Abstract
According to the study of mechanical properties, wood is an elastic or elastoplastic material that presents different structural behaviour when tensioned or compressed. From the viewpoint of elasticity, wood is con-sidered anisotropic, or rather it is a material with elastic properties that vary with the direction considered. During tree growth, the internal structure of the solid material consisting of the wood becomes highly orient-ed and therefore anisotropic. To study the failure modes of wooden parts and to observe their anisotropy in this process, we performed a series of exploratory tests on models of beams, taking into account the different positions of fibers and growth rings and the different relationships between height and length for a specific specie of wood, in other words, a test with tangent, radial and inclined load applied to the fibers. The pieces were made of dicotyledonous wood that was first category and free of defects, making a total of nine samples in three groups. Failure by shearing and normal stresses was observed and was well characterized in terms of records left in the samples. In addition, when describing the failure modes, the results are discussed with the presentation of images and graphics for each case. Keywords: Anisotropy, Failure modes, Beams, Wood, Experimental exploration.
Highlights
According to the study of mechanical properties, wood is an elastic or elastoplastic material that presents different structural behaviours when tensioned or compressed
To study the failure modes of wooden parts and to observe their anisotropy in the failure process, a series of exploratory tests were performed on the models of beams, taking into account the different fiber positions and growth rings and the different relationships between height and length for a specific specie of wood
It is important to mention that NBR 7190/1997 from Brazilian Association for Standardization (ABNT) was used as reference for the procedures performed. Because these were exploratory tests and scientific analysis of a preliminary investigation, which aimed to verify the influence of the wood anisotropy in modes of rupture of bending parts, there is no specific normalization for this kind of work
Summary
According to the study of mechanical properties, wood is an elastic or elastoplastic material that presents different structural behaviours when tensioned or compressed. According to KONOPKA et al 0, wood is an inhomogeneous, anisotropic, and porous material with moisture-, temperature-, and time-dependent behaviour. The internal structure of the solid material consisting of the wood becomes highly oriented and anisotropic. The three orthogonal planes RT, RL, and LT formed by these directions are three planes of symmetry of the internal structure of the wood, as represented in Figure 1(a) and (b). Depending on the relative position in which the pieces of wood are extracted from the trunk of the tree, several relationships between the growth rings and the fibers can be formed (Figure 1(c))
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