Flange joint monitoring based on strain measurement with fiber optic sensors embedded in gaskets

The paper demonstrates the effectiveness of using numerical simulation to select parameters of the system for monitoring the deformation behavior of structures. Consideration is given to a bolted flange connection with a gasket, the performance of which is determined by the level of bolt tightening. Bolt tension control technique is based on the strain measurement with fiber optic sensors embedded in the gasket. The results of numerical modeling of deformation for different variants of bolt tensioning are discussed. Strain measurement in the gasket by means of distributed fiber-optic sensors on the basis of Rayleigh scattering is carried out taking into account the results of numerical simulation. Another type of fiber optic sensors that is based on the Bragg gratings is used to implement additional control of the results of measurement. An algorithm to realize strain measurement by two types of sensors located on the same optic fiber is proposed. The results of experimental strain measurements demonstrate that fiber optic sensors can be used to detect changes in bolt tensioning, which can cause failure of a flange joint.