Sawing Processes as a Way of Determining Fracture Toughness and Shear Yield Stresses of Wood

Hlásková, Luďka; Orłowski, Kazimierz A.; Kopecký, Zdeněk; Jedinak, M.

doi:10.15376/biores.10.3.5381-5394

Cited by 21 publications

(18 citation statements)

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“…Methods of determining these properties on the basis of cutting data were minutely described in the papers by Hlaskova et al (2015), Orlowski and Atkins (2007) and Orlowski and Palubicki (2009). In this case, values of fracture toughness R ⊥ and shear yield strength τ γ⊥ for perpendicular direction of cutting speed v c to wood direction Φ G−vc = 90° (Fig.…”

Section: Methodsmentioning

confidence: 99%

Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)

et al. 2020

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In this paper, absolute and density normalized cutting model parameters of natural and impregnated Scots pine (Pinus sylvestris L.) are shown and a method for the calculation of their corresponding material properties in the principal material directions of wood is presented. The parameters were determined from measurements of cutting power on a sash gang saw, and are in detail the fracture toughness and the shear yield strength of wood. The cutting model used for fitting the data and calculating the parameters is based on a minimum energy criterion originally developed to describe an orthogonal single tooth cutting process where the chip of an isotropic material is built by shear. The effects of impregnation on wood are clearly visible in cutting power and model parameters, where for large chips less power is required compared to natural wood. Impregnated pine wood shows a reduced value of shear yield strength compared to natural pine whilst the correlated fracture toughness increased. The observed behavior might be explained by a lower moisture content of the impregnated pine compared to natural wood. Orthotropic fracture toughness and shear yield strength constants of natural and impregnated Scots pine might be used to predict cutting power for other cutting geometries and processes like circular sawing.

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Section: Methodsmentioning

confidence: 99%

Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)

et al. 2020

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“…The same results are reported by Csanády and Magoss (2013) for processing wood and wood-based materials. This conclusion was confirmed experimentally for frame saw (Orlowski 2007;Orlowski and Atkins 2007;Orlowski and Palubicki 2009) and for circular saw cutting (Kopecký et al 2014;Hlásková et al 2015). This is why it is possible to describe precisely the dependence of the cutting force on the varying uncut chip thickness, using two experimental points resulting from at least two independent measurements.…”

Section: Theoretical Backgroundmentioning

confidence: 66%

Cutting Test as Source of Fracture Toughness and Shear Yield Strength for Axial-Perpendicular Model of Wood Cutting

Hlásková

Kopecký

Solař

et al. 2019

W&FS

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The objective of this study was to develop and design a model of calculation of fracture parameters for axial-perpendicular direction of wood cutting. Two selected wood species of Central Europe provenance spruce (Picea abies L.) and beech (Fagus sylvatica L.) of two different levels of MC (w ¼ 8% and 16%) were sawn. Measurements of energetic effects (cutting power and cutting force) while sawing wood were carried out on the laboratory stand, simulating conditions of circular saw blade cutting. Using the newly designed model, it is possible to determine fracture toughness and shear yield strength only on the basis of the cutting tests. Unknown parameters, which are then applied in the model, were set based on calculation of the forces acting on the workpiece and the tool. Using the measured cutting force and the feed force, other components of the resulting active force were calculated. The computation was based on Ernst-Merchant's force decomposition diagram. Results confirmed the obvious influence of the anatomical structures and MC on the size of fracture parameters.

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“…The same results are reported by Csanády and Magoss (2013) for processing wood and wood-based materials. This conclusion was confirmed experimentally for a sash gang saw (Orlowski 2007;Orlowski and Atkins 2007;Orlowski and Palubicki 2009) and for circular saw cutting (Kopecký et al 2014, Hlásková et al 2015. Therefore, it is possible to precisely describe the dependence of the cutting force on the varying uncut chip thickness, using two experimental points resulting from at least two independent measurements.…”

Section: Fracture Mechanics-based Modelmentioning

confidence: 71%

“…Both values were suitable only for a given cutting edge direction, which is characterized by the mean value of the fibre cutting angle φ2 and cannot be considered material constants . Hlásková et al (2015) proposed a combined method for the determination of fracture toughness and strength parameters for basic cutting-edge positions for the longitudinal and perpendicular directions of cutting. However, the main drawback of this method is that two types of machine tools with different kinematics are required.…”

Section: Fracture Mechanics-based Modelmentioning

confidence: 99%

Fracture toughness and shear yield strength determination for two selected species of central European provenance

Hlásková

Orłowski

Kopecký

et al. 2018

BioRes

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When offcut of wood is formed by shearing, Atkins’s analyses of sawing processes can be applied. Using this modern approach, it is possible to determine the fracture toughness and shear yield strength of wood. This model is only applicable for the axial-perpendicular cutting direction because both of these parameters are suitable for the given direction of cutting edge movement and cannot be considered material constants. Alternatively, these parameters can be recalculated for the perpendicular and axial directions of cutting when the parameters are considered non-variable quantities. The set of data necessary for calculation can be easily obtained while cutting wood with common circular saw blades. It is necessary to ensure a minimum of two levels of workpiece height and two diverse levels of feed speed. The main aim was to develop an alternative methodology for simultaneous determination of wood fracture toughness and shear yield strength for two principal directions regarding wood grains on the basis of cutting tests performed during circular saw blade cutting for two selected wood species of Central Europe provenance, such as spruce (Picea abies (L.) Karst.) and beech (Fagus sylvatica L.).

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Sawing Processes as a Way of Determining Fracture Toughness and Shear Yield Stresses of Wood

Cited by 21 publications

References 0 publications

Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)

Cutting model parameters from frame sawing of natural and impregnated Scots pine (Pinus sylvestris L.)

Cutting Test as Source of Fracture Toughness and Shear Yield Strength for Axial-Perpendicular Model of Wood Cutting

Fracture toughness and shear yield strength determination for two selected species of central European provenance

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