Determinação da rigidez da madeira com o emprego de imagens digitais
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Data
2011-07-05
Autores
Duarte, Ana Paula Coelho
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Editor
Universidade Federal do Espírito Santo
Resumo
Wood samples were submitted to standard bending and compression tests to determine their stiffness. To compare values, modulus of elasticity was first measured using a dial gage (in bending) or strain-gage (in compression). The samples were filmed at the same time and the film, captured by a Leica V-lux-20, yielded still images in the .jpg format, that were later analysed using a MatLab program. In the case of bending, three values of MOE were obtained from each image and compared to the first. One of the new methods, that permitted to calculate the deflection at the center of the sample in the image, gave values that were very close to those given by the dial. Data were also collected from the images that allowed the calculation by regression analysis of the elastic curve of the beam. MOE values so obtained were also very similar to those of the dial, with a few exceptions. The angle that subtended the curvature of the deflected beam was also found from the images, but gave MOE values quite different, in most cases. It is presumed, in this case, that the sample (a 2 by 2 by 24 cm parallelepiped) was probably too small to allow calculating with precision the lines by regression. In compression, the technique used here, the filming of two parallel lines that should become closer as the sample was loaded, did not also give good estimates of MOE. The calculated strain should amount here to only about 2 or 3 pixels, too few to guarantee a precise capture by the camera. The techniques used in this work are simple, the necessary equipment, cheap, and only one person is needed. A better camera will certainly be sufficient to make them practical and precise
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Mechanical properties , Wood , Stiffness , Módulo de elasticidade , Modulus of elasticity , Madeira , Digital images , Propriedades mecânicas , Mechanical properties , Imagens digitais
Citação
DUARTE, Ana Paula Coelho. Determinação da rigidez da madeira com o emprego de imagens digitais. 2011. 59 f. Dissertação (Mestrado em Ciências Florestais) – Programa de Pós-Graduação em Ciências Florestais, Universidade Federal do Espírito Santo, Jerônimo Monteiro, 2011.