SUrvivability of STructures for Aircraft INjured by Directed energy shocks 21 – SUSTAINED21

Current civilian and military aircrafts and flying systems (e.g. UAVs) are designed from thin, lightweight, multi-material structures assembled by bolting, gluing or built-on fabrication. Due to their constitution, these structures are vulnerable to explosion phenomena that occur on their surface during a natural aggression such as lightning, or intentional aggression such as Directed Energy Weapons (DEA) or lasers. These aggressions are governed by multiphysical mechanisms in the environment close to the impacted surface (thermal, mechanical, electrical, EM). They generate superficial (top plies cracks, skeins of stripped fibres) or core damage (spalling, perforation). The residual performances of the structures are significantly diminished and the internal equipment (tanks, embedded systems) are exposed.
It is necessary to protect these systems to limit their vulnerability. The objectives of the project SUSTAINED21 are in line with the civilian and military needs whose systems are susceptible to these different types of aggression, in order to envisage industrial solutions with high added value that will increase their survivability. The challenges arising from these applications are to have available a method for dimensioning the protection of structures that breaks with the current industrial practices, and contribute to the operational superiority of forces.
The first objective of this study is to build an experimental database and a mapping of the damage induced by three different means of energy deposition: the lightning mean (which constitutes the reference test), the pulsed laser and the electron gun. The use of this damage mapping will make it possible to assess the similarities between the damage produced by the two alternative means with respect to the "lightning" reference test, the results of which are already available on CFRP composites. It will also ensure that they are representative, particularly with respect to the electromagnetic environment. By extension, this database can be used to compare damage from impacts at very high speeds.
The second objective consists in numerically simulating the behaviour of the materials of interest under attack in order to evaluate the capability to predict the damage caused and to identify the limits of current models, particularly with regard to the application of a multiphysical loading. The achievement of this objective will be based on the adaptation of existing models and on the comparison with the mapping of the database.
The third objective is to establish a methodology for using the technological bricks developed in objectives 1 and 2. The influence of the protective layers will be explored here in order to help, in the long term, the emergence of a tool for dimensioning protections. This predictive approach will be transposable to the military field for the dimensioning of future directed-energy weapons according to the layers of protection to be penetrated.
This approach will satisfy the challenges for industry to reduce the costs of development studies, the most robust protections being the only ones subjected to certification/qualification lighting tests, the lightning generator being used as the final reference mean.
The project is based on a partnership between an academic project leader who has worked on the modelling of damage caused by lightning, an academic partner specialized in the implementation of an experimental laser shock device, and an industrial partner expert in specifying protection layers. The proposed work involves a subcontractor in the SME sector with know-how in the implementation and analysis of laser shocks, and will be supported by DGA-Ta as the expert in lightning tests certification. The work is part of the continuity of collaborations and scientific partnerships with the DGA-Ta in Toulouse and Airbus Operation. Being interested in this field, DGA Missiles Testing SG will be able to offer its support.