Strain Field Reconstruction of High-Speed Train Crossbeam Based on FBG Sensing Network and Load-Strain Linear Superposition Algorithm

Strain monitoring of high-speed train crossbeams is essential because as a vital load-bearing structure carrying several tonnes of under-vehicle equipment for high-speed trains, they are likely to be damaged under prolonged loading. This paper proposed a strain field reconstruction and monitoring method based on load-strain linear superposition. Firstly, finite element analysis was performed with two loads and three loads showing that the algorithm reconstructed the strain field of the crossbeam on a high-speed train with an average relative error of less than 0.01%. Then a sensing network with 24 fiber Bragg grating sensors was established. Train line operation tests were conducted and strain measurement information was obtained. On this basis, the strain field of the crossbeam was reconstructed with an average fitting error of less than 2%. This research shows the power of the load-strain linear superposition method in the strain field monitoring of the load-bearing structure for the operation and maintenance of the train.