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Bu çalışma, kaynaklanmış Göknar, Meşe ve Kestane odunlarının morfolojik analizlerini tanımlamak için taramalı elektron mikroskopu ve selüloz kristanilitesini tahmin etmek için X-ışını kırınım analizi kullanılarak örnekler karakterize edilmiştir. Sonuçlar, XRD analizinde selüloz kristalinite indeksinin (CRI) göknar, meşe ve kestane ağacı örneklerinde sırasıyla% 57.55 ve % 47.73 ve% 56.66 olarak belirlendiğini göstermiştir. Tüm ahşap örneklerinin CRI değeri, kaynağa tabi tutulduktan sonra artmıştır. SEM analizine göre ahşabın genel hücre yapısı, kendini korurken kaynaklı ara fazı oluşturmak için kullanılan yüksek sıcaklık ve basınçla kırılma meydana gelmiştir. Sonuç olarak, yumuşak ağacın kristal değerinin, sert ağaçlardaki yüksek polisakkarit yüzdesine kıyasla daha yüksek olduğu bulunmuştur.

Aim of study: In this study, it was aimed to determine the shear strength after water immersion and observe bond-line density of the welded birch wood. Material and methods: 24 welded samples of dimensions 200x20x20 mm3 (LxTxR) were prepared from sapwood of birch wood (Betula pendula). Shear strength of welded birch at 24h and 48h water soaking were investigated.X-Ray CT-scanning was used to monitor the density profile of welded bond-line. Main results: The results showed that shear strength decreased slightly with increasing water immersion time. The decreasing of the average shear strength, caused by immersion for 24h and 48h were 60.25% and 78.9%, respectively, compared to control sample. With the welding process, a significant change in density was observed in the welding bond-line. As a result, the X-Ray CT scanner shows that it works effectively on wood material. Highlights: The results of this research revealed the applicability of a new method alternative to traditional mechanical fasteners (nail, screw etc.) or gluing. The availability of welding combining method in the field of wood engineering should be explored widely and more studies are recommended for appropriate parameters.

This study presents a novel application of the Wilhelmy plate method on welded joints of Scots pine sapwood and beech. Welding resulted in an increase in the contact angle (increased hydrophobicity) as well as a decrease in the water uptake and swelling of the welded pine-joint compared to non-welded pine. When the welding time was extended from 4 to 5 s, these properties were further pronounced. Welding of beech, on the other hand, led to an increase in the contact angle and a decrease in the water uptake, but an increase in the swelling. Fourier Transform Infrared spectroscopy showed that welding increased the aliphatic C–H and unsaturated C=C stretching absorption bands in pine and beech. Scanning electron microscopy showed a dense structure at the welded joints of the both species, giving evidence of a lower porosity that leads to a lower permeability as a result of the welding.

The use of wollastonite as a natural additive for the welding of Scots pine improved the water resistance and shear strength of the welded joint. The X-ray computed tomography images revealed that the welding of Scots pine with wollastonite could postpone crack formation in the welded joints. The specimens welded for a longer time (5 s) had a more uniform distribution of wollastonite particles in welded joints. The microstructure of the wood and the thickness of the wood cell walls also had a great influence on the thickness and strength of the welded joints. Water immersion tests showed that the use of wollastonite in wood joints was able to meet the requirement of resistance to frequent short-term and long-term exposure to water.

The classification of roundwood is inextricably linked to the measurement of a particular single wood defect. The appearance, location, and number of defects are important in the quality evaluation...

This paper reports the results of a novel approach using nano X-ray computed tomography (CT) for the non-invasive determination of the weld-line density profile of welded wood joints. As a case study, wood samples with a dimension of 2 mm × 2 mm × 20 mm were cut from a board of welded beech (Fagus sylvatica L.). The spatial resolution of the X-ray scan was 500 nm. Densitometry results showed that welding was accompanied by a considerable increase in the bulk density and a decrease in the cell-wall density at the weld-line. The cell-wall density in the weld-line was almost 33% less than that of the unaffected wood. As an additional application of nano computed tomography, the 3D imaging also revealed details of the internal structure of the welded sample. This study showed that nano-CT is a powerful tool for the descriptive and quantitative study of welded wood.

Most of the cracks are caused by changes in temperature and relative humidity which lead to shrinkage and swelling of the wood and thereby induce stresses in the structure. How these cracks influence the strength of the wooden structure, especially the shear strength, is not well understood. However, it is reasonable to expect that cracks have an impact on the shear strength as they preferably run along the beams in the direction of grain and bond lines. The purpose of this study was to investigate the load-bearing capacity of cracked glulam beams and to find a model that could predict the failure load of the beams due to the cracks. Three-point bending tests were used on glulam beams of different sizes with pre-manufactured cracks. An orthotropic elastic model and extended finite element method was used to model the behaviour of the cracked beams and to estimate the load-bearing capacity. The conclusions were validated by numerical simulations of the mechanical behaviour of three-point bending of...

Finite element numerical analyses were performed to determine three-dimensional heat flux generated by friction to wood pieces during linear friction welding. The objective was to develop a computational model to explain the thermal behaviour of welded wood material rather than experimental methods, which are usually expensive and time consuming. This model serves as a prediction tool for welding parameters, leading to optimal thermo-mechanical performance of welded joints. The energy produced by the friction welding of small wood specimens of Scots pine (Pinus sylvestris L.) was determined by thermocouples and used as input data in the model. The model is based on anisotropic elasticity and the thermal properties were modelled as isotropic. This numerical simulation gave information on the distribution of the temperature in the welding interface during the entire welding process. A good agreement between the simulation and experimental results showed the appropriateness of the model for planning ...

Previous investigations on linear welded woods have shown that the connections are not sufficiently resistant to water for use in outdoor conditions. Therefore, they are utilized mainly for non-structural use, with only short time exposure to varying humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood or sapwood on crack formation in the weldline of Scots pine (Pinus sylvestris) were investigated. Axial samples measuring 200 mm × 20 mm × 20 mm from Scots pine were welded, placed vertically in 5-mm-deep tap water and were taken out of the water one at a time after each 10 min of water absorption. Then they were scanned and put back into water until the first crack appeared in the weldline. An X-ray Computer Tomography (CT-) scanner was used to monitor water movement and density change in the weldlines during water absorption–desorption. CT-scanning enabled to detect the cracks as they formed in the weldline and could be used in wood welding...

The mechanical performance of welded wood has a decisive role in its applications. This study was performed to determine the welding conditions that optimized the tensile-shear strength of welded Scots pine (Pinus sylvestris). Tensile-shear strength as a function of welding pressure, welding time and holding time was measured according to European standard EN 205. Maximum tensile-shear strength of welded sample was 9.3 MPa that was obtained using 1.3 MPa welding pressure, 2.8 s welding time and 70 s holding time. This tensile-shear strength was about two times that of PVAc-glued samples. According to data evaluation tensile-shear strength could be optimized to 9.7 MPa by increasing the welding time to 3.5 s and decreasing the holding time to 60 s.

This study was performed for a better understanding of water effect on welded wood and improving its water resistance. In this article, we have also attempted to demonstrate the feasibility of usin ...

Wood welding is an environmentally-friendly and very quick technique to yield wood joints in just a few minutes and without using any adhesives. The only limitation of welded wood is that the joint is suitable only for interior use. Exterior use, or use in an environment with varying humidity requires water resistance of the welded joints. An investigation was performed to determine the effects of welding parameters and wood properties on water absorption in the weldline and how to reduce it through controlling the production parameters. The influences of welding pressure, welding time, and heartwood/sapwood on water absorption in the weldline of Scots pine (Pinus sylvestris) joints were investigated. Specimens composed of two pieces of heartwood or sapwood, each of dimensions 200 mm × 20 mm × 20 mm, were welded together to form specimens of dimensions 200 mm × 20 mm × 40 mm. The specimens were allowed to stand in 5-mm-deep tap water and then they were taken out of the water one at a time and scanned in 1...

Exterior use of welded wood laminates without further treatment is not recommended. Frictional welded joints have poor resistance to moisture variation, especially to drying. Therefore, application of welded woods is limited to interior use without exposure to highly variable air humidity. Influences of some welding and wood parameters such as welding pressure, welding time and heartwood/sapwood on weldline density of Scots pine (Pinus sylvestris) joints were investigated. Interdependence between density and water resistance of weldline (in terms of crack time) was also studied by comparing the results of this investigation with those of the earlier studies. Specimens composed of two wood pieces, each measuring 20 mm × 20 mm × 200 mm, were welded together to form a specimen measuring 40 mm × 20 mm × 200 mm by a vibration movement of one wood surface against another at a frequency of 150 Hz. An X-ray Computerized Tomography scanner was used to measure weldline density. Weldlines of sapwood produced by 1.3 ...

The industrial application range of welded wood so far has been limited to interior use because of its poor moisture resistance. Influences of some welding and wood parameters such as welding pressure, welding time, and heartwood/sapwood on water resistance of Scots pine (Pinus sylvestris) were investigated. An X-ray Computed Tomography scanner was used to monitor density change in weldlines during water absorption–desorption. Axial samples measuring 200 mm × 20 mm × 20 mm from Scots pine were welded and placed standing in 5-mm-deep tap water. Then they were taken out of the water one at a time and scanned at 10-min intervals until the first crack appeared in the weldline where the two parts of each specimen made connection. Results showed that the X-ray Computed Tomography can be used as an effective tool to study welded wood. Welding pressure, welding time, and heartwood/sapwood showed significant effect on length and location of the crack in the welded zone. Data evaluation showed that combination of 1...

Objective To study the clinical and histopathologic features of cutaneous eyelid melanomas and identify prognostic factors in the behavior of such tumors. Design Retrospective observational case series. Participants Twenty-three patients with cutaneous eyelid melanomas without conjunctival involvement. Methods Patients’ charts were reviewed for clinical information, treatment procedure, and disease course (updated at the time of study). Histopathologic sections from all surgical procedures were reviewed. Main outcome measures Histologic type of melanoma, tumor growth phase, Clark’s level of invasion, tumor thickness, and other microscopic features were evaluated in each case. The width of excision margins was considered and measured histologically when possible. Results There was no gender predilection. The lower eyelid was more frequently involved than the upper eyelid or canthi. Seventeen cases (74%) were invasive, and six (26%) were in situ melanomas. Lentigo maligna melanoma was the most common histologic type, accounting for 61% (14 cases) of all melanomas and 53% (9 cases) of invasive melanomas. Superficial spreading melanoma accounted for 22% (5 cases) and nodular melanoma for 17% (4 cases) of all melanomas. Surgical excision, as the treatment of choice, was incomplete in nine cases, two thirds of which were lentigo maligna melanoma (in situ or invasive). Tumor reappeared in 77.8% of these cases. Fourteen patients had initial narrow excisions, and three of them (21.4%) had local recurrences. Although recurrence occurred in one each of our “in situ,” “thin,” and “thick” melanomas, it proceeded to distant metastases and death only in the “thin” one. Adjuvant radiotherapy was used in six patients with successful disease control in two cases. Conclusions Eyelid skin melanomas have a relatively good clinical prognosis. The histologic type and thickness of the primary melanoma were not clearly related to the clinical behavior once they were completely excised. The use of very narrow excisions of 5 mm or less was associated with greater frequency of local recurrence. Lentigo maligna melanomas were the largest tumors at presentation and, despite being thinner, were a greater surgical challenge. This type of melanoma is almost certainly underdiagnosed by ophthalmologists.

International audience; Linear vibration welding of good quality pine (Pinus sylvestris) wood from Sweden containing a small proportion of a native mixture of terpenoic acids, known under the collective name of rosin, has been shown to yield joints of much upgraded water resistance. This has been shown to be due to the protecting influence the molten rosin from the wood itself has on the welded interphase, because of the water repellency of rosin. Joints of unusually high percentage wood failure but modest strength were obtained, rosin apparently reinforcing the welded interphase to yield weldline strengths always much higher than the strength of the surrounding wood. (C) Koninklijke Brill NV, Leiden, 2011.

To study the clinical and histopathologic features of cutaneous eyelid melanomas and identify prognostic factors in the behavior of such tumors.Retrospective observational case series.Twenty-three patients with cutaneous eyelid melanomas without conjunctival involvement.Patients' charts were reviewed for clinical information, treatment procedure, and disease course (updated at the time of study). Histopathologic sections from all surgical procedures were reviewed.Histologic type of melanoma, tumor growth phase, Clark's level of invasion, tumor thickness, and other microscopic features were evaluated in each case. The width of excision margins was considered and measured histologically when possible.There was no gender predilection. The lower eyelid was more frequently involved than the upper eyelid or canthi. Seventeen cases (74%) were invasive, and six (26%) were in situ melanomas. Lentigo maligna melanoma was the most common histologic type, accounting for 61% (14 cases) of all melanomas and 53% (9 cases) of invasive melanomas. Superficial spreading melanoma accounted for 22% (5 cases) and nodular melanoma for 17% (4 cases) of all melanomas. Surgical excision, as the treatment of choice, was incomplete in nine cases, two thirds of which were lentigo maligna melanoma (in situ or invasive). Tumor reappeared in 77.8% of these cases. Fourteen patients had initial narrow excisions, and three of them (21.4%) had local recurrences. Although recurrence occurred in one each of our "in situ," "thin," and "thick" melanomas, it proceeded to distant metastases and death only in the "thin" one. Adjuvant radiotherapy was used in six patients with successful disease control in two cases.Eyelid skin melanomas have a relatively good clinical prognosis. The histologic type and thickness of the primary melanoma were not clearly related to the clinical behavior once they were completely excised. The use of very narrow excisions of 5 mm or less was associated with greater frequency of local recurrence. Lentigo maligna melanomas were the largest tumors at presentation and, despite being thinner, were a greater surgical challenge. This type of melanoma is almost certainly underdiagnosed by ophthalmologists.