PSI - Issue 70

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

475

time intervals. During lifting phase due to the additional forces including water resistance and weight redistribution a continuous increase in strain values were recorded at both the sensors which contributes to pipe deformation. While analyzing the recorded strain values it is observed that the values are higher during lifting phase than dipping phase indicates that the increased mechanical stress on the pipe when it is retrieved from the water. The result shows that the maximum strain experienced by the pipe exceeds the initial predictions. The Strain Calculation without Temperature Compensation equation is used for calculating the strain values since the pipe strain is not affected by temperature variations in the underwater environment. Since the temperature fluctuations did not influence the strain measurements which allows for precise assessment of the mechanical response of the pipe.

Fig.5. Strain Response of HDPE Pipe during Underwater Testing

6. Conclusion

The experimental data confirms that the HDPE pipe experiences significant strain variations when subjected to external loading and environmental influences. The FBG strain sensors effectively captured real-time strain fluctuations, demonstrating their reliability for structural health monitoring in marine applications. Higher peak strain values were observed under specific loading conditions, highlighting the need for careful handling to minimize material stress. The analysis suggests the importance of alternative support mechanisms to mitigate strain effects in HDPE pipe and enhance long-term performance. Future studies could explore varying load conditions and