PSI - Issue 70

T. Ramya et al. / Procedia Structural Integrity 70 (2025) 469–476

474

Fig.4. Experimental setup to measure strain & temperature using FBG Sensors

4.3 Data Acquisition and Analysis

As shown in figure 4. the HDPE pipe with two FBG sensors fixed on it was tested at ATF which was 7-meter deep. The experimental results were collected using a data interrogator equipped with data acquisition (DAQ) software. Each sensor was configured initially using the following equation:

Strain Calculation without Temperature Compensation

= λ−λ 0 k.λ 0 10 6

(5)

where

• ε: Strain (μm/m) • λ: Measured wavelength of the strain sensor (nm) • λ₀: Reference wavelength of the strain sensor (nm) • k: Calibration factor

5. Results and discussion

The HDPE Pipe strain analysis during underwater testing at different phase is shown in figure 5.The pipe was tested under different conditions and analyzed using Fiber Bragg Grating (FBG) sensors. When the pipe was submerged underwater with 1 ton clump weight attached at one end of the pipe the strain measurements from both the sensors exhibited an initial increase due to the applied load. Due to the combined effects of hydrostatic pressure, buoyancy forces and applied load it is observed that the strain values of pipe at fixed points were increased gradually at specific