Metamodel-based static and dynamic optimization of composite structures with ply drop-offs

Abstract

Nowadays, there is no analytical equation able to analyze the issues related to the performance of structures with ply drop-offs. In order to address this issue, a metamodel using Design of Experiments and the SunFlower Algorithm for static and dynamic optimization of composite structures with ply drop-offs was developed in this study. Through numerical simulations and experimental tests, a characterization of the static and dynamic behavior of tapered hybrid and non-hybrid tubes was proposed. Then, a metamodel was developed considering the results obtained through numerical simulations, where the best ply drop-off location that provides the best static and dynamic conditions was identified, and, posteriorly, it was applied in the manufacture of the tubes. The numerical results revealed that the hybrid tube reinforced with carbon and glass of fibers supported a high loading in buckling conditions when compared with non-hybrid tubes. Before the manufacture of the tubular structures, an experimental comparative study using honeycomb sandwich structures with different face sheets and cores was proposed to analyze the fabric characteristics. The results showed that the hybrid fabric reinforced with glass and aramid of fibers was demonstrated to be not viable for tubular structure manufacture. Then, in the manufacture of the tubular structures, the carbon, glass, and carbon/aramid hybrid fabrics were applied. The experimental results obtained with the optimized structures revealed that the hybridization provided an increase in the level of damping. The modal analyses performed on the intact and damaged structures demonstrated a smooth reduction in the first natural frequency and in the damping factor for the damaged structures. Aiming a comparative analysis between tapered and non-tapered structures, tubular structures without ply drop-offs were manufactured and experimental tests were performed. The hybrid tapered structure manufactured with carbon, aramid, and glass of fibers proved to be a promising option in compression conditions, supporting a loading of 9.489 kN, while the non-tapered structure supported a loading of 13.283 kN. In addition, this hybrid structure revealed a lower manufacturing cost when compared with the other hybrid structures, and it was considered lighter with a mass of 53 grams. The non-tapered hybrid structure had a mass of 77 grams, 30% higher than the tapered structure’s mass. Therefore, metamodel-based static and dynamic optimization was demonstrated to be feasible and advantageous for determining the optimum ply drop-off location.