The face- to-face weldline is stronger than the strength of the material in the same direction

Natural and artificial ageing of spruce wood as observed by FTIR-ATR and UVRR spectroscopy

Spruce samples, naturally aged for 200, 400 and 500 years, artificially aged by a hydrothermal treatment (at 180, 160 or 1308C, relative air humidities of 14%, 40%, or 60% and for treatment times between 1 to 50 h), as well as reference samples, were analysed by Fourier transform infrared spec- troscopy (FTIR) attenuated total reflection (FTIR-ATR) and ultraviolet resonance Raman (UVRR) spectroscopy. Natural ageing mostly affected the hemicelluloses and lignin, as observed from the FTIR-ATR and UVRR spectra, respec- tively. The UVRR spectra of the same samples after acetone extraction indicated that lignin was partially degraded and quinone structures were possibly formed. Artificial ageing at 1608C showed a significant change in the lignin structure, a well-known effect in the thermal treatment of wood, whereas treatment at 1308C did not alter the wood structure to any significant extent. Principal component analysis of the UVRR spectra confirmed that the spectra of artificially aged wood up to 1608C are dissimilar to naturally aged wood and which are also dissimilar to unaged wood

Parameters of wood welding: A study with infrared thermography

Welding of wood is a well-known joining procedure that offers several advantages over traditional mechanical fasteners or gluing. During welding, extensive solid-state transformation phases occur in the so-called melting zone and the heat-affected zone. The nature and the extension of such transformations are correlated to the energy input and thus to the heat generated during the process at the wood joint interface. In the present work the influence of the welding parameters and wood grain orientation on the temperature profile and distribution and final strength of welded connections was investigated. For this purpose, the characteristics of the joints were evaluated with both destructive and non-destructive techniques. Non-destructive evaluation was performed with infrared thermography, which allowed measurement of the maximal and average peak temperature, temperature profile and distribution, and rate of temperature increase. Thus, this technique can also be used to detect welding defects and to provide information on material modification during weldin

Parameters of wood welding: A study with infrared thermography

Welding of wood is a well-known joining procedure that offers several advantages over traditional mechanical fasteners or gluing. During welding, extensive solid-state transformation phases occur in the so-called melting zone and the heat-affected zone. The nature and the extension of such transformations are correlated to the energy input and thus to the heat generated during the process at the wood joint interface. In the present work the influence of the welding parameters and wood grain orientation on the temperature profile and distribution and final strength of welded connections was investigated. For this purpose, the characteristics of the joints were evaluated with both destructive and non-destructive techniques. Non-destructive evaluation was performed with infrared thermography, which allowed measurement of the maximal and average peak temperature, temperature profile and distribution, and rate of temperature increase. Thus, this technique can also be used to detect welding defects and to provide information on material modification during welding

Natur beobachten und nachahmen

La nature est bien faite: le cèdre de Californie en est la preuve, il est le favori pour la fabrication des crayons depuis une centaine d’années chez Caran d’Ache. D’où vient cette perfection? Comment obtenir ces qualités sans devoir passer par les inconvénients de l’importation d’une essence exotique?Die Natur kann es am besten, dafür ist Kalifornisches Zedernholz der Beweis. Seit hundert Jahren favorisiert Caran d’Ache die Holzart in der Bleistiftherstellung. Woher kommt ihre Perfektion? Wie können wir diese Qualitäten erreichen, ohne eine exotische Art importieren zu müssen

Soudage linéaire du bois : étude et compréhension des modifications physico-chimiques et développement d'une technologie d'assemblage innovante.

Wood welding by linear friction allows bonding of timber in a few seconds without unsing any adhesive. The adhesion is essentially due to the wood fibres entanglements which are embedded in a melted and recured intercellular polymers matrix. But the bonding interphase formation mecanism and the machine parameters and wood substrate influences are not clearly understood.Consenquetly, the goal of this study was to analyse the different factors which are influencing the joint characteristics in order to understand the physical and mecanical process mecanism. Infrared temperature measurements brought several informations on the process. On the other hand the welded joints were caracterized by microscopy, mechanical testing, fracture mechanics, interphase and smokes chemical analysis. The results were used to developp and to verify a physical and chemical scenario describing, in successiv steps, the interphase microstructure formation. A first numerical thermal model for Fagus sylvatica was build allowing the thermal simulation of the process.The aim of the last part of the study is the understanding of the wood substrate influences on the process. The variablity problematics like those due to wood species, wood anatomy or surface quality were investigated. Modified wood and wood panels were successfully welded.The research results were applied in the frame of a preindustrial development. This has reveal new scientific and technical problematics but also a great optimization capacity of this technology.Le soudage par friction linéaire du bois permet de joindre deux pièces en bois en quelques secondes sans utiliser aucun adhésif. L'adhésion est essentiellement due à l'enchevêtrement des fibres de bois bloquées dans une matrice de matériel inter-cellulaire fondu et re-durcit. Mais le mécanisme de la formation de l'interface adhérente, l'influence des paramètres machine et de ceux du substrat sont peu connus. L'objectif de ce travail a donc été d'analyser les différents facteurs influençant les caractéristiques du joint pour comprendre les mécanismes physiques et chimiques mis en jeu lors du processus. La mesure de la température de soudage par thermographie infrarouge a apporté de multiples informations. D'autre part les pièces de bois soudées ont été caractérisées par des observations microscopiques, mécaniques, une étude du comportement à la rupture, des analyses chimiques de l'interface et des fumées. Les résultats ont permis d'élaborer un scénario physico-chimique du développement de la microstructure interfaciale et de le vérifier. Un premier modèle numérique thermique a été élaboré pour le soudage linéaire de Fagus sylvatica. La dernière partie de l'étude concerne la compréhension de l'influence du substrat. Ceci a permis d'aborder les problèmes de variabilité issus de l'essence de bois, de l'anatomie du bois ou encore de l'état de surface. Les bois modifiés et des produits dérivés du bois ont pu être soudés avec succès. Enfin les résultats de la recherche on pu être mis en application à une échelle pré-industrielle soulevant ainsi de nouvelles problématiques scientifiques et techniques mais aussi montrant un grand potentiel d'optimisation de la technologie

Potential Environmental Benefits of Ultralight Particleboards with Biobased Foam Cores

A new generation of ultralight particleboards (ULPB) with an expanded foam core layer produced in an in-line foaming step is under development. The environmental impacts of three types of ULPB containing foam based on 100% polylactic acid (PLA), 100% expanded polystyrene, and 50% PLA/50% polymethyl methacrylate, as well as a conventional particleboard (PB), have been compared in an LCA. Two approaches were chosen for the assessment: first, the “EPD-approach” in accordance with EN 15804 for EPD of building materials and second, a holistic-approach which allows an expansion of the system boundaries in order to forecast the consequences of a broader replacement of PB with ULPB. The results show that most of the environmental impacts are related to raw materials and end-of-life stages. Both approaches show that the exchange of PB with ULPB with a foam core based on PLA leads to a reduction of greenhouse gas emissions. On the other hand, the PLA is responsible for higher ecotoxicity results in comparison to non-bio-based polymers mainly due to agricultural processes. Both approaches allowed the drafting of complementary advisories for environmental impact reduction addressed to the developers