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Anotace:
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In ROSS, R. -- WANG, X. Proceedings 18th International Nondestructive Testing and Evaluation of Wood Symposium. Madison, Wisconsin, USA: Forest Products Laboratory, 2013, s. 70—78. The goal of the study was to analyze and measure behavior of tree (Juglans regia L.) subjected to the mechanical load in terms of its strain response. The analysis addresses issues of urban forestry that calls for a high quality deformation data measured on trees' surfaces in a non-contact and non-invasive way. For these purposes, the 3d digital image correlation (DIC) was proposed and tested against standard extensometers. Measured tree was subjected to a bending by a pulling test to induce the strain in tree stem. DIC successfully provided field strain on a tree bark despite its highly complicated geometry. Vertical averaging of the strain field obtained by the DIC revealed that a tree stem behaves according to the beam theory showing compression and tension parts. The absolute values of strain measured by both techniques agree with each other in order of magnitude, DIC returning lower values (approximately 21.1% and 40.8% for compression and tension part respectively).
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