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journal of materials research and technology 2021;14:1630 e 1643
Fig. 15 e Layered ST 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.
stress along the panel ' s thickness (Fig. 12(b-c)) allows the optimization of the panels regarding their layer composition, e.g., by changing the layer thickness. Considering the values of the normal bending stress to the step loads (Fig. 13) allows visualizing the effects of non- linearity for both models (single-layer and multi-layer). Di- rection X shows a reduction in the growth rate of such stress given the increase in applied load. Comparatively, for the single-layer model to the layered model and the maximum load, in directions X and Z, the maximum stress differences were 5.4 and 25.2%, respectively. Of these values, the case of direction X is more critical for meeting the types of panels standardized, for example by EN 300 [47]. 3.2.2. ST specimen modeled e normal stress In the bending tests with the dimension Ls in the transverse direction (ST specimen), the maximum load value was 205.3 N, for which the maximum stress estimated was 12.7 MPa. With the Mult_sigma5 model (Fig. 6(b)), for direction X which is aligned to Ls , the maximum tension and compression stress obtained (Fig. 14(a-b)) was 10.6 MPa (bot- tom and top faces). Regarding this value, the result estimated with the supposedly elastic-linear case was 19.8% higher,
results were obtained with the Mult_sigma15 (Fig. 6(a)) and Mult_layer model (Fig. 8(a)). In direction X, aligned with dimen- sion Ls , when modeling with Mult_sigma15, the maximum bending stress values for the maximum load were 27.3 MPa (tension on bottom face), and compression was 27.3 MPa (top face), as shown in Fig. 11(a-b). The value calculated based on the elasticity theory equation (material with elastic-linear behavior) was 32.9 MPa, thus being 20.5% higher than that obtained by the non-linear computational model adjusted for vertical displace- ments. In direction Z (Fig. 11(c-d)), which represents the width of thespecimen, the maximum values of tension and compression were 4.1 MPa (bottom and top faces). Although these values are lower than in the other direction, this was expected due to the geometric characteristics and static scheme of the specimen (as a wide-beam). During the bending test, the rupture was well characterized in the central region of the specimen, where the highest values of the normal bending stress were obtained. For the Mult_layer model (Fig. 12), both in the X and Z di- rections, the maximum stress occurs on the outer faces of the specimens because of their association with the material with the greatest modulus of elasticity. Unlike the specimen modeled as a single-layer (with the rigidity of the bending test), in the case with discretized layers, the distribution of
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