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journal of materials research and technology 2021;14:1630 e 1643
For the transverse direction, with the bi-linear model, the initial yield strength estimated for a load of 123.18 N (0.6 P max ), bending moment of 6775.9 N mm and W ¼ 890.52mm 3 was 7.61 MPa, and the value of 8 MPa was adopted for the sigma8 model (Fig. 6(b)). For this value, the behavior was more rigid than the experimental one, while for yield strength of 4 MPa, the bi-linear model was more adjusted to represent the maximum experimental displacement. For the multi-linear model, the ultimate stress corresponding to the maximum load of 205 N ( P max ) was estimated, resulting in 12.6 MPa, and the value of 10 MPa was adopted for the model. In this way, for the Mult_sigma5 model the corresponding points (0; 0), (0.0028; 5), (0.0053; 8), (0.0100; 10) were defined (Fig. 6(b)). As for the model in the longitudinal direction, the model with multi- linear adjustment was tested to obtain a better approximation of the experimental deflection (6.725 mm, Fig. 5(b)), resulting in a deformation of 2.3%, which was adopted for the Mult_- sigma7.6 model (Fig. 6(b)).
2.5.
Equivalent moduli of elasticity of the OSB layers
The bending test according to ASTM D1037 [21] is easy to perform. It is used to obtain the elastic properties ( I E ) for the longitudinal and transverse directions of the OSB panels. However, these properties refer to the full thickness and not to each layer of the OSB panel. Nonetheless, computational modeling allows considering each layer of a composite, with its intrinsic properties. In this sense, based on the values E L and E T for bending the specimens extracted in the longitudinal and transverse di- rections, we sought to estimate the equivalent modulus of elasticity for each layer using a system of linear equations. For this purpose, the SL and ST specimens (Fig. 7) must be extracted from panels produced with identical materials, resin content, and moisture content. To set up the system of linear equations, the dimensions of the cross-section and the flexural rigidity of each specimen were considered, and the equivalent moduli of elasticity were represented by E LL and E TL (Fig. 7), resulting in the system of equations (Eq. (1)).
Fig. 6 e Stress x strain models: (a) SL specimen; (b) ST specimen.
30). The stress value corresponding to the plastic regime of 30 MPa was estimated with the relationship [bending moment/elastic section modulus]. In this case, for the maximum load of 556.5 N, the stress value was 32.9 MPa. Thus, for the point of a fully plastic regime, a deformation of 1% and stress of 30 MPa were adopted. The adjustment with the best approximation for an experimental deflection of 4.505 mm (Fig. 5(a)) was also tested, resulting in the Mult_- sigma19.7 model (Fig. 6(a)), in which the elastic e plastic line was extended to deformation of 1.7%.
Fig. 7 e Scheme of layers and parameters of the OSB panel to estimate the equivalent modulus of elasticity for each layer: (a) specimen cut with the long dimension aligned in the longitudinal direction; (b) specimen with the long dimension aligned in the transverse direction.
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