Investigation of crack quantification using distributed fiber optic sensors considering crack angles

Advancements in high-resolution distributed fiber optic sensing (DFOS) have demonstrated its effectiveness in quantifying crack widths. However, most existing studies assume that the crack opening direction aligns with the sensor direction. Few studies have addressed the quantification of crack width using distributed fiber optic sensors when the crack opens in other directions. This study aims to develop novel algorithms for quantifying both crack angles and widths using distributed fiber optic sensors through a combination of experimental investigations and numerical simulations. A calibration rig was designed and manufactured to replicate arbitrary-angle crack scenarios, enabling the creation of different crack angles in a two-dimensional plane. Various types of fiber optic cables were employed on the calibration rig to intersect the crack surface at different angles. Numerical simulations were conducted to interpret the strain transfer mechanisms of different fiber optic cables under arbitrary angle crack scenarios. Finally, two algorithms were developed and validated to quantify the crack width and opening direction using DFOS data. Given that the crack opening direction often differs from the fiber optic cable direction in practical applications, this study provides valuable insights for more accurate damage quantification using DFOS and enhances the understanding of optical fiber sensor behavior in real cracking scenarios.