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The influence of the thermal modification process on wood machinability was investigated with four minor species of low economic importance. A set of representative experimental samples was machined to the form of disks with sharp and dull tools. The resulting surface quality was visually evaluated by a team of experts according to the American standard procedure ASTM D-1666-87. The objective quantification of the surface quality was also done by means of a three dimensions (3D) surface scanner for the whole range of grain orientations. Visual assessment and 3D surface analysis showed a good agreement in terms of conclusions. The best quality of the wood surface was obtained when machining thermally modified samples. The positive effect of the material modification was apparent when cutting deodar cedar, black pine and black poplar in unfavorable conditions (i.e., against the grain). The difference was much smaller for an easy-machinability specie such as Italian alder. The use of dull tools resulted in the worst surface quality. Thermal modification has shown a very positive effect when machining with dull tools, leading to a relevant increment of the final surface smoothness. [ABSTRACT FROM AUTHOR]

Wood is one of the oldest building materials and, thanks to its favorable mechanical and technological properties, one of the most versatile. Due to its biological nature, wooden artefacts can undergo some alteration during their service life that can be caused by mechanical, environmental or biological agents. Waterlogged and buried wood elements, present in wetlands and aquatic environments, are subject to modifications at the chemical and anatomical level, which also affect physical and related mechanical properties of the material. The possibility to predict long-term performance and the rate of modification of mechanical/physical properties of the wood material in specific environmental conditions is crucial for proper design and optimal maintenance of submerged load-bearing timber structures. Therefore, prediction models to estimate selected material properties were developed within this study. For this purpose Fourier Transform near-infrared (FT-NIR) spectroscopy and multivariate analysis based on partial least-squares (PLS) were used. The models proved to be effective to predict selected dynamic and physical parameters of waterlogged samples. However, in order to include the effect of water saturation in the material on site further research is indispensable. The possible detrimental effect on wood mechanical properties of waterlogging in differing environmental conditions is also discussed in this paper. Dynamic tests were performed on samples of two species, Quercus robur L. and Pinus sylvestris L., after 8 years of deposition in two differing sites. Additionally, the results obtained from fresh and archaeological samples were compared. No significant effects have been observed due to the depositional environment after short-term waterlogging. A more remarkable difference in the rate of the modification of dynamic and physical (density) properties can be attributed to differing natural features of the tested wooden species. It may be concluded that, in order to ensure a longer service-life of waterlogged timber structures, original wooden material should be properly selected, with regard to species, growth conditions, and log characteristics. [ABSTRACT FROM AUTHOR]

Understanding mechanisms of materials deterioration during service life is fundamental for their confident use in the building sector. This work presents analysis of time series of data related to wood weathering acquired at three scales (molecular, microscopic, macroscopic) with different sensors. By using several complementary techniques, the material description is precise and complete; however, the data provided by multiple equipment are often not directly comparable due to different resolution, sensitivity and/or data format. This paper presents an alternative approach for multi-sensor data fusion and modelling of the deterioration processes by means of PARAFAC model. Time series data generated within this research were arranged in a data cube of dimensions samples × sensors × measuring time. The original protocol for data fusion as well as novel meta parameters, such as cumulative nested biplot, was proposed and tested. It was possible to successfully differentiate weathering trends of diverse materials on the basis of the NIR spectra and selected surface appearance indicators. A unique advantage for such visualization of the PARAFAC model output is the possibility of straightforward comparison of the degradation kinetics and deterioration trends simultaneously for all tested materials. Image 1 • Multi-sensor data fusion facilitates understanding the weathering processes for diverse woods. • Multiway analysis allows capturing at best time trend. • Nested biplots are useful for combination of model loading in different modes. • A single model explains effect of wood modification, time and deterioration. [ABSTRACT FROM AUTHOR]