Composite materials

Good morning EUROAVIAns,
in today Fact Friday we talk about composite materials.

Have you ever wondered why they are of particular interest in many structural applications? That’s because composites are materials usually constituted by two heterogeneous materials (or substances), meaning that even after their mixing, the original substances can be physically distinguished. This way, their mechanical performance can be guided and optimized according to the design requirements!

Common compositions are constituted by extremely stiff fibers made of glass or carbon, engulfed in a low-density resin, called the matrix. The resulting component can therefore be as strong or as light as needed by the design process, by simply tuning the ratio of both elements. Indeed, by increasing the number of fibers along a particular direction, the material’s strength to deformations along the same axis can be greatly improved.

The polymerization between high performing matrices and fibers involves high pressures and temperatures that are achieved by using autoclaves. Unfortunately, the bigger the final component to obtain, the greater the required energy and space for this process This bonding process can require even hours for a correct hardening and curing of the resins. In the end, the incredible efficiency of composites is given by the fact that their mechanical properties are orthotropic, and therefore different according to the applied load’s direction.

Differently from isotropic materials like metals, their behaviour changes greatly, but can be controlled with more accuracy. Composite materials therefore become valid alternatives to metal alloys, especially in aerospace applications where weight constraints are crucial and the resistance can be optimized according to the specific needs.