Comparison and Analysis of Radial and Tangential Bending of Softwood and Hardwood at Static and Dynamic Loading

Abstract

This paper should primarily lead to a targeted expansion of the database dealing with bending characteristics, and thus help to understand the static and dynamic bending strength depending on the direction of external forces. Wood is very often used in the structural elements of buildings and wood products (e.g., furniture), in which there is both a static load, and in many cases a dynamic load, whilst the direction of loading is usually not considered. Specifically, the paper focuses on determining the bending strength and impact strength of seven economically-important wood species in the Czech Republic. The research includes not only the above-mentioned strength characteristics, but also the elastic characteristics, i.e., the static modulus of elasticity, and the dynamic modules of elasticity determined using the ultrasound and resonance methods. The procedure was methodologically in accordance with the valid harmonized standards or the usual methodological regulations. The most significant finding can be considered that the largest difference of the mean values of impact strength in the radial direction to the tangential direction was recorded for spruce wood, namely 50.3%. Slightly smaller differences were observed for larch wood, i.e., 41.2%. Minor differences of around 20% were recorded for beech, ash and oak wood. A difference with the opposite trend was recorded for birch wood rather than for the above-mentioned woods, namely −9.5%. Linden wood showed almost no difference (−0.8%). With regard to static bending strength, it was found that the largest difference (radial/tangential) was recorded for oak wood, i.e., 7.9%, while smaller differences were found for linden wood amounting to 6.6% and birch 4.7%. For spruce, larch, beech and ash wood, these differences are negligible. Another finding is that the dynamic modules of elasticity are greatly overestimated compared to static modules of elasticity. In the case of the examined wood of coniferous trees, these differences were up to a maximum of 20%. For wood of wood species with a diffuse-porous structure of wood, the differences were more pronounced, i.e., the range of 36% to 68%, and for wood species with a ring-porous structure in the range of 21% to 43%.

Effect of the Longitudinal Tensile Creep on the Stiffness of Radiata Pine (Pinus radiata D. Don)

“…However, in this research, it was found that the tangential pieces with a density of 0.39 g cm −3 resulted in higher moduli (≈11 GPa) than the radial specimens (≈9 GPa) of the same density. This mechanical response has also been found in coniferous and broadleaf species [83], in which the tangential pieces reached 17% higher than the specimens tested in the radial direction [84].…”

Evaluation of heating temperature and time on bending properties of Taurus cedar wood

“…It's known that ultrasonically determined mechanical values are generally higher than values those of statically determined. When compared to static results, an overestimation of MOE is the fact when using US, and differences were more pronounced in the wood species that has diffuse-porous structures (Borůvka et al 2020). As seen in Table 1, dynamic values were higher than static values for all treatment groups.…”

Surface Characteristics of One-Sided Charred Beech Wood

“…For instance, the values of dynamic and static bending strength of wood are different depending on the direction of the external force applied (in the radial or tangential loading direction). The difference of mean values in impact bending strength in the radial direction towards tangential was observed to be about 20% for beech [ 59 ]. Thermal conductivity of beech is about 18% higher in the radial than the tangential direction.…”