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

Abstract

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.

Comparison of methods for determining shear modulus of wood

“…For a better understanding, their shear moduli assignment will be transposed to the definition of the present study. The results of Bachtiar et al (2017) show constantly 5-12% higher shear moduli in LR and TL direction than in RL and LT direction, respectively. Only for RT and TR directions, there is no clear trend.…”

“…For beech, the density differs not as much within an annual ring, which corresponds to a lower influence of the grip end effect between RL and LR direction. Bachtiar et al (2017) examined the shear moduli by Arcan tests on all six shear planes of walnut wood (LR, RL, LT, TL, RT and TR) at different moisture contents. The indexing of the shear moduli does not correspond to the indexing in the present study, so that G LR , for example, corresponds to G RL assignment of Bachtiar et al (2017).…”

“…Bachtiar et al (2017) examined the shear moduli by Arcan tests on all six shear planes of walnut wood (LR, RL, LT, TL, RT and TR) at different moisture contents. The indexing of the shear moduli does not correspond to the indexing in the present study, so that G LR , for example, corresponds to G RL assignment of Bachtiar et al (2017). For a better understanding, their shear moduli assignment will be transposed to the definition of the present study.…”

Wood Derived Cellulose Scaffolds—Processing and Mechanics

“…In view of these boundary conditions, Iosipescu and Arcan tests represent the most suitable tests for deriving shear moduli. [ 55,56 ] The determination of shear strength parallel to fiber direction is straightforward as the failure is recognizable as shear failure. Determining shear strength perpendicular to fiber orientation is more difficult as the wood merely fails in compression rather than in shear.…”

“…Determining shear strength perpendicular to fiber orientation is more difficult as the wood merely fails in compression rather than in shear. [ 56 ]…”