Análise de estruturas tipo honeycomb submetidas à carga de impacto

Abstract

There is a growing interest by the industries in structural solutions that combine low mass with high impact-energy absorption. Components that have these characteristics are frequently used in aeronautical and airspace industries. The hexagonal cellular structure called honeycomb, made of metallic materials such as aluminum or nonmetallic such as Nomex®, is a solution for this demand. However, one of the challenges in using this type of structure is that its performance is heavily dependent on manufacturing parameters. Characteristics such as edge width, wall thickness, cell density (number of cells per structure area) and material properties influence the energy absorption capacity of the honeycomb. In impact situations, the most common failure mechanism is plastic deformation through progressive folding which promotes energy dissipation with more or less efficiency according to the parameters mentioned above. For this reason, the failure mode analysis of the component is important for project development. An efficient project seeks for high specific energy absorption and high crush force efficiency, the latter given by the ratio of the average crushing load to the maximum crushing load. Within this context, this study investigates the behavior of honeycomb structures with different combinations of geometric parameters and constituent materials in impact situations. In order to achieve this goal, finite element analyses are performed using the computational tool Abaqus. First, quadrilateral and hexagonal tubular cells are analyzed in order to understand the mechanisms and variables that govern this type of simulation. It is confirmed that the hexagonal cell is more suited for energy-absorption applications, surpassing the total absorbed energy of the quadrilateral cell by 47% by the end of an impact simulation. Next, hexagonal cell honeycomb numeric models are created using data provided by an experimental study found in the literature. With these models, a comparative analysis is conducted using distinct honeycomb structures made of aluminum alloys Al 3003, Al 5052 e Al 5056 and cell sizes of ⅜ in, ½ in and ¾ in. It is verified that the honeycomb parameter combination of the highest cell density (⅜ in cell) made with the highest mechanical resistance material (Al 5056) provides the highest crush force efficiency and the highest specific energy absorption and, therefore, among the tested cases, is the most appropriate for the presented application.