Fibre optic sensors for the validation of the numerical simulation on the breadboard of the LARES separation system

Fibre optic sensor technology is relatively new and in the last ten years its use is becoming common in many fields of engineering. The properties of optical fibre sensors make them very promising for use on space structures. They are immune from electromagnetic interferences, resistant to chemical corrosion, compatible with the space environmental conditions. Fibre Bragg Gratings (FBG) are particularly interesting because they can be multiplexed along the same fibre. Those sensors are basically optical strain gages with many advantages over the conventional ones. In the paper it is proposed the use of those sensors for correlating experimental finite element analysis on the contact point of the separation system with LARES satellite. LARES satellite is spherical and no protruding parts are allowed on its surface. This requirement calls for a special separation system that has four contact points on the satellite surface. To counteract forces acting on the satellite during the launch phase, for the purpose of preventing accidental detachment of the separation system components from the satellite surface, a significant preload force is applied to the satellite through those four contact points. Concern about the admissibility of the consequent contact pressures arose. A direct measurement of the pressures on those contact points seems unfeasible and the purpose of the paper is to investigate the possibility of deriving the local value of the pressure by measuring with FBG sensors the strain on an accessible nearby area.