1639
journal of materials research and technology 2021;14:1630 e 1643
it was found that, concerning the experimental results, deflection increased from 0.85 P max onward, reaching a deflection of 5.02 mm for the maximum load, 11.3% higher than the experimental correspondent. Because the Mult_layer model is derived from the Mult_sigma19.7 model, the differ- ence between both occurred only for the most advanced stage of the non-linear curve segment. The use of the Mult_layer model for ST (Fig. 10(b)) resulted in a maximum deflection of 6.64 mm, which represents 98.7% of the maximum experimental value (6.73 mm). For all step loads, it was also found that this model was virtually identical to the Mult_sigma7.6 model (Fig. 9(b)) and well adjusted to the experimental results (Fig. 10(b)).
Table 3 e Deflections (mm) for modeling of SL and ST, single and layered model. P / P max SL ST Single- layer Three- layers Single- layer Three- layers
0.2 0.4 0.6 0.8 1.0
0.74 1.48 2.22 2.96 3.70
0.76 1.51 2.27 3.02 3.78
1.11 2.23 3.34 4.46 5.57
1.11 2.22 3.33 4.44 5.54
elasticity were E T / E L ¼ 0.571 and E TL / E LL ¼ 0.350. In this case, considering this is a composite product with different layer proportions and material characteristics than those of the present study, the results were also very satisfactory, with deflection differences resulting in 0.56 and 0.76% for the lon- gitudinal and transverse directions, respectively. The differences between the moduli of elasticity from one layer to another can be significant when the type of adhesive and their density are different. This was shown in an experi- mental study by [20], in which specimens were cut from the inside of each layer of commercial panels, produced with a thickness of 18 mm, with adhesives from the outer layers (melamine-urea-phenol-formaldehyde) and the inner layer (methylene-diphenyl-diisocyanate) and, with the density of the outer layers 40% higher than the density of the inner layer. The tests resulted in the values of the moduli of elasticity of the outer layers (5148 and 4845 MPa) and the inner layer (2314 and 1666 MPa). The importance of means to determine the properties for each layer of the OSB panel was highlighted [20], as well as the difficulties in cutting specimens from the inner of each layer, and that greater homogeneity is expected for a smaller thickness of the OSB. In these aspects, the relevance of the present study must be highlighted, providing a method to obtain the equivalent moduli of elasticity to be applied, in computational modeling design. 3.1.2. Non-linearity applied to the layered model SL and ST specimens were modeled based on the results of the layers ' elastic properties and on the implementation of the adjusted non-linear models (Fig. 8). In the first case (Fig. 10(a)),
3.2.
Normal bending stress considering single and
multi-layer models
3.2.1. SL specimen modeled - normal stress The normal stress was obtained considering the maximum load of 556.5 N applied in the SL specimen in the bending test. The
Fig. 14 e Maximum bending stress for ST specimen e single-layer [MPa]: (a) tension in direction X (b) compression in direction X (c) tension in direction Z (d) compression in direction Z.
Fig. 13 e Normal bending stress versus load e SL specimen, with single-layer and layered models.
Made with FlippingBook - Online magazine maker