Dynamic Strain Measurement Mechanism Analysis for Aerospace Structures with FBG Sensors

Fiber Bragg grating (FBG) strain sensors are widely used in the manufacturing and performance testing of aerospace structures. The FBG strain sensors are attached to the tested aerospace structure. The strain on the surface of the tested structure is transmitted through the adhesive layer to the fiber optic grating and measured by the FBG strain sensor. The ratio between the strain measured by FBG strain sensors and the actual strain on the surface of the tested structure is called the strain transfer rate. The strain transfer rate is mainly determined by the physical characteristics of the FBG sensor installation structure. Different from traditional static strain measurement, the transfer process of strain dynamic is more complex, which significantly affects the accuracy and reliability of dynamic strain measurement. This article analyzes the mechanism of dynamic strain measurement with FBG strain sensors attached in aerospace structures and establishes a finite element model for dynamic strain measurement structure. The dynamic strain measurement mechanism of FBG strain sensors for aerospace structures is obtained, and the main factors that affect the strain transfer rate and their variation principles have been analysis based on simulation results. The preferable installation parameters for FBG strain sensors are recommended to improve the data accuracy of FBG strain sensors, and ensure the test reliability for spacecraft structures.