IMPACT ON COMPOSITE BOARD
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.
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.
- Eric ParoissienPhysics Engineering Expert
+33 (0)5 34 36 26 84
Eric ParoissienPhysics Engineering Expert
+33 (0)5 34 36 26 84
<p style="text-align: justify;">Eric Paroissien completed <a href="http://thesesups.ups-tlse.fr/3/">his doctoral thesis</a> at Toulouse University III on the mechanical behaviour of bolted and glued hybrid assemblies in aeronautics.</p> <p style="text-align: justify;">The objective is to model in order to understand better, and to understand in order to model better. Within this framework, a partnership with the "Institut supérieur de l’aéronautique et de l’espace" (ISAE), an aerospace engineering school in Toulouse, was launched to facilitate research on bolting and glueing with professor Frédéric Lachaud.</p> <p style="text-align: justify;">In 2007, he joined Sogeti High Tech in Toulouse, where he had the opportunity, within the framework of research, to continue his thesis work for Airbus. Since 2008, he has been in charge of an internal innovation project, dubbed JoSAT (Joint Stress Analysis Tool), which aims to improve our understanding, by means of modelling, of the mechanical behaviour of multi-material assemblies (metals, composites) and multi-technique assemblies (bolting, glueing) in order to produce an industrialisable analysis and design tool from these relationships.</p>