<p>The influence of the stacking sequence on the mechanical behavior of composite laminates is unquestionable, being one of the most important definitions for structural design. Recently, a novel stacking sequence was proposed in the literature, named Double-Double (DD), demonstrating a great homogenization capability and suitability for optimization procedures due to its double-helix characteristic. However, most DD studies are dedicated to unidirectional carbon fiber reinforced polymers (CFRP). The goal of the present investigation is to extend the DD application to woven glass fiber reinforced polymers (GFRP) for the first time. The stiffness equivalence between DD and quadriaxial (QUAD) is derived based on the classical laminate theory, indicating that it is possible to obtain DD and QUAD woven laminates with the same in-plane stiffness. Tensile tests are carried out to demonstrate experimentally the equivalence between DD and QUAD not only considering the stiffness, but also the laminate strengths. An analytical modeling is implemented to evaluate the laminate failure by applying the Hashin criterion, which is compared with the experimental results and achieved reliable estimations. The influence of multiaxial stress states is also discussed in this study, and the results show that the difference between DD and QUAD strengths is not greater than 10%. At last, a parametric analysis of the strengths of DD laminates is performed. The results highlight that, despite it is theoretically possible to define an equivalent QUAD for the DD with the highest strength, it is not applicable in practice because it would require a large number of plies.</p>

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Extending the Double-Double Concept for Woven GFRP Laminates

  • Lucas L. Vignoli,
  • Heraldo S. C. Mattos,
  • João M. L. Reis

摘要

The influence of the stacking sequence on the mechanical behavior of composite laminates is unquestionable, being one of the most important definitions for structural design. Recently, a novel stacking sequence was proposed in the literature, named Double-Double (DD), demonstrating a great homogenization capability and suitability for optimization procedures due to its double-helix characteristic. However, most DD studies are dedicated to unidirectional carbon fiber reinforced polymers (CFRP). The goal of the present investigation is to extend the DD application to woven glass fiber reinforced polymers (GFRP) for the first time. The stiffness equivalence between DD and quadriaxial (QUAD) is derived based on the classical laminate theory, indicating that it is possible to obtain DD and QUAD woven laminates with the same in-plane stiffness. Tensile tests are carried out to demonstrate experimentally the equivalence between DD and QUAD not only considering the stiffness, but also the laminate strengths. An analytical modeling is implemented to evaluate the laminate failure by applying the Hashin criterion, which is compared with the experimental results and achieved reliable estimations. The influence of multiaxial stress states is also discussed in this study, and the results show that the difference between DD and QUAD strengths is not greater than 10%. At last, a parametric analysis of the strengths of DD laminates is performed. The results highlight that, despite it is theoretically possible to define an equivalent QUAD for the DD with the highest strength, it is not applicable in practice because it would require a large number of plies.