Equivalent crack based mode II fracture characterization of wood

In the present work fracture (Mode I) was induced through three point-bending tests in two wood species used in timber construction: Maritime pine ( Pinus pinaster Ait.) and Norway spruce ( Picea abies L.). Load–displacement curves were experimentally determined and corresponding Resistance -curves ( R -curves) obtained using an equivalent linear elastic approach. An inverse method is presented to identify cohesive crack properties of a cohesive crack bilinear model used to simulate fracture in both wood species, combining experimental data and a developed genetic algorithm. Good agreement between numerical and experimental load–displacement and R -curves was obtained. Conclusions are drawn from finite element simulations regarding the extent of the numerical cohesive zone computed for each studied wood.

Comparison of fracture properties of two wood species through cohesive crack simulations

Stereovision measurements on evaluating the modulus of elasticity of wood by compression tests parallel to the grain

If there is one domain of civil engineering in which adhesives are currently booming, then it is timber engineering. Natural adhesives have been used for centuries to structurally connect timber elements, a trend that culminated in the beginning of the 20th century with the introduction of glue-laminated beams. With the introduction of synthetic adhesives, and their increasing economic success after World War II, a wide range of products is now available that have the potential to free timber engineering from most of its structural and size limitations. This review article is intended to shed some light on the current state-of-the-art regarding adhesively bonded connections in the context of timber engineering. First, the relevant properties of timber as an adherend are discussed, then different – including several hybrid – approaches for structurally jointing timber are illustrated and finally, different design approaches are presented.

Adhesively bonded connections in the context of timber engineering – A Review

Shear deformation and fracture of human cortical bone.

In this work, the applicability of the Iosipescu and off-axis test methods for the shear characterization of clear wood was investigated. Wood of maritime pine (Pinus Pinaster Ait.) was used. Iosipescu shear tests were carried out for oriented specimens in the three natural symmetry planes of wood (LR, LT and RT planes), whereas off-axis tests were performed only in the LR and LT planes. Finite element analyses were conducted in order to access the stress and strain fields in the test section of the specimens. It was found that the Iosipescu and off-axis tests provide different shear moduli values. It was also shown that the Iosipescu test gives lower and upper bounds of shear strengths, whereas the off-axis test gives only a lower bound, directly from the measured loads.

N.M. Garrido

Papers

A comparison between the iosipescu and off-axis shear test methods for the characterization of Pinus Pinaster Ait