Numerical modeling of a fiber optic sensor in its environment for civil engineering applications

In this paper, we developed a numerical modeling of a sensor composed of a single mode optical fiber inserted between two thin steel ribbons that are embedded in a polyurethane-type material. The different steps of calculation are performed using the method of finite element discretization. From a mechanical view point, the ribbon transfers its applied external loading to the fiber in the unidirectional form. This transmission causes birefringence in the optical fiber by modifying the opto-geometrical parameters related to the difference between principal stresses in the fiber core. The polarization phase shift enables to evaluate the applied load. The application of this study is about the development of an instrumentation dedicated to the analysis of road traffic (vehicle WIM). The numerical results presented, show the behavior of the sensor as a function of the ribbon geometry for elastic massive under load. These results should be validated from experiments taking into account environmental characteristics and conditions of use.