ABSTRACT
The panels have been increasingly used in civil and rural buildings, among others, especially those plywood panels by good mechanical performance. In many applications, panels may be subject to cyclic loading, and thus, the knowledge of the effect of fatigue is of fundamental importance. However, the standards ABNT NBR ISO 2426 [1212 Associação Brasileira de Normas Técnicas (ABNT). NBR ISO 2426: “Madeira compensada - Classificação pela aparência superficial”. Rio de Janeiro, 2006.], NBR ISO 1096 [1313 Associação Brasileira de Normas Técnicas (ABNT). NBR ISO 1096: “Madeira compensada - Classificação”. Rio de Janeiro, 2006.], NBR 9489 [1414 Associação Brasileira de Normas Técnicas (ABNT). NBR 9489: “Condicionamento de corpos de prova de compensados para ensaios - Requisitos”. Rio de Janeiro, 2011.] and NBR 9533 [1515 Associação Brasileira de Normas Técnicas (ABNT). NBR 9533: “Compensado - Determinação da resistência à flexão estática”. Rio de Janeiro, 2012.] which have the classifications and test methods for panels, do not consider the effect of fatigue in material properties, which motivates the development of researches in this area. The objective of this work was to evaluate the effect of the number cyclic fatigue load (NC) (0 - reference, 3600, 7200, 22500, 45000, 67500, 90000) for the oscillation frequency equal to 1.0 Hz in the bending modulus of elasticity (MOE) of commercial eucalyptus plywood panels. Six specimens were fabricated for each number of cycles, resulting in 36 samples. The results evidenced significant reductions of the MOE from 22500 cycles, implying that 0, 3600 and 7200 cycles provided statistically equivalent results. The logarithmic regression model was the most representative (R² = 64.28%), presenting as an alternative in the prediction of the MOE decay for fatigue cycles higher than those evaluated in this study.
Keywords
Fatigue; Plywood panel; Analysis of variance; Regression models
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