Screening the composites

Numerous technologies have been developed in order to enhance the security, performance and costs of the latest generation of airplanes. In the area of structure, a new family of composite materials has been developed, called CFRP (Carbon-Fibre Reinforced Composites). The impact study on these composite structures poses another major challenge for the scientific community. The doctoral thesis conducted in the Sogeti High Tech R&D division and the Clement Ader Institute mechanics laboratory at the University of Toulouse allows our company to play a leading role in composite materials.

Observe in order to anticipate better

Compared to conventional metals, using composite structures significantly reduces mass and costs. However, this material is subject to damage from low-force impacts. So, for instance, dropping a tool during production may result in a significant loss of strength, and thus also in premature failure. It is therefore important to understand and anticipate these reactions.

This research work examines the impact damage tolerance of composite laminates (carbon/epoxy) with ply drop-offs, in order to study their effects on the phenomenon of damage. The interest of this with respect to ply stops lies in their intrinsic vulnerability to the slightest damage. Moreover, they offer the best means for reducing weight on large parts, and are therefore indispensable in aircraft design.

Ply drop-offs

We often see ply drop-offs in large composite structures in order to optimise their use of material. In aircraft fuselages, the panels are thinner at the back of the mesh compared to areas close to stiffeners. Given the local variation in drape forming, the presence of these ply drop-offs results in both geometric and mechanical discontinuities. However, the effect of an impact, even one of low force, significantly reduces the remaining service life of composite laminates.

Studies have examined the damage mechanism of impacts on composite laminates. They measured the residual strength of the impact samples. Finally, they propose a digital simulation model that correlates well with experimental results.

todo todo
  • Eric Paroissien
    Eric Paroissien
    Physics Engineering Expert
    +33 (0)5 34 36 26 84