On the fracture toughness of Douglas fir wood

Moisture-dependent elastic and strength anisotropy of European beech wood in tension

“…Further, the ability to withstand failure from fracture when loaded in tension perpendicular to the grain is a crucial topic in wood engineering. Although fracture toughness for wood has been investigated by several authors [14][15][16][17], data covering moisture-dependent tensile fracture toughness are limited to a few references [18][19][20][21][22].…”

Analysis of fracture toughness of structural timber

“…As in the available literature sources the n-coefficient value for Douglas fir equal to n = 2.80 is found and pine wood properties are close to those of Douglas fir, hence for further calculations n = 2.80 was assumed for the pine wood [9]. On the basis of the relation (11) were determined critical values of the energy release coefficient G 1c of the natural and modified wood specimens for the directions RL and TL.…”

“…by means of the relation: C = K ⋅ a n (9) where: n -a coefficient experimentally determined on the basis of the diagram ln(C) versus ln(a) K -numerical value determined from the point of intersection of the diagram with the ordinate axis.…”

New splitting method for wood fracture characterization

“…Additional evaluations of the load-displacement curves with FE methods are discussed on page 46. b) Linear elastic fracture mechanics (LEFM) principles Though wood is a highly anisotropic, heterogeneous and porous material, concepts of linear elastic fracture mechanics are widely accepted (Porter 1964, Schniewind and Pozniak 1971, Valentin, Adjanohoun 1992. If a specimen is cut sufficiently far from the centre of the tree, it may be considered as an orthotropic material.…”

“…It has been tried to apply linear fracture mechanics concepts on wood through non-linear elastic and anisotropic features are present. Based on early works of Schniewind (1962) and Porter (1964) on the critical energy release rate for unstable crack propagation, and on the work of Shi et al (1965) who derived crack-tip stress fields and stress intensity factors assuming rectilinear anisotropic bodies, many research work has been performed on influences of orientation, specimen shape, specimen size but also on other than geometrical parameters on fracturing of wood (Schniewind and Centeno 1973, Barrett 1976, Schniewind and Pozniak 1971, Barrett and Foschi 1977 Ewing and Williams 1979, Ebewele et al 198o, Schniewind et al 1982, Petterson and Bodig 1983, Boatright and Garrett 1983, Triboulet et al 1984, Cramer and McDonald 1989, Valentin and Adjanohoun 1992, Murphy 1979, BostrSm 1992.…”