Determination of mechanical characteristics of transversely isotropic fiber coil according to isotropic properties of its components

A fiber optic gyroscope is a complex system, which consists of the sensor and electronics unit. The sensing element includes the frameless fiber coil and integrated optical phase modulator. The article discussed the structure of frameless fiber coil. During the exploitation, the gyroscope is exposed to external factors, which influence should be minimized. It is indicated that the mechanical resonance is one of the causes of gyro-out errors in the operating mode. It is proposed to predict the behavior of the sensitive element at the design process of fiber optic gyroscopes. The authors it indicate the problem of great computing resources due the complex internal structure of the fiber coil. It is proposed to make a transition from a multi-component structure of the fiber coil to the transversely isotropic homogeneous material. Рассмотрена модель элементарного объема как ячейки периодической структуры волоконного контура. The authors considered the elementary volume model as the cell with periodic structure of fiber coil. Four tasks of finding the stress-strain state of an elementary volume of the fiber coil were set. The problem was solved by using the finite element method implemented in the software package Creo Simulate 2.0. It defined four independent mechanical characteristics of the transtropic body in the operational temperature range of the fiber-optic gyroscope. The experiment of finding natural frequencies of fiber coil in "free" suspension was carried out. Using finite element method the authors found the natural frequencies and mode shapes of the fiber coil with the transversely isotropic material model. The cylindrical coordinate system was used to set the material properties. Comparing the modal analysis results and experimental data proves that it is possible to use the obtained elastic constants to solve the deformable body mechanics problems.