Materials and Structures Used in Aeronautics: Present and Future Perspectives

In recent years, significant advancements have been made in the development of novel materials for aeronautic applications. This effort aims to reduce costs by extending the operational life of structural and engine components, improving fuel economy, load capacity, and flight range. This paper investigates metallic materials such as aluminum alloys, titanium alloys, magnesium alloys, steels, nickel superalloys, and metal matrix composites (MMCs), providing an overview of recent advancements and highlighting current challenges and future perspectives in aeronautic metals. Several crucial factors are considered when selecting materials for aviation applications. These materials must withstand various environmental conditions, including humidity and temperature, as well as mechanical stresses such as tension, compression, bending, cyclic loads, creep, and torsion. The selection process is complicated by the wide range of available materials and the numerous variables involved, with cost being a critical factor in making an informed decision. In aviation, the most significant material characteristics are strength combined with lightness and stability in the operating environment. Trial and error can be costly in this context, necessitating well-planned design and engineering to ensure resistance to aerodynamic forces during flight. This approach has drawn the interest of aircraft designers since the inception of the Boeing 747, which utilized 1.3% composite materials. Modern aircraft, such as the Airbus A380 and Boeing 787, now incorporate 25% and 50% composite structures, respectively. Research has increasingly focused on enhancing the efficiency of structural engineering and material development through the use of sandwich structures. These structures are valued for their excellent stiffness-to-weight ratios and impact energy absorption properties. A typical sandwich structure consists of two thin, rigid face layers bonded to a core material. While various core materials like balsa and foam have been used in aviation, the honeycomb structure is the most prevalent. Honeycomb core configurations, including hexagon, reinforced hexagon, rectangle, flex-core, and square cell, primarily serve to support normal loads in the longitudinal direction and shear loads along the transverse axis.