Abstract
Direct measurement of strain field in a mechanically loaded Norway spruce branch–stem junction was performed by means of electronic speckle pattern analysis. Results were compared with strain distribution in a polyester cast of identical shape as the branch–stem junction, and a simplified polyester model consisting of two half-cylinders. Compared to polyester models, the branch–stem junction was characterised by a very homogeneous distribution of strain, which can be interpreted as a homogeneous distribution of stress in terms of fraction of material strength. This optimised transfer of mechanical load from the branch to the stem is achieved by a combination of naturally optimised shape with, additionally, optimised mechanical wood properties in the junction area.
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Müller, U., Gindl, W. & Jeronimidis, G. Biomechanics of a branch – stem junction in softwood. Trees 20, 643–648 (2006). https://doi.org/10.1007/s00468-006-0079-x
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DOI: https://doi.org/10.1007/s00468-006-0079-x