Open Access Open Access  Restricted Access Subscription or Fee Access

Fatigue Damage Detection of Rib-to-Deck Welded Joints Using 5cm High-Spatial-Resolution DDP-BOTDA System

J. XU, Y. DONG, H. LI, S. LI, T. JIANG, M. XIA

Abstract


In this paper, a distributed fiber optic sensor (DFOS) based fatigue crack detection system for rib-to-deck welded joints was developed by using the RP1000 distributed optical fiber sensing system. RP1000 is the latest high performance fiber optic distributed strain and temperature monitoring system recently researched and developed by Harbin Institute of Technology. The RP1000 system, which is based on differential double-pulse Brillouin optical time-domain analysis (DDP-BOTDA), can realize a spatial resolution of 5 cm and a sensing range of 5 km. The rib-to-deck welded joints specimen was a full-scale orthotropic deck specimen with weld meltthrough (WMT) of 12-mm-thick deck plate and 8-mm-thick rib. A piece of polarization-maintaining (PM) optical fiber was bonded along the weld on both deck plate and rib to form the distributed sensing network. A fatigue test was conducted and the specimen was subjected to cyclic tensile loading. The fatigue cracks were visually inspected at the root of the specimen. The strain responses of the sensing fiber near the creaks confirmed the effectiveness of damage detection and characterization of the proposed system. The RP1000 DDP-BOTDA distributed optical fiber sensing system shown good accuracy and stability with a high spatial resolution of 5 cm during the monitoring process.

doi: 10.12783/SHM2015/382


Full Text:

PDF