Mechanical behavior of walnut (<i>Juglans regia</i> L.) and cherry (<i>Prunus avium</i> L.) wood in tension and compression in all anatomical directions. Revisiting the tensile/compressive stiffness ratios of wood

Bachtiar, Erik Valentine; Rüggeberg, Markus; Niemz, Peter

doi:10.1515/hf-2017-0053

Cited by 9 publications

(7 citation statements)

References 24 publications

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“…The strain release energy for each mode was estimated via the virtual crack closure technique (VCCT) and the finite element method (FEM), in which a certain modulus of elasticity (MOE) and shear modulus was used. Bachtiar et al (2017) determined the MOE data of the walnut and cherry specimens; the wood for the present study was from the same region (Table 2). The strain energy release rate for VCCT was calculated (Krueger 2004).…”

Section: Methodsmentioning

confidence: 99%

Determination of mode I and mode II fracture toughness of walnut and cherry in TR and RT crack propagation system by the Arcan test

2017

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Two specimen types, each from walnut and cherry wood, were prepared for tangential-radial (TR) and radial-tangential (RT) crack propagation systems at 65% of RH and 20°C before mode I and mode II fracture toughness was determined through Arcan tests. It was found that fracture toughness in mode I is in agreement with literature data. In the mode II test, however, the crack propagated in the direction normal to the shear plane and not parallel to it. The release rate of strain energy in terms of the opening failure in mode II was lower than that in mode I. It can be concluded that it is difficult to determine the fracture toughness of RT or TR propagation in hardwood specimens in mode II.

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Section: Methodsmentioning

confidence: 99%

Determination of mode I and mode II fracture toughness of walnut and cherry in TR and RT crack propagation system by the Arcan test

2017

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“…V. Sebera et al: Wood-adhesive bond loaded in mode II wood lamellas is very difficult due to variability of wood properties, their geometry and possible different elastic moduli in tension and compression as found for various species, for instance for beech at MC below 13% (Ozyhar et al 2013) or for cherry and walnut (Bachtiar et al 2017). In addition to the unknown position of the NA, these uncertainties contribute to the fact that it is very difficult to obtain true fracture toughness in mode II for wood-bonded specimens.…”

Section: Dic Analysismentioning

confidence: 99%

Wood-adhesive bond loaded in mode II: experimental and numerical analysis using elasto-plastic and fracture mechanics models

et al. 2020

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The goal of the study was to analyze fracture properties of adhesive bond using a three-point end-notched flexure test and the compliance-based beam method. Critical strain energy release rates (GIIc) and cohesive laws were obtained for adhesive bonds made of European beech (Fagus sylvatica L.) and adhesives such as EPI, MUF, PRF and PUR. The experiments were assisted with FE analyses employing three different material models of wood: elastic (Elas), symmetric elasto-plastic (EP) and elasto-plastic with different compressive and tensile yield stresses parallel to fiber (EP+). The highest mean GIIc was achieved for PUR (5.40 Nmm−1) and then decreased as follows: 2.33, 1.80, 1.59 Nmm−1 for MUF, EPI, and PRF, respectively. The failure of bondline was brittle and occurred at bondline for EPI, MUF and PRF, and ductile and commonly occurring in wood for PUR adhesive. The FE simulations employing cohesive models agreed well with the experimental findings for all adhesives. FE model with Elas material was found accurate enough for EPI, MUF and PRF adhesives. For PUR adhesive, the model EP+ was found to be the most accurate in prediction of maximal force. The impact of friction between lamellas may be up to 4.2% when varying friction coefficient from 0 to 1. The impact of the grain angle distortion (α) with respect to longitudinal specimen axis showed its high influence on resulting stiffness and maximal force. It was found that three-point end-notched test is suitable for EPI, MUF, and PRF, while it is less appropriate for a bond with PUR adhesive due to notable plastic behavior.

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“…On the other hand, the input parameter to estimate the shear strengths (s u ) are the in-axis strengths (r uL , r uR , r uT ). All input parameters for walnut wood (Juglans regia L.) based on [13,14] are presented in Table S1.…”

Section: Numerical Approachesmentioning

confidence: 99%

“…This assumption, on the other hand, is not true since the strength in R direction is often higher than in T direction [8]. In fact, for walnut wood r uR are in average 20% higher than r uT [14].…”

Section: Theoretical Approaches For Estimating the Shear Strengthmentioning

confidence: 99%

“…The new approaches are based on the combination of both empirical and analytical in-and off-axis material properties, which enable them to be used to estimate both shear modulus and shear strength. The approaches are implemented for walnut wood (Juglans regia L.), for which a sufficient data set is available [13,14]. Furthermore, statistical analyses are performed to compare and validate the results with the shear properties that are experimentally obtained using the above-mentioned Arcan and shear block test setups.…”

Section: Introductionmentioning

confidence: 99%

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Estimating shear properties of walnut wood: a combined experimental and theoretical approach

et al. 2017

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In this study, several theoretical models to numerically estimate shear properties of orthotropic materials are introduced. These approaches are based on the combination of Hankinson's empirically derived formula with other empirical and analytical calculations. Next to shear moduli, which are estimated from the elastic moduli and Poisson's ratios, shear strengths are also estimated from the in-axis strengths. The models are validated by mechanical tests on walnut wood (Juglans regia L.), for which a sufficient data set can be found in literature. The Arcan test is used to estimate the shear moduli, while the shear block test is used to estimate the shear strengths. The results show that the model, which is based on a combined use of Hankinson's formula and tensor rotation, gives the best estimation of shear moduli as evaluated by the minimum differences to the experimentally obtained results. For the shear strengths, a combination of Hankinson's formula and Norris' failure criterion shows the best agreement in comparison to the experimental data. The theoretical calculations may be used for a time efficient estimation of shear modulus and strength in comparison to the very time-consuming experimental estimation.

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Mechanical behavior of walnut (Juglans regia L.) and cherry (Prunus avium L.) wood in tension and compression in all anatomical directions. Revisiting the tensile/compressive stiffness ratios of wood

Cited by 9 publications

References 24 publications

Determination of mode I and mode II fracture toughness of walnut and cherry in TR and RT crack propagation system by the Arcan test

Determination of mode I and mode II fracture toughness of walnut and cherry in TR and RT crack propagation system by the Arcan test

Wood-adhesive bond loaded in mode II: experimental and numerical analysis using elasto-plastic and fracture mechanics models

Estimating shear properties of walnut wood: a combined experimental and theoretical approach

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