Effects of macro- and micro-structural variability on the shear behavior of softwood
2004
Müller, Ulrich | Sretenovic, Aleksandra | Gindl, Wolfgang | Grabner, Michael | Wimmer, R. (Rupert) | Teischinger, Alfred
Longitudinal shear strength and shear modulus of spruce and larch wood with a maximum of micro- and macro-structural variability was determined using a new testing method. Oven-dry density and slope of grain were measured after the shear tests. For the spruce wood samples, a data set of fiber and cell wall properties, i.e., lignin content, microfibril angle, fiber length, lumen diameter, cell wall thickness, latewood proportion, and ring width, was available. A multiple linear regression analysis of all fiber and cell wall properties showed a significant, but not very strong effect on the variability of shear strength (R² = 0.21). It is thus demonstrated that micro-structural variability plays a minor role in the variability of shear properties. By contrast, a multiple linear regression involving shear modulus, density, and slope of grain as three independent variables revealed an excellent possibility to model the variability of shear strength (R² = 0.72). This study demonstrates the potential for non-destructive evaluation of the shear strength of solid wood.
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