Distributed stress measurement for water pressure test of diversion steel branch pipe
The diversion steel branch pipe is large and complex to weld,requiring endurance for long-term water pressure of 6 MPa.There is a need for a high-precision,high-resolution stress measurement tech-nique for comprehensive assessment during water pressure tests.Traditional strain gauges are limited to lo-calized measurements and restricted by waterproofing,application processes,and temperature changes.This study proposes using optical frequency domain reflectometry for stress measurement in the pipe.A standard single-mode fiber sensor is laid along the weld seam for a spatial resolution of 5.8 cm.Stress corre-lates linearly with water pressure and varies periodically from 0.2 to 0.6 m along the weld seam.Maximum stress reaches 196.2 MPa at the crescent rib weld seam's waist,about 300 MPa at the main conical ring seam,and distributes symmetrically along the intersecting line,with a peak of 352.0 MPa near the waist-line and minimal stress at the top and bottom.
distributed stress measurementoptical frequency domain reflectometerdiversion steel branch pipepumped storage
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