1. Figure 1. Moulding of a pipe from massive compressed wood panels
Participating countries: AT, BE, BG, CH, HR, DK, FI, FR, DE, GR, HU, IE, IT, NL, NO, PL, PT, RO, SI, SE, UK
Chair of the Action: Parviz Navi, CH,
COST Science Officer: Melae Langbein,
Thermo-Hydro-Mechanical Wood behavior and Processing
Action FP0904
Working Group 1
During Thermo-Hydrous (TH) processing, wood undergoes chemical transformations, depending upon processing parameters and wood species. Many chemical reactions may occur simultaneously within the wood constituents. To predict the performance of a product on the basis of processing parameters is a real challenge . Activities will focus on increasing and consolidating knowledge of the processes and on the characterization of TH products. Investigations will be based on the applications of Analytical Instruments and Micro-Analysis on small specimens, prepared under well defined processing conditions. To reach this objective a close collaboration with different specialist on the wood chemical modification by TH from academia and the industry is needed.
Working Group 2
Computer simulation of the molding process is a high innovative and will take an important part of the WG2 activities. Modeling will be used to understand close system THM processing of large size elements, optimizing of the parameters of the processing by virtual numerical testing, risk analysis and up scaling problems. Simulation of larger scale samples will provide opportunities for investigation heterogeneous chemical degradation, effect of heterogeneous properties, on the cracking and damaging of the element and studying the origin of the dispersion of the mechanical properties of THM wood.
Development of digital models in this area is characterized by large deformation, heat and mass transfer at high temperature and humidity. The material parameters will be collected from existing data or determined by the experiments with collaborating with the WG1. A successful introduction of a new technology to the market requires investigation of these phenomena by experiments, numerical modeling and analyzing. The vision is that this type of numerical techniques will be integrated into the wood THM industry.
Figure 1. Moulding of a pipe from massive compressed wood panels
Figure 2 . Manufacturing steps: charging, closure, pressure: Photos P. Haller
Objectives:
To improve our knowledge on the combined effect of temperature, humidity and force on the TH/THM wood.
To optimize TH/THM processing parameters during the up-scaling phase.
To develop new products based on new THM processing .
To increase long-term performance of TH/THM products.
To establish a scientific and industrial network at European as well as world-wide for TH/THM treatments.
To improve collaboration between mechanical and chemical communities.
To disseminate the information gained on TH/THM to the scientific and industrial communities. .
Working Group 3
THM-open processes are simple techniques, avoiding complex equipment used in closed system. In this technique there is less control on wood moisture content and temperature during processing. In the open system the products suffer the issues related to shape memory, wood fracturing and damage. New emerging products like wood surface densification and to some extent welded wood by friction suffer from the problems of local shape memory, reduction of crack resistance under the high moisture content. A key aspect will be to use the combination of experimentations, modeling and fracture analysis to understand how internal elastic energy typical to shape memory can be relaxed without recovery of the compression-set.
Principal Research Areas:
Investigation of the chemical degradation of wood under TH treatments, influence of processing conditions on the long-term behavior, ageing and undesired side effects.
Modelling of Thermo-Hydro-Mechanical behaviour of wood under high-temperature steam, up-scaling poblems, analysis of the risk of cracking and damages during processing, understanding the origin of the dispersion of the material properties and size effects.
Investigating the mechanisms of stress relaxation by Thermo-Hydral treatments and fixation of compression-set recovery of THM products with sound economical, ecological and functional properties