Mechanical behaviour of sawn timber of silver birch under compression loading

Collins, Steven G.; Fink, Gerhard

doi:10.1080/17480272.2020.1801836

Cited by 10 publications

(7 citation statements)

References 20 publications

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“…The appearance of flame wood was observed during the visual inspection. As mentioned, in this study, the position of each individual timber board within the tree stem was known [33]. Therefore, the presence of flame wood within the tree can be described.…”

Section: Flame Woodmentioning

confidence: 96%

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Grain angle determination of silver birch by laser light scattering and tensile fracturing

Collins

Fink

2022

Mater Struct

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Reliable non-destructive methods for grain angle determination are essential for the evaluation of mechanical properties of timber. In the present study, the detection of grain angle by means of laser light scattering patterns is investigated on small-scale specimens and timber boards of silver birch, along with the relationship to fracture angle and tensile strength. Results on small-scale specimens indicate applicability of laser scattering method, as the detected grain angles and the fracture angles show a strong correlation, $$r = 0.94$$ r = 0.94 . Three-dimensional grain angles, derived from surface grain angles, show a well defined relationship to strength, which can be described with wood-based failure criteria from literature. Furthermore, the paper presents new findings regarding the detection of flame wood through laser scattering. It was shown that small-scale specimens with flame wood tend to have higher grain angles, higher density, and lower strength, relative to specimens without. Nevertheless, for timber boards, the influence of flame wood on the strength was insignificant.

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Section: Flame Woodmentioning

confidence: 96%

“…From the 60 planks, 70 timber boards were obtained (one or two per plank). The location of each timber board within the stem of the tree was identified, for details see previous studies, [33,34].…”

Section: Specimensmentioning

confidence: 99%

Grain angle determination of silver birch by laser light scattering and tensile fracturing

Collins

Fink

2022

Mater Struct

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“…A hierarchical model was developed for the prediction of hardwood (birch) timber board stiffness and the reduction of stiffness due to knots. Suitable global and local predictions for silver birch timber are feasible, given the dynamic modulus of elasticity, median slope of grain, and knot geometries (Collins and Fink 2022). Similarly, a mechanical model was developed to accurately predict the strength of laminated veneer lumber (LVL) beams manufactured from veneers rotary, peeled from early to mid-rotation subtropical hardwood plantation logs, allowing to check for various construction strategies.…”

Section: Modelling Of Ewps and Design For Structuresmentioning

confidence: 99%

11th Hardwood Conference Proceedings

2024

Hardwood Conference Proceedings

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Black locust (Robinia pseudoacacia L.) is the most widespread non-native tree species in Europe and has had a significant impact on the Central European landscape and forestry. The black locust has many exceptional characteristics that represent considerable potential for use by man. The climate shift in recent decades in Central Europe could further strengthen the importance of this tree species. However, there are also risks arising from the invasiveness of the black locust. Like Hungary, Czechia has had many years of experience with this tree species. Still, the current approach between these two countries, particularly in conventional forestry, differs. This paper attempts to summarise how the management of Robinia and its stands is viewed in Czechia, where the common forestry utilization of black locust is currently not considered due to its invasiveness. The reason for a more reserved forestry attitude in Czechia can be associated with the relatively frequent stem deformities of Robinia stands, which are often attributed to frost. However, the frost deformities and low stem-form quality of some Robinia stands do not affect their vigour and potential to invade adjacent habitats. It often takes considerable effort to remove black locust, especially where the spreading of Robinia threatens valuable adjacent ecosystems. On the other hand, there is great potential for the use of Robinia in Czechia. It can be found in controlled energy crops, fast-growing plantations (lignicultures), some land reclamation projects or urban greenery. Robinia can also be grown in small stands or in groups of trees surrounded by arable land that does not allow the tree to spontaneously spread. Regarding the production plantations of Robinia, the Hungarian experience and breeding program can be very inspiring for Czechia. Generally, there is a move towards 'site-specific management', but with a strong emphasis on the precautionary principle. Finding and then consistently applying a balanced approach to black locust management that not only allows for the potential but also respects the risks of Robiniait is currently a key challenge for Czech forestry, landscape and nature conservation.

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“…The clamped area during testing was 80 x 45 mm 2 . After testing, the failure mode of the specimens is analysed and documented [8].…”

Section: Experimental Investigationsmentioning

confidence: 99%

“…Prediction of ultimate load was based on utilization ratio in the failure criteria and load F from the FE model. The utilization for point k was defined by the failure function in Equation (7), where is the averaged stress state at point k. Assuming proportional stresses, the ratio between failure stresses and applied stresses, gk, was obtained by solving Equation (8). Furthermore, assuming linear elasticity, the ratio between ultimate load and applied load is equal to minimum gk, and thus, the predicted failure load Fu can be estimated by Equation (9).…”

Section: Ultimate Load Predictionmentioning

confidence: 99%

Modelling the Effect of Three-Dimensional Grain Angle on the Tension Strength of Birch Wood

Collins

Jaaranen

Fink

2023

World Conference on Timber Engineering (WCTE 2023)

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In the present paper, the effect of three-dimensional grain direction on the tension strength of small-scale birch wood specimens is investigated. The grain angles are measured on all four surfaces of the specimens using laser light scattering technique, and afterwards, the specimens are destructively tested in tension. A numerical model is developed to predict the tensile strengths. The model is a combination of a linear elastic finite element model, with local orthotropic material orientations defined based on the measured grain orientations, and stress-based phenomenological failure criteria, with stress averaging. Strength predictions from the numerical model are compared to the experimental results, and, additionally, material strength properties are calibrated by minimizing the difference between the predictions and experimental results. A simple analytic model is further investigated and evaluated against the numerical model. Results indicate that the numerical model can predict the tensile strength of the specimens based on the measured grain angles. Stress averaging improved strength predictions by reducing localized stress peaks. Calibrated strength properties further improved the predictions and are compared with the literature. With only grain angle information, however, the numerical model does not significantly improve predictions, relative to the simple analytical model.

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Mechanical behaviour of sawn timber of silver birch under compression loading

Cited by 10 publications

References 20 publications

Grain angle determination of silver birch by laser light scattering and tensile fracturing

Grain angle determination of silver birch by laser light scattering and tensile fracturing

11th Hardwood Conference Proceedings

Modelling the Effect of Three-Dimensional Grain Angle on the Tension Strength of Birch Wood

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