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journal of materials research and technology 2021;14:1630 e 1643
Fig. 12 e Layered SL and detailing of the normal stress distributions in two elements positioned in the center of the specimen [MPa]: (a) stress in direction X (b) stress on three layers in direction X (c) stress on three layers in direction Z.
differences were only 2.2%. For the transverse direction, the model with a single-layer resulted in higher deflections (0.5%) than the situation with layers discretized. The differences of 2.2 and 0.5% in the SL and ST cases are insignificant, which allows validating the proposal for esti- mating the layers elastic properties, based on the results of bending tests, obtained from the ratio of the moduli of elas- ticity ( E T / E L ¼ 0.264and E TL / E LL ¼ 0.198). The method was also applied to the data published by [6] for OSB panels made of Eucalyptus grandis wood with Phenol-Formaldehyde resin in the proportion of 20:60:20, for which the ratio of the moduli of Table 2 e Mechanical and geometric parameters of the specimens. Parameters SL ST I E (Nmm 2 ) 34,193,390.0 8,291,020.8 h (mm) 10.8 10.4 b (mm) 47.9 49.4 e (mm) 3.2 3.1 i (mm) 4.3 4.2 I e (mm 4 ) 2353.3 2167.2 I i (mm 4 ) 321.8 296.4 I (mm 4 ) 5028.4 4630.7 ce (mm) 3.8 3.6 Where I E is the flexural rigidity, h the full panel thickness, b the width, e the thickness of the outer layers, i the core layer thickness; I e the inertia moment of each outer layer; I i ¼ inertia moment of the core layer, I the inertia moment of full cross-section, ce the position of the center of gravity of the outer layer concerning the neutral axis of the panel (on half-thickness).
The comparison of the results of computational modeling with the experimental ones allows inferring the most appro- priate multi-linear models for representing the OSB panels’ vertical displacements. Based on these considerations, the multi-linear model was adopted in this research. 3.1.1. Validation of the model with equivalent moduli of elasticity of strands layers For SL and ST specimens manufactured with a layer propor- tion of 30:40:30, represented generically in Fig. 7 and with the static bending test data shown in Table 2, the resolution of the linear equation system (Eq. (1)) resulted in values of the equivalent moduli of elasticity of 7167.7 MPa ( E LL ) and 1422.7 MPa ( E TL ). To validate these results, the specimens were modeled in two cases: with a single-layer (with the modulus of elasticity obtained directly from the bending test) and with three layers (with the corresponding equivalent moduli of elasticity). In the case of the SL modeled with a single-layer, the following properties were considered: E L ¼ 6812.26 MPa and n L ¼ 0.31. In the case of the ST model with a single-layer: E T ¼ 1796.75 MPa and n T ¼ 0.13 were considered. For the layered modeling, in the case of the SL specimen (Fig. 7(a)), in the outer layers the Material 1 ( E LL ¼ 7167.7 MPa and n L ¼ 0.31) was applied, and in the core layer the Material 2 ( E TL ¼ 1422.7 MPa and n T ¼ 0.13) was used. For the layered case (Fig. 7(b)), the outer and core layers were assigned Material 2 and Material 1, respectively. Based on the results obtained in the linear analysis and compared to the single-layer model (Table 3), it is possible to note that the layered model for the longitudinal direction resulted in higher deflections for each step load; however, the
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