Letteratura scientifica selezionata sul tema "Sawn oak timber pieces"

The purpose of the study was to search external features of timber useful for predicting modulus of rupture (MOR) and modulus of elasticity (MOE), both in axial direction bending, valid for a wide range of beam qualities. For the study, 23 European oaks (Quercus robur L.) were felled in northwestern Spain, where most of the oak stands in the country are located. The trees were sawn and a sample of quarter-sawn planks was selected. Planed and edged specimens (5×10×200 cm) were tested to obtain MOR, MOE, apparent density, wood moisture content, percentage of sapwood, ring width, slope of grain and size and position (faces, upper and lower edge, heads) of external defects. The MOR was correlated with the maximum face and edge knot diameter. However, the correlations were not high enough to justify construction of a predictive model of mechanical behavior on the basis of maximum knot size in the piece. The MOE was correlated with the size of knots and wane. Presence of sapwood did not exhibit significant influence on strength performance. Homogeneity in ring width was negatively related to MOR and mainly to MOE. Subject headings: Bending; Mechanical properties; Stiffness; Wood beams; Wood structures.

On the basis of research of quality indicators features of formation of surface of band saws are considered, prepared under various schemes of teeth set. In a study of process of sawing of timber on bandsaw equipment factors are defined which have the greatest impact on the quality of sawn timber, depending on the wood: hardwood (oak) and softwood (pine). According to the research regression models are obtained allowing calculating the optimal modes of band equipment to ensure the required quality of sawn obtained timber.

Comparison results of visual and machine strength grading of Scots pine sawn timber from the Silesian Forestry Region in Poland. The paper presents an analysis of the strength grading results performed by two methods – visual (appearance) and machine, carried out for sawn timber obtained from the Silesian Forestry Region in Poland. Visual strength grading was performed in accordance with PN-D-94021:2013, while the machine strength grading with the use of MTG device from Brookhuis Electronics BV. As a result of the tests, it was confirmed that the machine grading results in a very small share of sawn timber classified as rejects. At the same time, during machine strength grading there were some sawn timber pieces that were not classified for any class or a reject. Based on its visual appearance, such timber elements should be graded as rejects.

In this study, the development of non-homogeneous color changes in oak timber during conventional drying and their relationship with the moisture gradient across the wood thickness were analyzed. The research was conducted on radial and tangential boards with a thickness of 38 mm, cut from two oak logs, one of sessile oak (Quercus petraea L.) and one of pedunculate oak (Quercus robur L.). A conventional drying schedule commonly used in enterprises was applied, and at specified time intervals samples were taken to determine the moisture content profile and monitor color changes on the cross sections of the samples. The findings reveal a complex relationship between the wood moisture content, the moisture content profile across the thickness, and the occurrence of color changes. Additionally, it was found that the wood of sessile oak dries slower and with less intense color changes compared to the wood of pedunculate oak. It was demonstrated that quarter-sawn boards dry slower compared to flat-sawn boards for both wood species. No differences in the appearance of non-homogeneous color between quarter-sawn and flat-sawn boards were identified.

Round timber is often used for hydraulic engineering works, but the strength grading of round logs is not as well developed as that of sawn timber. The advantages of using defined strength classes, as well as the proper selection of the raw material, could be applicable to hydraulic works as well. In this study, the methods and rules developed for sawn timber were applied to the mechanical selection of oak round logs, paying particular attention to the issue of the simplicity of grading operations and the moisture content of the timber. Both the acoustic velocity and dynamic modulus of elasticity of oak logs were measured with different instruments before performing destructive bending tests; machine settings were derived for both properties and dry and wet grading operations were simulated to compare efficiency. The use of the dynamic modulus of elasticity makes machine grading more efficient. On the other hand, the use of acoustic velocity alone is feasible and makes the procedure much faster, even if wet grading resulted in very conservative estimations. The yields obtained were similar for lower grades, but to achieve higher strength classes, the dynamic modulus was preferable. For very fast and less expensive measurements, velocity could be considered an appropriate method, as an improvement over the use of unselected material.

The number of firms involved in the production of barrels from white oak (quercus petraea L,) is small. The production of wood barrels is quite complex and with a low exploitation coefficient. We think it is in the interests of firms to know how much the coefficient of use of sawn material for these types of products is. For the study we have chosen the firm "Beha-N" in Rahovec, which mainly deals with the production of oak wood barrels. The sawn material taken in the study was of a good quality. To do the tests we used weighing methods, as its volume was difficult to measure since it was half milled. Tests were conducted for the production of barrel details with a volume of 50, 30 and 20 litters, which are most widely used by the costumers. For the realization used by the firm were taken into account the dimensions and technology. From the measurement data it turned out that the weight of the sawn timber was about 250kg. The results of these weights were exchanged in volume and percentage and they are shown in final results.

The paper presents an analysis of the influence of geographical origin and Scots pine log type on the mechanical properties of the timber sawn from them. The tested timber was sawn from logs obtained from three different forestry regions in Poland, located in the western part of the country. A batch of 150 timber pieces was obtained from each region. The cross-section had the dimensions of 40 mm × 138 mm. The timber was sawn from logs of three different types: butt, middle and top, from a fresh, mixed forest around 120 years old. The timber was dried in industrial conditions and planed four times. The values determined for the timber under research were the static modulus of elasticity in bending (MOE), and the bending strength (MOR). Moreover, timber density (DEN) was determined with the stereometric method. For all three sites, the highest average values of the tested timber properties were obtained for timber made of butt logs, and the lowest for timber made of top logs. It was concluded that the tested Scots pine properties depended on the type of log, and to limited extent, on its geographic origin. The statistical analysis revealed that the geographic origin of the logs that the tested timber was made of had a statistically significant impact on the variance of all the tested timber properties. The type of log also had a statistically significant influence on the variance of all the tested properties.

Pine timber of Polish origin intended for structural purposes is characterized by significant variability in the quality parameters. Technological suitability determined on the basis of relevant international classifications is based on the assessment of both selected mechanical and physical properties of wood. Moreover, the description of visual properties is also a valuable indicator regarding defect distribution. In the group of quality features playing a crucial role in the classification of sawn timber, there are knots, disruptions of grains, cracks, etc. Thus, the aim of the research was to determine the correlation between the presence of selected defects and the strength properties of individual timber pieces. This type of study is based on a nondestructive test method that allows for high optimization of sawn materials processing. In the case of sawn timber of Polish origin, the modulus of elasticity (MOE) determined using the sonic test is commonly used as a criterion. The research material was harvested from southern Poland. The results of the conducted studies confirmed a correlation between an increasing occurrence of particular types of defects and the results of MOE. Furthermore, as a result of the performed investigations, no significant effect of narrow surface cracks on strength properties was observed.

The article presents the results of thermo-mechanical densification tests conducted on Scots pine timber. The densification process was carried out in industrial conditions with a high-pressure press, which allowed flat compression of boards that were up to 2,5 m long. A phenomenon of elastic redeformations was observed in the densified boards after each pulse of compression. As a result of thermo-mechanical compression, the average timber moisture content dropped to 9%, and the average density increased by 13.5%, from the level of 547 to 621 kg/m3. As a result of thermo-mechanical densification, the strength class C of most Scots pine timber pieces improved. Most timber pieces that were subjected to thermo-mechanical densification have improved their strength class, C, by one (72.7% of the tested batch) or two C classes (3.6% of the batch under study).

Structural Finger-jointed (FJ) lumber is a common building material used mainly in timber construction. The paper evaluated the factors influencing structural performances of FJ Chinese fir lumber. Lumber was sawn from the logs following a pattern typically used in China to maximize the volume of recovered sawn timbers. After kiln-drying, the rough-sawed lumber was planned to 4.5 cm thick, 9.0 cm wide and 100cm long. The lumber pieces were assigned to two groups according to their dynamical MOE. FJ lumber is produced by cutting a series of sloping fingers on the end of the wood pieces to be joined and interlocking the two pieces by MDI glue. Bending and tensile strengths of FJ lumber were tested. The results show that the structural performance of the MSR FJ lumber was increased effectively after these units were machine-graded in advance and the interaction of variables should be considered in the design of finger joints.

Les travaux présentés dans cette thèse CIFRE, liant le CRAN et le CRITT Bois d'Epinal dans le cadre du projet ANR-OPTIFIN, contribuent au développement d'une chaîne de traitements pour la segmentation texture des images multimodales de pièces de bois en chêne. L'idée est de combiner des techniques d'acquisition multimodale dans le visible et le proche infrarouge (NIR) à des méthodes d'analyse de texture par matrices de covariance et de segmentation texture dans la variété Riemannienne, pour la détection des singularités et la discrimination du grain du bois. Dans le premier chapitre, nous dressons un état de l'art sur l'inspection automatisée des pièces de bois ; en portant une attention particulière aux essences de bois feuillus (e.g. chêne) dont l'inspection demeure encore un problème non résolu. Le deuxième chapitre porte sur la mise en place de la plate-forme d'imagerie multimodale (PIM) et la calibration des images couleur, niveaux de gris, directe et scatter dans le visible et des cartes d'abondance, obtenues à partir des images hyperspectrales NIR. Nous proposons une méthodologie originale pour les images scatter en optimisant les paramètres d'acquisition sur les pièces de bois en chêne. Le troisième chapitre concerne l'étude du recalage des images monomodales et multimodales et l'application d'une méthode pour la suppression de leur fond. Dans le quatrième chapitre, nous proposons une méthodologie d'analyse texture basée sur la fusion par matrices de covariance des images multimodales et/ou de leurs images texturales (LBP, nriLBP, GLCM et Gradient). Nous exploitons les matrices de covariance par des méthodes de clustering par K-moyennes et de classification supervisée par k-ppv, étendues au cas Riemannien, pour la segmentation. Dans le dernier chapitre sont présentés les résultats garantissant une segmentation pertinente et rapide des matrices de covariance. Ils sont obtenus après avoir déterminé les meilleurs paramètres de réglages des K-moyennes. Les résultats du clustering laissent apparaître que l'utilisation des images multimodales seules conduit à une segmentation optimale des singularités compactes. Ils montrent aussi l'importance de l'intégration des images texturales dans les jeux de modalités pour obtenir une meilleure segmentation des singularités de type région. Pour le grain du bois, une segmentation efficace est obtenue en utilisant les images texturales seules. Enfin, nous proposons d'appliquer les k-ppv dans la variété Riemannienne sur les modalités sélectionnées pour obtenir une segmentation plus précise
The work presented in this CIFRE thesis, associating CRAN and CRITT Bois for the ANR-OPTIFIN project, contributes to the development of an image processing chain for the texture segmentation of multimodal images of sawn oak timber pieces. The idea is to combine multimodal acquisition techniques in visible and near-infrared (NIR) range with texture analysis methods using covariance matrices and texture segmentation methods in the Riemannian manifold, for the detection of singularities and discrimination of wood grain. In the first chapter, we present a state of the art on automated inspection of wood pieces; with a special focus on hardwood species (e.g. oak) for which inspection is still an open problem. The second chapter deals with the implementation of the multimodal imagery platform (PIM) and the calibration of color, grayscale, direct and scatter images in the visible range and abundance maps, obtained from NIR hyperspectral images. We propose an original methodology for the scatter images by optimizing the acquisition parameters on sawn oak timber pieces. The third chapter concerns the study of the registration of monomodal and multimodal images and the application of a method for the suppression of their background. In the fourth chapter, we propose a texture analysis methodology based on the fusion of multimodal images and/or their textural images (LBP, nriLBP, GLCM and Gradient) by covariance matrices. We exploit the covariance matrices by K-means clustering andk-ppv supervised classification methods, extended to the Riemannian case, for segmentation. In the last chapter, we present results ensuring a relevant and fast segmentation of the covariance matrices. They are obtained after having determined the best parameters for the K-means setting. The clustering results show that the use of multimodal images alone leads to an optimal segmentation of compact singularities. They also show the importance of integrating textural images in the modality sets to obtain a better segmentation of regional type singularities. For wood grain, an efficient segmentation is obtained by using only textural images. Finally, we propose to apply k-ppv in the Riemannian manifold on the selected modalities to obtain a more accurate segmentation

Metrology and characterisation of products’ functional surfaces are of key importance in smart and sustainable manufacturing. By proper measures of resulting topography and dimension at the micro-cm level, higher process control can be achieved, leading to more efficient production with products closer to defined targets. Commercial surface metrology systems for lab- and in/on-line applications have increased in the last decades, but the wood sector has not yet benefited from this development. A better understanding of sawn wood topography combined with smart online metrology systems is expected to lead to a substantial reduction of waste in sawmill production, both by transforming waste pieces and sideboards into engineered wood products and by optimising the sawing process (e.g. by using thinner saw blades and reduced tolerances). It would also open new design possibilities and challenge the construction sector to replace today’s materials with renewable raw materials. Additionally, sawmills will be less dependent on incoming timber dimensions. This study is the first step towards a better understanding of sawn wood topography and how relevant surface features can be detected and analysed to enable the next generation of functional wood surfaces for various applications. By identifying the measuring instrument’s capability to capture surface topographical features of sawn wood, this paper discusses the requirements for efficient measurement techniques. It opens for future implementation of machine learning algorithms to in-line monitor and control the machining process. All tested metrology techniques showed promising results. To capture machining marks, the instrumentation needs to have lateral resolutions on the um level and a measurement area covering some cm; thus, the laser scanning system seemed to be a good compromise.

Some years ago a friend of mine, Stuart Mace, gave me a letter opener hand-carved from a piece of rosewood. Over his 70-some years Stuart had become an accomplished wood craftsman, photographer, dog trainer, gourmet cook, teacher, raconteur, skier, naturalist, and allaround legend in his home town of Aspen, Colorado. High above Aspen, Stuart and his wife, Isabel, operated a shop called Toklat, which in Eskimo means “alpine headwaters,” featuring an array of woodcrafts, Navajo rugs, jewelry, fish fossils, and photography. He would use his free time in summers to rebuild parts of a ghost town called Ashcroft for the U.S. Forest Service. He charged nothing for his time and labor. For groups venturing up the mountain from Aspen, he and Isabel would cook dinners featuring local foods cooked with style and simmered over great stories about the mountains, the town, and their lives. Stuart was seldom at a loss for words.His living, if that is an appropriate word for a how a Renaissance man earns his keep, was made as a woodworker. He and his sons crafted tables and cabinetwork with exquisite inlaid patterns using an assortment of woods from forests all over the world. A Mace table was like no other, and so was its price. Long before it was de rigueur to do so, Stuart bought his wood from forests managed for long-term ecological health. The calibration between ecological talk and do wasn’t a thing for Stuart. He paid attention to details. I first met Stuart in 1981. I was living in the Ozarks at the time and part of an educational organization that included, among other things, a farm and steam-powered sawmill. In the summer of 1981 one of our projects was to provide two tractor-trailer loads of oak beams for the Rocky Mountain Institute being built near Old Snowmass. Stuart advised us about cutting and handling large timber, about which we knew little. From that time forward Stuart and I would see each other several times a year either when he traveled through Arkansas or when I wandered into Aspen in search of relief from Arkansas summers. He taught me a great deal, not so much about wood per se as about the relation of ecology, economics, craftwork, generosity, and good-heartedness. I last saw Stuart in a hospital room shortly before he died of cancer in June 1993.